Abstract:
A control system includes memory storing instructions and a processor configured to execute the instructions. The processor is configured to receive a first indication of a power grid voltage, receive a second indication of a power grid phase angle, receive a third indication of a generator voltage of power provided by a generator, and receive a fourth indication of a generator phase angle of power provided by the generator. The processor is configured to determine a voltage gap between the generator voltage and the power grid voltage and a time difference between the generator phase angle and the power grid phase angle. The processor is configured to generate a signal to cause the generator voltage and the generator phase angle to synchronize with the power grid voltage and the power grid phase angle, respectively.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates to power grids, and more particularly, to improving synchronization between a power generator and a power grid. 
         [0002]    Generators are frequently used to provide electricity for a power grid to power one or more loads. A generator may operate at a certain voltage amplitude, phase, and frequency based on operation of a turbine, such as a gas turbine, steam turbine, or another prime mover. For example, a turbine may provide rotational energy to a shaft that rotates within the generator. The shaft may rotate based on various settings of the turbine, such as an amount of air and fuel entering the turbine. To export power to the power grid, the power generated by the generator is controlled to synchronize with the power on the power grid, and a circuit breaker is closed to electrically couple the generator with the power grid. That is, parameters of the power generated by the generator, such as voltage amplitude, phase, and frequency provided by the generator may be controlled to fall within a range of respective parameters of the grid, such as the voltage amplitude, phase, and frequency, before closing the circuit breaker. 
         [0003]    Conventional systems may include synchronization schemes where voltages across the breaker are sensed and the generated voltage is adjusted to meet the grid voltage by sending digital on/off pulses to a voltage regulator to adjust the voltage and speed of the generator. These pulses are used to match the generator voltage and increases or decreases the speed of the turbine to match phase angle with the grid. However, hunting to find the speed of the turbine that corresponds to voltages and phase angles of the power grid may take a considerable amount of time, delaying synchronization. Further, the delay in the response time may be amplified during weak or dynamic grid resulting in manual intervention, which may take even more additional time to synchronize. Because it may take an increased amount of time to synchronize the generator power with the power grid, the grid may become overloaded or further destabilize resulting in an outage. Alternatively and/or additionally, the turbine may waste power during synchronization resulting in less efficient use of fuel. 
       BRIEF DESCRIPTION 
       [0004]    Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
         [0005]    In a first embodiment, a control system includes memory storing instructions, and a processor configured to execute the instructions and configured to receive a first indication of a power grid voltage, receive a second indication of a power grid phase angle, receive a third indication of a generator voltage of power provided by a generator, receive a fourth indication of a generator phase angle of power provided by the generator, determine a voltage gap between the generator voltage and the power grid voltage and a time difference between the generator phase angle and the power grid phase angle, and generate a signal to cause the generator voltage and the generator phase angle to synchronize with the power grid voltage and the power grid phase angle, respectively, based at least in part on the voltage gap and the time difference. 
         [0006]    In a second embodiment, a non-transitory computer-readable medium includes instructions configured to be executed by a processor of a control system, wherein the configured instructions cause the processor to receive an indication of a voltage phase angle of power on a power grid, receive an indication of a voltage phase angle of power provided by a generator, determine a time difference between the generator voltage phase angle and the power grid voltage phase angle, send a first signal to control the generator voltage phase angle based at least in part on the time difference, and send a signal to a circuit breaker to close the circuit breaker when the time difference is within a tolerance, thereby electrically coupling the power grid to the generator. 
         [0007]    In a third embodiment, a method includes receiving, via a processor, a power grid signal indicating a power grid voltage of power on a power grid, receiving, via the processor, a generator signal indicating a generator voltage of power provided by a generator, determining, via the processor, a voltage gap between the generator voltage and the power grid voltage, and sending, via the processor, a signal to adjust a controller that controls the generator voltage to cause the generator to synchronize based on a magnitude of the voltage gap. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0009]      FIG. 1  is a block diagram of a synchronization system having a control system that synchronizes power provided by a generator with power on a power grid; 
           [0010]      FIG. 2  shows a graph of data received by the control system from the power grid and the generator of  FIG. 1 ; and 
           [0011]      FIG. 3  is a flow diagram of a process performed by a processor of the control system of  FIG. 1  to synchronize power provided by the generator with power on the power grid. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
         [0013]    When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
