Patent Publication Number: US-2015084340-A1

Title: Load apparatus and method of using same

Description:
RELATED AND CO-PENDING APPLICATION 
     This application is a continuation-in-part of and claims priority to co-pending U.S. patent application Ser. No. 13/682,313 entitled LOAD APPARATUS AND METHOD OF USING SAME filed Nov. 20, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The field of the invention relates generally to power systems and, more particularly, to a load apparatus that may be used in power systems. 
     At least some known systems, such as power systems, use at least one machine that is coupled to a load. The machine may be a turbine engine that generates torque and also accumulates kinetic mechanical rotational energy in the inertia of a rotating mass. The load may be an electrical system, such as an electrical generator or inverter, which converts the mechanical energy to electrical energy for a power output. The load may also be coupled to an energy storage device such that some of the power output may be stored for later use. For example, at least some known power systems provide bi-directional electrical energy or power flow, wherein the power output from the load may be transferred to the turbine engine to power up the turbine engine or the power output may be delivered to, for example, the energy storage device for storage. 
     Some power systems that provide bi-directional power flow may use high speed generators to facilitate an increased power density. At least some known high speed generators are mechanically coupled to the turbine engine. More specifically, a rotating element, such as a drive shaft, of the turbine engine may be directly coupled with a rotor shaft of the generator. The drive shaft rotates to enable the turbine engine to generate mechanical rotational energy. As the drive shaft rotates, the generator rotor shaft rotates and the generator is able to convert the mechanical energy to electrical energy. Instead of a direct mechanical connection, there may be intervening elements such as clutches, gear trains, etc. 
     Because there is no rotor-dynamic isolation between the high speed generator and the turbine engine when there is a mechanical coupling (possibly a direct connection), the inertial state of the drive shaft of the turbine engine may impact that of the rotor shaft of the high speed generator, or vice versa. For example, the high rotational speeds that are implemented may apply centrifugal forces on the drive shaft and/or the rotor shaft that may cause misalignment of the rotor shaft and/or the generator with respect to the drive shaft and/or the turbine engine. Vibrations and imbalances that might be produced by on or the other of the shafts are coupled to both shafts. Such misalignment or the like may lead to a failure of at least one component of the power system, prevent proper bi-directional power flow, and/or adversely affect the overall operation of the power system. 
     BRIEF DESCRIPTION 
     In one embodiment, a load apparatus is provided. The load apparatus may generally comprise a rotating electric machine or similar load that is configured to convert mechanical rotational energy to electrical energy for a power output. A rotor assembly is coupled to the load, wherein the rotor assembly includes a rotor shaft. The rotor shaft includes at least one end portion that includes at least one extension portion that extends radially from a surface of the rotor shaft end portion. A coupling shaft is configured to couple to the rotor shaft, wherein the coupling shaft includes a cylindrical main body portion. The coupling shaft also includes at least one end portion that extends from the main body portion, wherein the coupling shaft end portion is configured to couple to the rotor shaft end portion so as to rotationally fix the coupling shaft to the rotor shaft. The coupling shaft end portion can include an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and through the exterior surface, wherein the slot is configured to receive the extension portion therein such that the extension portion extends radially outwardly from the exterior surface. 
     In another embodiment, a power system is provided. The power system includes a machine that has a rotational drive shaft and a load apparatus that is coupled to the machine. The load apparatus includes a load that is configured to convert mechanical rotational energy to electrical energy for a power output. A rotor assembly is coupled to the load, wherein the rotor assembly includes a rotor shaft. The rotor shaft includes at least one end portion that includes at least one extension portion that extends radially from an axis of the rotor shaft end portion. A coupling shaft is configured to couple to the rotor shaft, wherein the coupling shaft includes a cylindrical main body portion. The coupling shaft also includes at least one end portion that, extends from the main body portion, wherein the coupling shaft end portion is configured to couple to the rotor shaft end portion so as to rotationally fix the two shafts together. The coupling shaft end portion includes an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and through the exterior surface, wherein the slot is configured to receive the extension portion of the rotor shaft therein such that the extension portion of the rotor shaft and the surface(s) defining the slot in the coupling shaft bear against one another at least over some span that is radially spaced from the rotational axes of the shafts, which are coaxially aligned, thereby rotationally fixing the shafts together. Although just described as an extension of the rotor shaft received in a slot in the coupling shaft, it should be appreciated that the gender relationship can be reversed and this disclosure encompasses both gender relationships. 
     In yet another embodiment, a method of using a load apparatus is provided. The method includes providing a load that is configured to convert mechanical rotational energy to electrical energy for a power output. A rotor assembly is coupled to the load, wherein the rotor assembly includes a rotor shaft including at least one end portion. The rotor shaft end portion includes at least one extension portion that extends radially outwardly from a surface of the rotor shaft end portion. A coupling shaft is provided, and the coupling shaft is configured to couple to the rotor shaft, wherein the coupling shaft includes a cylindrical main body portion and at least one end portion that extends from the main body portion. The coupling shaft end portion includes an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and through the exterior surface. The coupling shaft end portion is coupled to the rotor shaft end portion such that the slot receives the extension portion therein such that the extension portion extends radially outwardly from the exterior surface. 
     In another embodiment, a load apparatus is provided and includes a load that is configured to convert mechanical rotational energy to electrical energy for a power output. A rotor assembly is coupled to the load, wherein the rotor assembly includes a rotor shaft that has at least one end portion. The rotor shaft end portion includes at least one extension portion that extends radially outwardly from a surface of the rotor shaft end portion. A coupling shaft is configured to couple to the rotor shaft, wherein the coupling shaft includes a cylindrical main body portion and at least one end portion that extends from the main body portion. The coupling shaft end portion is configured to couple to the rotor shaft end portion. The coupling shaft end portion includes an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and to the exterior surface. The slot is configured to receive the extension portion therein such that the extension portion cannot extend through the exterior surface. 
     In yet another embodiment, a load apparatus generally comprises a first shaft having at least one end portion that includes at least one extension portion that extends radially outwardly from a surface of the end portion. A second shaft is configured to couple to the first shaft, wherein the second shaft includes a cylindrical portion that has at least one end portion. The second shaft end portion is configured to couple to the first shaft end portion, and the second shaft end portion includes an exterior surface, an opposing interior surface, and at least one slot that extends from the interior surface and through the exterior surface, wherein the slot is configured to receive the extension portion therein such that the extension portion extends radially outwardly from the exterior surface. 
     In another embodiment, a load apparatus generally includes a first shaft having at least one end portion, wherein the first shaft end portion includes at least one extension portion that extends radially outwardly from a surface of the first shaft end portion. A second shaft is configured to couple to the first shaft, wherein the second shaft includes a cylindrical portion that includes at least one end portion, wherein the second shaft end portion is configured to couple to the first shaft end portion. The second shaft end portion includes an exterior surface and an opposing interior surface. At least one slot extends from the interior surface and to the exterior surface, wherein the slot is configured to receive the extension portion therein such that the extension portion cannot extend through the exterior surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of an exemplary power system; 
         FIG. 2  is a partially exploded perspective view of an exemplary load apparatus that may be used with the power system shown in  FIG. 1  and taken from area  2 ; 
         FIG. 3  is a cross-sectional view of a portion of the load apparatus shown in  FIG. 2  and taken along line  3 - 3 ; 
         FIG. 4  is a perspective view of a portion of the load apparatus shown in  FIG. 2  and taken from area  4 ; 
         FIG. 5  is a block diagram of a portion of the load apparatus shown in  FIG. 2  and taken from area  5 ; 
         FIG. 6A  is a perspective view of a portion of an alternative load apparatus that may be used with the power system shown in  FIG. 1  and taken from area  6  (shown in  FIG. 2 ); and 
         FIG. 6B  is a perspective view of a portion of another alternative load apparatus that may be used with the power system shown in  FIG. 1  and taken from area  6  (shown in  FIG. 2 ). 
     
    
    
     DETAILED DESCRIPTION 
     The systems, apparatus, and methods described herein provide embodiments of a load apparatus that may be used in a power system, wherein the load apparatus is able to facilitate bi-directional power flow within the power system and the load apparatus is coupled to a machine such that the load apparatus is rotordynamically isolated from the machine. In some embodiments, the load apparatus includes a load and a rotor assembly that is coupled to the load, wherein the rotor assembly includes a rotor shaft that is configured to rotate within at least a portion of the load. The load apparatus also includes the use of a coupling shaft, such as a quill shaft, that is configured to couple the rotor shaft to a drive shaft of the machine such that the rotor shaft is axially and/or radially isolated from the drive shaft to facilitate rotordynamic isolation between the load apparatus and the machine. Moreover, as described herein, the machining of various components of the load apparatus is cost effective. 
       FIG. 1  illustrates one embodiment of a power system  100 . It should be noted that the present disclosure is not limited to power systems, and one of ordinary skill in the art will appreciate that the current disclosure may be used in connection with any type of system. In some embodiments, power system  100  includes a machine, such as a gas turbine engine  102 . The present disclosure is not limited to any one particular type of machine, and one of ordinary skill in the art will appreciate that the current disclosure may be used in connection with other types of machines. For example, machine may be a compressor, a pump, a turbocharger, and/or various types of turbines. 
     Moreover, in some embodiments, turbine engine  102  includes an intake section  112 , a compressor section  114  coupled downstream from the intake section  112 , a combustor section  116  coupled downstream from the compressor section  114 , a turbine section  118  coupled downstream from the combustor section  116 , and an exhaust section  120 . It should be noted that, as used herein, the term “couple” is not limited to a direct mechanical, thermal, communication, and/or an electrical connection between components, but may also include an indirect mechanical, thermal, communication and/or electrical connection between multiple components. 
     Turbine section  118 , in the some embodiments, is coupled to compressor section  114  via a drive shaft  122 . Combustor section  116  includes a plurality of combustors  124  and is coupled to compressor section  114  such that each combustor  124  is positioned in flow communication with compressor section  114 . Turbine section  118  is coupled to compressor section  114  and to a load apparatus  128  via the drive shaft  122 . In some embodiments, load apparatus  128  includes a load (not shown in  FIG. 1 ) that is an electrical system, such as a high speed electrical generator or inverter. Load apparatus  128  is coupled to an energy storage device  130 , such as a battery. In some embodiments, compressor section  114  and turbine section  118  includes at least one rotor disk assembly (not shown) that is coupled to drive shaft  122 . 