         [0014]    Embodiments of the present disclosure are related to systems and methods to reduce synchronization delay when closing a breaker that couples power from a generator with power on an unstable power grid. Conventionally, generators may be synchronized to a power grid based on digital pulses to increase or decrease speed of the turbine and/or excitation of the generator. Based on the pulses, the turbine and/or the generator may adjust settings (e.g., the flow of the air and the fuel) to bring a voltage magnitude and phase angle of power provided by the generator within a range of a voltage and phase angle of power on the power grid. For example, in the event that the grid is unstable, micro-oscillations of voltages and phase angles of the power grid may cause an increase in the time it takes to search for voltages and phase angles that synchronize the power provided by the generator with the power of the power grid. Because it may take an increased amount of time to synchronize the generator power with the power grid, the grid may become overloaded or further destabilize resulting in an outage. Alternatively and/or additionally, the turbine may waste power during synchronization resulting in less efficient use of fuel. 
         [0015]    A control system may be used to address the delay in synchronizing a generator to within voltage and frequency tolerances that enable the generator to electrically couple to a power grid. The control system may receive a power grid signal from a power grid voltage sensing transformer coupled to the power grid that indicates a voltage and a phase angle (e.g., voltage phase angle) of power on the power grid. The control system may receive a generator signal from a generator voltage sensing transformer coupled to a power line extending from the generator that detects a voltage and phase angle (e.g., voltage phase angle) of power provided by a generator. The control system may synchronize the voltage and phase angle of power provided by the generator by calculating a voltage gap between the power grid voltage and the generator voltage and by calculating a time gap between the phase angle of the power grid and the phase angle of power provided by the generator. The control system may then send a signal to an automatic voltage regulator to control speed of the turbine and/or excitation of the generator based on the calculated voltage gap and time gap. 
         [0016]    By way of introduction,  FIG. 1  is a diagram of a power synchronization system  10  that includes a gas turbine  12  having a compressor  14 , combustor  16 , and turbine  18 . The gas turbine  12  may receive air  20  to be compressed by the compressor  14 . The compressed air is mixed with fuel  22  and the air-fuel mixture is combusted in the combustor  16 . The combustion mixture of air and fuel may be used to rotate one or more blades of the turbine  18 . A rotor of the turbine  18  may be coupled to a shaft  24  to provide rotational energy to a generator  26 . While a gas turbine  12  is described above, any power generation system (e.g., steam or another prime mover) that generates power may be suitable to be used in accordance with embodiments described herein. 
         [0017]    The generator  26  converts rotational energy of the shaft  24  into electricity to provide power to a power grid  28 . The power grid  28  and/or the generator  26  may each operate at a nominal voltage, such as 10.5 kilovolts (kV) or less, 11 kV, or 11.5 kV or greater. The generator  26  may be electrically coupled to and decoupled from the power grid  28  by closing a circuit breaker  30  and/or electrically decoupled by opening the circuit breaker  30 . To ensure stability of connection to the power grid  28 , operational characteristics of the gas turbine  12  and/or the generator  26  may be synchronized with power characteristics of the power grid  28 , prior to closing the circuit breaker  30 . Additional considerations, such as a number of phases, a rotation of the phases, a voltage window, a frequency window, and a phase angle window may be considered to enable synchronization and thereby to enable closure of the circuit breaker  30 . Moreover, the number of phases and the rotation of the phases may be verified at the time of equipment selection. A voltage amplitude, phase, and/or frequency of power provided by the generator  26  that corresponds to physical characteristics of the gas turbine  12  (e.g., rotation, torque, etc) may be adjusted to match a voltage amplitude, phase, and/or frequency of the power grid  28  by adjusting the inputs to the gas turbine  12 , such as the air  20  and fuel  22 . When the voltage amplitude, phase, and/or frequency produced by the generator  26  are within an approved range (e.g., within the voltage window, frequency window, and/or phase window) of the voltage amplitude, phase, and frequency of the power grid  28 , then a control system  32  sends a signal that closes the circuit breaker  30 . 
         [0018]    As previously noted, the voltage and phase of the power grid  28  and the generator  26  may be synchronized within the allowable range prior to closing the circuit breaker  30 . The voltage characteristics provided by the generator  26  may be controlled, via an automatic voltage regulator (AVR)  42 , by changing a generator excitation voltage (e.g., by controlling the magnetic field of the generator). The AVR  42  setting of 1 per unit (PU) may be derived from the nominal grid voltage. Moreover, the phase angle of the power grid  28  and the phase angle of the power generated by the generator  26  may be synchronized (e.g., approximately matched) by controlling a speed of the gas turbine  12  (e.g., via the air  20  and fuel  22 ). In some systems, the voltages and phase angles may be controlled by a digital synchronizer module (DSM) that sends digital pulse signals to the prime mover speed governor to hunt for the desired voltage level by incrementing voltages and/or phase angles of the generator until the desired voltages and/or phase angles are found. For example, the DSM may send pulses to change the speed of the gas turbine  12  in the direction of the closest phase coincidence. With respect to the voltage window, the DSM may send pulses to change the generator excitation voltages. However, when the power grid  28  is unstable (e.g., where voltage fluctuation is more likely than a stable gird), achieving the desired voltage window and phase angle window based on pulses in a control loop may cause delays. Further, the delays may involve an operator or grid dispatcher intervening or changing the AVR  42  settings to reach the desired voltages and/or phase angles due to the pulses not accounting for the fluctuations in the unstable grid. 