     During operation, intake section  112  channels air towards compressor section  114  wherein the air is compressed to a higher pressure and temperature prior to being discharged towards combustor section  116 . The compressed air is mixed with fuel and other fluids and ignited to generate combustion gases that are channeled towards turbine section  118 . More specifically, fuel, such as natural gas and/or fuel oil, air, diluents, and/or Nitrogen gas (N 2 ), is injected into combustors  124 , and into the air flow. The blended mixtures are ignited to generate high temperature combustion gases that expand as they are channeled towards turbine section  118 . Turbine section  118  converts the thermal energy from the gas stream to mechanical rotational energy, as the combustion gases impart rotational energy to turbine section  118  and to the rotor disk assembly. 
     The mechanical rotational energy is converted to electrical energy via load apparatus  128  for a power output. As explained in more detail below, load apparatus  128  facilitates bi-directional power flow within power system  100  such that the power output from load apparatus  128  may be transferred to turbine engine  102  to power the turbine engine  102  or the power output may be delivered to, for example, energy storage device  130 . 
     In some embodiments, the mechanical rotational energy that is generated by turbine section  118  is enabled by the rotation of drive shaft  122 . As drive shaft  122  rotates, at least a portion of load apparatus  128  rotates. For example, a rotor shaft (not shown in  FIG. 1 ) of load apparatus  128  rotates. Due to the high rotational speeds implemented by drive shaft  122  and/or the rotor shaft, mechanical stress may be endured by each. The mechanical stress may cause misalignment of the rotor shaft and/or load apparatus  128  with respect to drive shaft  122  and/or turbine engine  102 . However, as described in more detail below, load apparatus  128  is rotordynamically isolated from turbine engine  102 . Accordingly, mechanical stress and/or misalignment of the rotor shaft and/or load apparatus  128  with respect to drive shaft  122  and/or turbine engine  102  may be inhibited. 
       FIG. 2  is a partially exploded perspective view of load apparatus  128  taken from area  2  (shown in  FIG. 1 ).  FIG. 3  is a cross-sectional view of a portion of load apparatus  128  taken along line  3 - 3  (shown in  FIG. 2 ).  FIG. 4  is a perspective view of a portion of load apparatus  128  taken from area  4  (shown in  FIG. 2 ). Referring to  FIGS. 2 and 3 , load apparatus  128  includes a load  200  that is a high speed generator configured to convert mechanical rotational energy to electrical energy for a power output. Alternatively, load  200  may be any suitable type of device or system that is configured to generate electrical energy that enables load apparatus  128  and/or power system  100  (shown in  FIG. 1 ) to function as described herein. 
     Referring to  FIGS. 3 and 4 , a rotor assembly  204  is coupled to load  200  such that at least a portion of load  200  substantially circumscribes at least a portion of rotor assembly  204 . In some embodiments, rotor assembly  204  is the rotor assembly described in co-pending U.S. patent application Ser. No. 13/682,378 entitled ROTOR ASSEMBLY AND METHOD OF USING SAME filed Nov. 20, 2012, which is incorporated herein by reference in its entirety. Rotor assembly  204  includes a substantially cylindrical rotor shaft  206  that is coupled to a sleeve apparatus  208  such that at least a portion of rotor shaft  206  is positioned within sleeve apparatus  208  ( FIG. 4 ). In some embodiments, rotor shaft  206  includes a first end portion  214 , a middle portion  216 , and a second end portion  218 . Rotor shaft  206  is positioned within sleeve apparatus  208  such that at least a portion of middle portion  216  is positioned within sleeve apparatus  208 , and first end portion  214  and second end portion  218  are not positioned within sleeve apparatus  208 . As such, rotor shaft  206  is configured to rotate within at least a portion of load  200 . 
     In some embodiments, second end portion  218  of rotor shaft  206  has a diameter that is substantially equal to the diameter of middle portion  216 . Referring to  FIGS. 2 and 4 , first end portion  214  is configured to be removably coupled to a coupling shaft, such as a quill shaft  220 . More specifically, in some embodiments, first end portion  214  includes a first surface  230  that is substantially arcuate and a second surface  232  that is substantially planar such that the first end portion is positionable within an opening (not shown) on a first end portion  240  of quill shaft  120 . For example, the opening on first end portion  240  of quill shaft  120  is configured to receive first end portion  214  of rotor shaft  206 . Moreover, first end portion  240  of quill shaft  120  includes a splined engagement member  241  to facilitate the coupling between first end portion  240  of quill shaft  120  and first end portion  214  of rotor shaft  206 . 
     Quill shaft  220 , in some embodiments, is configured to couple rotor shaft  206  to drive shaft  122  (shown in  FIG. 1 ). For example, while first end portion  240  of quill shaft  220  is configured to couple to a first end portion  214  of rotor shaft  217 , a second end portion  242  of quill shaft  220  is configured to couple to an end portion (not shown) of drive shaft  122 . In some embodiments, second end portion  242  of quill shaft  220  includes a substantially cylindrical interior portion  244  and a substantially cylindrical exterior portion  246  that substantially circumscribes at least a portion of interior portion  244 . An opening  250  is defined within interior portion  244  such that an end portion of drive shaft  122  is positionable within opening  250 . Accordingly, rotor shaft  206  is coupled to drive shaft  122  via quill shaft  220  such that rotor shaft  206  is axially and/or radially isolated from drive shaft  122  to facilitate rotordynamic isolation between load apparatus  128  and turbine engine  102  (shown in  FIG. 1 ). In some embodiments, quill shaft  220  is configured to facilitate axial freedom of movement that enables drive shaft  122  to float axially and independently of the axial movement of rotor shaft  206 . 