         [0019]    To reduce delays in synchronizing the voltages and/or phase angles, the power synchronization system  10  may include the control system  32  that has a processor  34  or multiple processors and memory  36 . The processor  34  may be operatively coupled to the memory  36  to execute instructions for carrying out the presently disclosed techniques. These instructions may be encoded in programs or code stored in a tangible non-transitory computer-readable medium, such as the memory  36  and/or other storage. The processor  34  may be a general-purpose processor, system-on-chip (SoC) device, application-specific integrated circuit, or some other processor configuration. 
         [0020]    Memory  36  may include any non-transitory, computer readable medium, such as, without limitation, a hard disk drive, a solid state drive, a diskette, a flash drive, a compact disc (CD), a digital video disc (DVD), random access memory (RAM), and/or any suitable storage device that enables processor  34  to store, retrieve, and/or execute instructions and/or data. Memory  36  may further include one or more local and/or remote storage devices. 
         [0021]    The control system  32  may be programmed or configured (e.g., performed via the processor  34  and the memory  36 ) to receive one or more signals via a power grid voltage sensing transformer (VT)  38  that detects power characteristics of the power grid  28  and a generator voltage sensing transformer (VT)  40  that detects power characteristics of the power provided by the generator  26 . For example, the processor  34  may receive signals, via the power grid VT  38  and generator VT  40 , indicating the voltage magnitude, phase, and/or frequency of power on the power grid  28  and the generator  26 , respectively. The processor  34  may receive sample values of the voltages of the power grid VT  38  and/or generator VT  40  at a sample rate that avoids signal aliasing (e.g., greater than 8 times per cycle). Further, to ensure steady samples, the processor  34  may receive a sample for a preset time or number of cycles (i.e., periods), such as one, two, five, ten, or more cycles. For instance, five cycles at 50 hertz may take approximately 100 milliseconds (ms). The processor  34  may convert the received sample values into coordinates associated with a voltage value at a time value (V, T). 
         [0022]    The control system  32  may be communicatively coupled to the AVR  42  and a human machine interface (HMI)  44 . The HMI may include a display and/or other inputs and outputs to enable an operator to select options/values, such as the tolerance limits of the voltage window, phase angle limits of the phase angle window, or the like. Further, the HMI may allow data of signals received by the control system  32  to be viewed. The control system  32  may be communicatively coupled, via Ethernet, wireless connection, or any other suitable method. 
         [0023]      FIG. 2  shows a graph  48  of an example of generator waveform  52  representing a variation of voltage over time and a grid waveform  54  representing a variation of voltage over time during a cycle over time  50 . The processor  34  may receive the voltages on the power grid  28  via the power grid VT  28  and the voltages provided by the generator  26  via the generator VT  40 . Although the graph  48  may be displayed on a display associated with the control system  32 , the AVR  42 , or the HMI  44 , the graph  48  is meant to be illustrative, and the data may simply be processed by the processor  34  without being displayed. As shown in the graph  48 , each coordinate falling on waveforms  52  and  54  may be determined by the processor  34  from each sample and may include a voltage and time value of the generator waveform  52  and/or the power grid waveform  54 . Corresponding values of the waveforms may be used, for instance, to calculate a difference between the power grid voltage and the generator voltage for corresponding points (e.g., zero crossing, time, voltage, etc). 
         [0024]      FIG. 3  shows a process  56  for synchronizing the gas turbine with the power grid so that the beaker may be closed.  FIG. 3  is discussed below in conjunction with the graph  48  of  FIG. 2 . Process  56  described below may be stored in the memory  36  of the control system  32  as instructions executed by the processor  34  (e.g., running code). At block  58 , the processor  34  may begin by adjusting an AVR  42  setpoint to be V grid  so that the generator  26  is configured to meet a desired voltage of the power grid  28 . 
         [0025]    At blocks  60  and  62 , the processor  34  may collect a power grid VT  38  data sample and a generator VT  40  data sample, respectively. For example, as shown in  FIG. 2 , the processor  34  may receive a signal indicating a power grid voltage corresponding to a coordinate  64  (V 2,  T 1  ) and a signal indicating a generator voltage corresponding to a coordinate  66  (V 1 , T 1  ). At blocks  68  and  70 , the processor  34  may then respectively store the V  grid  samples and the V gen  samples in data arrays. 
         [0026]    Further, at block  72 , the processor  34  may continue to collect samples until a preset threshold number of samples has been reached. For example, if the control system  32  is configured to measure a number (e.g., eight) samples per cycle for a number cycles, then the processor  34  may continue collecting samples from each of the power grid VT  38  and the generator VT  40  until a threshold number (e.g., forty) samples are measured. Although the process  56  shows blocks  60  and  68  in parallel with blocks  62  and  70 , in some embodiments, these steps may be performed sequentially rather than simultaneously. For example, blocks  60  and  68  may precede blocks  62  and  70  or vice versa. 
         [0027]    When the preset threshold has been reached at block  72 , the processor  34  may then calculate a voltage gap between the V grid  samples and the V gen  samples. From the graph  48 , the following equation may be derived: 
         [0000]      Voltage Gap( V   gap )= V   2   −V   1   =V   grid   −V   gen    (1)
 