     Referring to  FIGS. 2 and 3 , load apparatus  128  includes a housing apparatus  260  that is coupled to load  200  and to rotor assembly  204  such that housing apparatus  260  substantially encloses at least a portion of load  200  and at least a portion of rotor assembly  204  therein. In some embodiments, housing apparatus  260  is the housing apparatus described in U.S. Pat. No. 8,796,875 entitled HOUSING APPARATUS AND METHOD OF USING SAME issued on Aug. 5, 2014, which is incorporated herein by reference in its entirety. 
     Referring to  FIG. 2 , in some embodiments, load apparatus  128  also includes a control system  280  that is coupled to load  200 , wherein control system  280  is configured to control the power output produced by load  128 . For example, control system  280  is configured to control channeling torque produced by load  200  in a first direction  282  towards turbine engine  102  such that the power output may be used by turbine engine  102  or in a second direction  284  toward energy storage device  130  such that the power output may be stored for later use by the power system  100 . 
     During operation, referring to  FIGS. 2 ,  3 , and  4 , turbine section  118  (shown in  FIG. 1 ) converts the thermal energy from the gas stream to mechanical rotational energy, as the combustion gases impart rotational energy to turbine section  118  and to a rotor disk assembly (not shown). The mechanical rotational energy is then converted to electrical energy via load  200 . In some embodiments, the mechanical rotational energy that is generated by turbine section  118  is enabled by the rotation of drive shaft  122 . As drive shaft  122  rotates, rotor assembly  204  rotates. For example, rotor shaft  206  of rotor assembly  204  rotates. Due to the high rotational speeds implemented by drive shaft  122  and/or rotor shaft  206 , drive shaft  122  and/or rotor shaft  206  may undergo mechanical stress that results in a misalignment of rotor shaft  206 , rotor assembly  204 , and/or load  200  with respect to drive shaft  122  and/or turbine engine  102 . 
     However, because rotor shaft  206  is coupled to drive shaft  122  via quill shaft  220 , rotor shaft  206  is axially and/or radially isolated from drive shaft  122 . As such, there is rotordynamic isolation between load apparatus  128  and turbine engine  102 . As a result, impact to rotor shaft  206  from rotational deviations that drive shaft  122  may endure is inhibited. Similarly, impact on drive shaft  122  from rotational deviations that rotor shaft  206  may endure is inhibited. Accordingly, mechanical stress, wear and/or misalignment of rotor shaft  206  and/or load apparatus  128  with respect to drive shaft  122  and/or turbine engine  102  may be prevented. 
     Moreover, load apparatus  128  is configured to thermally isolate turbine engine  102  from load apparatus  128 . As such, heat that is dissipating from turbine engine  102  does not substantially impact load apparatus  128 . Accordingly, the potentially negative performance effects of the thermally limited components of turbine engine  102  and/or load apparatus  128  are substantially reduced. Load apparatus  128  is also configured to substantially reduce the available heat transfer area to propagate heat conductivity to turbine engine  102 , and provide flexibility with cooling options that can be applied to, for example, attachment components. 
       FIG. 5  is a block diagram of control system  280  taken from area  5  (shown in  FIG. 2 ). In some embodiments, control system  280  includes a controller  320  that is operatively coupled to load  200  (shown in  FIG. 3 ). For example, controller  320  may be coupled to at least one control valve or switch (not shown). In some embodiments, controller  320  is configured to control the valve or switch to control the power output being channeled in either first direction  282  (shown in  FIG. 2 ) or second direction  284  (shown in  FIG. 2 ). Controller  320  is also configured to change the power output flow from first direction  282  to second direction  284  and/or from second direction  284  to first direction  282 . Controller  320  is enabled to facilitate operative features of the valve or switch, via features that include, without limitation, receiving permissive inputs, transmitting permissive outputs, and transmitting opening and closing commands. 
     In some embodiments, controller  320  may be a real-time controller and may include any suitable processor-based or microprocessor-based system, such as a computer system, that includes microcontrollers, reduced instruction set circuits (RISC), application-specific integrated circuits (ASICs), logic circuits, and/or any other circuit or processor that is capable of executing the functions described herein. In one embodiment, controller  320  may be a microprocessor that includes read-only memory (ROM) and/or random access memory (RAM), such as, for example, a 32 bit microcomputer with 2 Mbit ROM and 64 Kbit RAM. As used herein, the term “real-time” refers to outcomes occurring in a substantially short period of time after a change in the inputs affect the outcome, with the time period being a design parameter that may be selected based on the importance of the outcome and/or the capability of the system processing the inputs to generate the outcome. 
     In some embodiments, controller  320  includes a memory device  330  that stores executable instructions and/or one or more operating parameters representing and/or indicating an operating condition of load apparatus  128  and/or power system  100  (shown in  FIG. 1 ). In some embodiments, controller  320  also includes a processor  332  that is coupled to memory device  330  via a system bus  334 . In one embodiment, processor  332  may include a processing unit, such as, without limitation, an integrated circuit (IC), an application specific integrated circuit (ASIC), a microcomputer, a programmable logic controller (PLC), and/or any other programmable circuit. Alternatively, processor  332  may include multiple processing units (e.g., in a multi-core configuration). The above examples are exemplary only, and thus are not intended to limit in any way the definition and/or meaning of the term “processor.” 
     Moreover, in some embodiments, controller  320  includes a control interface  336  that is coupled to the valve or switch and that is configured to control an operation of the valve or switch. For example, processor  332  may be programmed to generate one or more control parameters that are transmitted to control interface  336 . Control interface  336  may then transmit a control parameter to modulate, open, or close the valve or switch. 
     Various connections are available between control interface  336  and the valve or switch. Such connections may include, without limitation, an electrical conductor, a low-level serial data connection, such as Recommended Standard (RS)  232  or RS-485, a high-level serial data connection, such as USB, a field bus, a PROFIBUS®, or Institute of Electrical and Electronics Engineers (IEEE) 1394 (a/k/a FIREWIRE), a parallel data connection, such as IEEE 1284 or IEEE 488, a short-range wireless communication channel such as BLUETOOTH, and/or a private (e.g., inaccessible outside power system  100 ) network connection, whether wired or wireless. IEEE is a registered trademark of the Institute of Electrical and Electronics Engineers, Inc., of New York, N.Y. BLUETOOTH is a registered trademark of Bluetooth SIG, Inc. of Kirkland, Wash. PROFIBUS is a registered trademark of Profibus Trade Organization of Scottsdale, Ariz. 
     In some embodiments, control system  280  includes at least one sensor  335  that is coupled to load  200  and to controller  320 . In some embodiments, controller  320  includes a sensor interface  340  that is coupled to sensor  335 . In some embodiments, sensor  335  is positioned in close proximity to, and coupled to at least a portion of load  200 . Alternatively, sensor  335  may be coupled to various other components within power system  100 . In some embodiments, sensor  335  is configured to detect the level of the power output being produced by load  200 . Alternatively, sensor  335  may detect various other operating parameters that enable load apparatus  128  and/or power system  100  to function as described herein. 
     Sensor  335  transmits a signal corresponding to a power output detected for load  200  to controller  320 . Sensor  335  may transmit a signal continuously, periodically, or only once, for example. Other signal timings may also be contemplated. Furthermore, sensor  335  may transmit a signal either in an analog form or in a digital form. Various connections are available between sensor interface  340  and sensor  335 . Such connections may include, without limitation, an electrical conductor, a low-level serial data connection, such as RS 232 or RS-485, a high-level serial data connection, such as USB or IEEE® 1394, a parallel data connection, such as IEEE® 1284 or IEEE® 488, a short-range wireless communication channel such as BLUETOOTH®, and/or a private (e.g., inaccessible outside power system  100 ) network connection, whether wired or wireless. 
     Control system  280  may also include a user computing device  350  that is coupled to controller  320  via a network  349 . User computing device  350  includes a communication interface  351  that is coupled to a communication interface  353  contained within controller  320 . User computing device  350  includes a processor  352  for executing instructions. In some embodiments, executable instructions are stored in a memory device  354 . Processor  352  may include one or more processing units (e.g., in a multi-core configuration). Memory device  354  is any device allowing information, such as executable instructions and/or other data, to be stored and retrieved. 
     User computing device  350  also includes at least one media output component  356  for use in presenting information to a user. Media output component  356  is any component capable of conveying information to the user. Media output component  356  may include, without limitation, a display device (not shown) (e.g., a liquid crystal display (LCD), an organic light emitting diode (OLED) display, or an audio output device (e.g., a speaker or headphones)). 
     In some embodiments, user computing device  350  includes an input interface  360  for receiving input from the user. Input interface  360  may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, and/or an audio input device. A single component, such as a touch screen, may function as both an output device of media output component  356  and input interface  360 . 
     During operation, a user may initially input a predefined threshold value for a power output from load  200  via input interface  360 . The predefined threshold value may be programmed with user computing device  350  and/or the controller  320 . When turbine engine  102  (shown in  FIG. 1 ) commences operation, mechanical rotational energy is generated. When the mechanical rotational energy is converted to electrical energy via load  200  for a power output, the output is detected by sensor  335 . Sensor  335  then transmits a signal representative of the power output to controller  320 . 
     Depending on whether the power output is less than, greater than, or equal to the predefined threshold, controller  320  will transmit a control parameter to the valve or switch. For example, in some embodiments, if the power output exceeds the predefined threshold, controller  320  will transmit a control parameter to the valve or switch such that electrical energy (i.e. power output) is channeled in second direction  284  towards energy storage device  130  such that the power output may be stored for later use by power system  100 . If the power output is below the predefined threshold, controller  320  may transmit a control parameter to the valve or switch such that electrical energy is channeled in first direction  282  towards turbine engine  102  such that the power output may be used by turbine engine  102  to generate additional power. 
     Due to the bi-directional capabilities of power system  100 , the high rotational speeds implemented by drive shaft  122  (shown in  FIG. 1 ) and/or rotor shaft  206  (shown in  FIG. 4 ) may vary or cause deviations. Such rotational variations and/or deviations may cause rotor shaft  206  and/or drive shaft  122  to undergo mechanical stress that results in a misalignment of rotor shaft  206 , rotor assembly  204  (shown in  FIGS. 2 and 4 ), and/or load  200  with respect to drive shaft  122  and/or turbine engine  102 . However, because rotor shaft  206  is coupled to drive shaft  122  via quill shaft  220  (shown in  FIG. 2 ), rotor shaft  206  is axially and/or radially isolated from drive shaft  122 . As such, there is rotordynamic isolation between load apparatus  128  and turbine engine  102 . Accordingly, mechanical stress and/or misalignment of rotor shaft  206  and/or load apparatus  128  with respect to drive shaft  122  and/or turbine engine  102  may be inhibited even when there is bi-directional power flow within power system  100 . 
       FIG. 6A  illustrates a portion of an alternative load apparatus  500  that can be used in place of load apparatus  128  (shown, in  FIGS. 1-5 ) and taken from area  6  (shown in  FIG. 2 ). For example,  FIG. 6A  illustrates a portion of a rotor assembly  502  that may be used in place of rotor assembly  204  (shown in  FIGS. 2 and 4 ) and a portion of a coupling or quill shaft  503  that may be used in place of quill shaft  220  (shown in  FIG. 2 ). 
     Rotor assembly  502  includes a substantially cylindrical rotor shaft  504 , wherein at least a portion of shaft  504  can be positioned within a sleeve apparatus, such as sleeve apparatus  208  (shown in  FIG. 4 ). In some embodiments, rotor shaft  504  includes a first end portion  506 , a main body portion or middle portion  516 , and a second end portion (not shown). Rotor shaft  504  can be positioned within sleeve apparatus  208  such that at least a portion of middle portion  516  is positioned within sleeve apparatus  208 , and first end portion  506  and the second end portion are not positioned within sleeve apparatus  208 . As such, rotor shaft  504  is configured to rotate within at least a portion of load  200  (shown in  FIG. 3 ). 
     In some embodiments, first end portion  506  of rotor shaft  504  has a diameter  507  that is substantially equal to the diameter  509  of middle portion  516 . Alternatively, first end portion  506  and middle portion  516  may each have diameters that are different from each other. First end portion  506  is configured to be removably coupled to quill shaft  503 . For example, in some embodiments, first end portion  506  includes an exterior surface  530  and opposing interior surface  532 . At least one extension portion, such as extension portions  534 , extend radially outwardly from exterior surface  530 . In some embodiments, extension portions  534  are each substantially rectangular. Alternatively, extension portions  534  can have any suitable shape that enables load apparatus  500  and/or power system  100  (shown in  FIG. 1 ) to function as described herein. Each extension portion  534  has a first end portion  536  and a second end portion  538  a predefined distance  540  from first end portion  536 , wherein distance  540  can be any suitable distance that enables load apparatus  500  and/or power system  100  to function as described herein. Extension portions  534  can be machined onto exterior surface  530 , via any processes and techniques known in the art, such that extension portions  534  are integrally formed with exterior surface  530 . In some embodiments, the second end portion of rotor shaft  504  can be identical in shape and structure as first end portion  506  of rotor shaft  504 . Alternatively, the second end portion of rotor shaft  504  can have a shape and structure that varies from first end portion  506  of rotor shaft  504 . 
     In some embodiments, first end portion  506  (including extension portions  534 ), middle portion  516 , and the second end portion or rotor shaft  504  are each formed of the same suitable material, such as the same type of metal material, and can be machined and integrally formed together, via any processes or techniques known in the art, such that rotor shaft  504  is a unitary component. Alternatively, first end portion  506  (including extension portions  534 ), middle portion  516 , and the second end portion can each be formed of the same suitable material or different suitable materials, such as different types of metals, and can be removably coupled to each other such that rotor shaft  504  is not a unitary component. 
     Quill shaft  503 , in some embodiments, is substantially cylindrical and also includes a first end portion  542 , a main body portion or middle portion  544 , and a second end portion (not shown). First end portion  542  of quill shaft  503  is configured to receive first end portion  506  of rotor shaft  504 . For example, first end portion  542  of quill shaft  503  includes an exterior surface  546  and an opposing interior surface  548 . At least one slot, such as slots  550 , extends from interior surface  548  and through exterior surface  546  and each slot  550  is configured to receive one corresponding extension portion  534  from rotor shaft  504  therein. First end portion  542  of quill shaft  503  has a diameter  543  that is greater than diameter  507  of first end portion  506  of rotor shaft  504  such that at least a portion of first end portion  506  of rotor shaft can be positioned within first end portion  542  of quill shaft  503 . When first end portion  506  of rotor shaft  504  is positioned within first end portion  542  of quill shaft  503 , then each extension portion  534  is positioned within a corresponding slot  550  such that each extension portion  534  extends radially outwardly from exterior surface  546  of quill shaft  503 . 
     In some embodiments, first end portion  542 , middle portion  544 , and the second end portion of quill shaft  503  are each formed of the same suitable material, such as the same type of metal, and can be machined and integrally formed together, via any processes known in the art, such that quill shaft  503  is unitary component. Alternatively, first end portion  542 , middle portion  544 , and the second end portion can each be formed of the same suitable material or different suitable materials, such as different types of metals, and can be removably coupled to each other such that quill shaft  503  is not a unitary component. 
     In some embodiments, diameter  543  of first end portion  542  is not equal to a diameter  556  of middle portion  544  of quill shaft  503 . Alternatively, diameter  543  of first end portion  542  is equal to diameter  556  of middle portion  544 . In some embodiments, middle portion  544  has a channel  560  defined therein such that middle portion  544  is substantially hollow. In other embodiments, middle portion  544  does not have a channel therein such that an interior portion  566  of middle portion  544  is substantially solid. 
     The second portion of quill shaft  503 , in some embodiments, is identical in shape and structure as first end portion  542  of quill shaft  503  and an end portion (not shown) of drive shaft  122  (shown in  FIG. 1 ) is identical to the shape and structure of first end portion  506  of rotor shaft  504  such that the second end portion of quill shaft  503  can couple to the end portion of drive shaft  122  in the same manner that first end portion  542  of quill shaft  503  couples to first end portion  506  of rotor shaft  504 . 
     The number of extension portions  534  from first end portion  506  of rotor shaft  504  and the number of slots  550  from first end portion  542  of quill shaft  503  can vary to any suitable number that enables load apparatus  500  and/or power system  100  to function as described herein so long as the number of extension portions  534  equals the number of slots  550 . For example, in some embodiments, first end portion  506  of rotor shaft  504  can have two extension portions  534  that are located 180 degrees apart from each other on exterior surface  530  of first end portion  506 . Similarly, first end portion  542  of quill shaft  503  can have two slots  550  that are located 180 degrees apart from each other such that each of the two slots  550  are configured to receive the corresponding extension portion  534  therein. 
     The use of extension portions  534  being positioned within corresponding slots  550  enables torque to be transmitted though quill shaft  503  to mitigate misalignment issues between rotor shaft  504  and drive shaft  122 . Moreover, when there are two extension portions  534  being used that are 180 degrees apart and two corresponding slots  550 , the torque transmitted is aligned with the central axis of quill shaft  503 . Moreover, having a hollow middle portion  544  for quill shaft  503  can be relatively lower in cost in that first end portion  542  and the second end portion of quill shaft  503  integrates with middle portion  544 . Having a hollow middle portion  544  offers the further benefit of not requiring any machining other than slots  550  so that the dimensions of middle portion  544  can be controlled precisely during manufacturing and trim balancing of quill shaft  503  can be minimized. 
     In some embodiments, the end portions, such as first end portion  542 , of quill shaft  503  and the end portions, such as first end portion  506 , of rotor shaft  504  can have their relationships reversed. For example, first end portion  506  of rotor shaft  504  can have the shape and structures of first end portion  542  of quill shaft  503  and vice versa to facilitate the coupling relationship as described above. 
       FIG. 6B  illustrates a portion of an alternative load apparatus  700  that can be used in place of load apparatus  128  (shown in  FIGS. 1-5 ) and taken from area  6  (shown in  FIG. 2 ). For example,  FIG. 6B  illustrates a portion of a rotor assembly  702  that may be used in place of rotor assembly  204  (shown in  FIGS. 2 and 4 ) and a portion of a coupling or quill shaft  703  that may be used in place of quill shaft  220  (shown in  FIG. 2 ). 
     Rotor assembly  702  includes a substantially cylindrical rotor shaft  704 , wherein at least a portion of shaft  704  can be positioned within a sleeve apparatus, such as sleeve apparatus  208  (shown in  FIG. 4 ). In some embodiments, rotor shaft  704  includes a first end portion  706 , a main body portion or middle portion  716 , and a second end portion (not shown). Rotor shaft  704  can be positioned within sleeve apparatus  208  such that at least a portion of middle portion  716  is positioned within sleeve apparatus  208 , and first end portion  706  and the second end portion are not positioned within sleeve apparatus  208 . As such, rotor shaft  704  is configured to rotate within at least a portion of load  200  (shown in  FIG. 3 ). 
     In some embodiments, first end portion  706  of rotor shaft  704  has a diameter  707  that is substantially equal to the diameter  709  of middle portion  716 . Alternatively, first end portion  706  and middle portion  716  may each have diameters that are different from each other. First end portion  706  is configured to be removably coupled to quill shaft  703 . For example, in some embodiments, first end portion  706  includes an exterior surface  730  and opposing interior surface  732 . At least one extension portion, such as extension portions  734 , extends radially outwardly from exterior surface  730 . In some embodiments, extension portions  734  are each substantially rectangular. Alternatively, extension portions  734  can have any suitable shape that enables load apparatus  700  and/or power system  100  (shown in  FIG. 1 ) to function as described herein. Each extension portion  734  has a first end portion  736  and a second end portion  738  a predefined distance  740  from first end portion  736 , wherein distance  740  can be any suitable distance that enables load apparatus and/or power system  100  to function as described herein. Extension portions  734  can be machined onto exterior surface  730 , via any processes and techniques known in the art, such that extension portions  734  are integrally formed with exterior surface. In some embodiments, the second end portion of rotor shaft  704  can be identical in shape and structure as first end portion  706  of rotor shaft  704 . Alternatively, the second end portion of rotor shaft  704  can have a shape and structure that varies from first end portion  706  of rotor shaft  704 . 
     In some embodiments, first end portion  706  (including extension portions  734 ), middle portion  716 , and the second end portion or rotor shaft  704  are each formed of the same suitable material, such as the same type of metal material, and can be machined and integrally formed together, via any processes or techniques known in the art, such that rotor shaft  704  is a unitary component. Alternatively, first end portion  706  (including extension portions  734 ), middle portion  716 , and the second end portion can each be formed of the same suitable material or different suitable materials, such as different types of metals, and can be removably coupled to each other such that rotor shaft  704  is not a unitary component. 
     Quill shaft  703 , in some embodiments, is substantially cylindrical and also includes a first end portion  742 , a main body portion or middle portion  744 , and a second end portion (not shown). First end portion  742  of quill shaft  703  is configured to receive first end portion  706  of rotor shaft  704 . For example, first end portion  742  of quill shaft  703  includes an exterior surface  746  and an opposing interior surface  748 . At least one slot, such as slots  750  extend from interior surface  748  and to exterior surface  746  such that each slot  750  does not extend through exterior surface  746  and is not visible from exterior surface  746 . 
     Each slot  750  is configured to receive one corresponding extension portion  734  from rotor shaft  704  therein. First end portion  742  of quill shaft  703  has a diameter  743  that is greater than diameter  707  of first end portion  706  of rotor shaft  704  such that first end portion  706  of rotor shaft can be positioned within first end portion  742  of quill shaft  703 . When first end portion  706  of rotor shaft  704  is positioned within first end portion  742  of quill shaft  703 , then each extension portion  734  is positioned within a corresponding slot  750  such that each extension portion  734  cannot extend through exterior surface  746  of quill shaft  703 . 
     In some embodiments, first end portion  742 , middle portion  744 , and the second end portion of quill shaft  703  are each formed of the same suitable material, such as the same type of metal, and can be machined and integrally formed together, via any processes known in the art, such that quill shaft  703  is a unitary component. Alternatively, first end portion  742 , middle portion  744 , and the second end portion can each be formed of the same suitable material or different suitable materials, such as different types of metals, and can be removably coupled to each other such that quill shaft  703  is not a unitary component. 
     In some embodiments, diameter  743  of first end portion  742  is not equal to a diameter  756  of middle portion  744  of quill shaft  703 . Alternatively, diameter  743  of first end portion  742  is equal to diameter  756  of middle portion  744 . In some embodiments, middle portion  744  has a channel  760  defined therein such that middle portion  744  is substantially hollow. In other embodiments, middle portion  744  does not have a channel therein such that an interior portion  766  of middle portion  744  is substantially solid. 
     The second portion of quill shaft  703 , in some embodiments, is identical in shape and structure as first end portion  742  of quill shaft  703  and an end portion (not shown) of drive shaft  122  (shown in  FIG. 1 ) is identical to the shape and structure of first end portion  706  of rotor shaft  704  such that the second end portion of quill shaft  703  can couple to the end portion of drive shaft  122  in the same manner that first end portion  742  of quill shaft  703  couples to first end portion  706  of rotor shaft  704 . 
     The number of extension portions  734  from first end portion  706  of rotor shaft  704  and the number of slots  750  from first end portion  742  of quill shaft  703  can vary to any suitable number that enables load apparatus  700  and/or power system  100  to function as described herein so long as the number of extension portions  734  equals the number of slots  750 . For example, in some embodiments, first end portion  706  of rotor shaft  704  can have two extension portions  734  that are located 180 degrees apart from each other on exterior surface  730  of first end portion  706 . Similarly, first end portion  742  of quill shaft  703  can have two slots  750  that are located 180 degrees apart from each other such that each of the two slots  750  are configured to receive the corresponding extension portion  734  therein. 
     The use of extension portions  734  being positioned within slots  750  enables torque to be transmitted though quill shaft  703  to mitigate misalignment issues between rotor shaft  704  and drive shaft  122 . Moreover, when there are two extension portions  734  being used that are 180 degrees apart and two corresponding slots  750 , the torque transmitted is aligned with the central axis of quill shaft  703 . Moreover, having a hollow middle portion  744  for quill shaft  703  can be relatively lower in cost in that first end portion  742  and the second end portion of quill shaft  703  integrates with middle portion  744 . Having a hollow middle portion  744  offers the further benefit of not requiring any machining other than slots  750  so that the dimensions of middle portion  744  can be controlled precisely during manufacturing and trim balancing of quill shaft  703  can be minimized. 
     In some embodiments, the end portions, such as first end portion  742 , of quill shaft  703  and the end portions, such as first end portion  706 , of rotor shaft  704  can have their relationships reversed. For example, first end portion  706  of rotor shaft  704  can have the shape and structures of first end portion  742  of quill shaft  703  and vice versa to facilitate the coupling relationship as described above. 
     As compared to known power systems that provide bi-directional power flow, the embodiments of a power system described herein include embodiments of a load apparatus that is able to facilitate bi-directional power flow within the power system and the load apparatus is coupled to a machine such that the load apparatus is rotordynamically isolated from the machine. In some embodiments, the load apparatus includes a load and a rotor assembly that is coupled to the load, wherein the rotor assembly includes a rotor shaft that is configured to rotate within at least a portion of the load. The load apparatus also includes the use of a coupling shaft, such as a quill shaft, that is configured to couple the rotor shaft to a drive shaft of the machine such that the rotor shaft is axially and/or radially isolated from the drive shaft to facilitate rotordynamic isolation between the load apparatus and the machine. Moreover, as described herein, the machining of various components of the load apparatus is cost effective. 
     Exemplary embodiments of systems, apparatus, and methods are described above in detail. The systems, apparatus, and methods are not limited to the specific embodiments described herein, but rather, components of each system, apparatus, and/or method may be utilized independently and separately from other components described herein. For example, each system may also be used in combination with other systems and is not limited to practice with only systems as described herein. Rather, the exemplary embodiment can be implemented and utilized in connection with many other applications. 
     Although specific features of various embodiments of the invention may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the invention, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.