         [0000]    where V 2  is the power grid voltage at time T 1  and V 1  is the generator voltage at time T 1 . Further, for the preset number of cycles, the samples may be used for a root means square (RMS) calculation where average electrical power of V gap  is calculated at block  74 : 
         [0000]        V   gap =RMS( V   grid,i )−RMS( V   gen,i )   (2)
 
         [0000]    where i is the sample number. 
         [0028]    At block  76 , the processor  34  may receive a tolerance or percentage threshold voltage (Vd %) value that is an accepted tolerance between V gen  and V grid . While the process  56  includes receiving a selection of the tolerance value via the HMI  44 , in other embodiments, the processor  34  may simply have a default preset value (e.g., 1%, 3%, or 5%). Further, in some embodiments, the processor  34  may receive, via the HMI  44 , an adjusted value when an operator changes the default value to customize the tolerance based on system configurations. 
         [0029]    At block  78 , the processor  34  may determine whether the V gen  value is greater than the tolerance level of the V grid  value. If V gen  is greater than the tolerance value (Vd %) with respect to the V grid , the processor  34  also determines timing tolerance thresholds, as discussed below. If both the timing thresholds and the voltage thresholds are met (block  80 ), then the processor  34  may send signals to close the breaker  30  at block  82 . 
         [0030]    At block  83 , if the voltage threshold has not been met, the processor  34  may send a signal to the AVR  42  to adjust a generator voltage based on V gap . For example, the processor  34  may send the adjusted generator voltage, via Ethernet, for the AVR  42  to account for the voltage difference between the power grid  28  and the generator  26 . That is, instead of hunting or searching to match the generator voltage with the voltage of the power grid  28 , the processor  34  may determine the difference between the voltage of the generator  26  and the voltage of the power grid  28 , thereby reducing an amount of time to adjust the voltages provided by the generator  26  for synchronization. 
         [0031]    At block  84 , the processor  34  may send signals to the AVR  42  to update the proportional-integral-derivative (PID) gain of the AVR  42  during the synchronization process. That is, the control system  32  may enable a faster voltage response in the AVR  42  by adjusting the PID gain factors during the synchronization process to achieve a faster synchronization than using preset values in the PID controller. For example, the proportional (KPR) and integral (KIR) gains of the AVR  42  PID control will be dynamically adjusted to increase or decrease a voltage ramp rate. By changing the PID control factors of the AVR  42 , the reaction time of decreasing the error between the voltage provided by the generator  26  and the voltage of the power grid  28  may be reduced as compared to using constant values as gain factors. As such, the control signals sent by the processor  34  to the AVR  42  that control the generator  26  may enable faster synchronization with the power grid  28  as compared an AVR  42  that uses preset gain factors. 
         [0032]    The processor  34  may update KPR and KIR factors based on the generator voltage and send a signal to the AVR  42  indicating the updated KPR and KIR factors. The processor  34  may utilize a lookup table to control gain values that are used to adjust the AVR response rate. Table 1 below is an example of values that may be used to adjust the AVR response rate. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Gain Factors 
               
             
          
           
               
                   
                 Small 
                   
                   
                   
                   
                   
                 Large 
               
               
                   
                 Difference 
                   
                   
                 Nominal 
                   
                   
                 difference 
               
               
                   
                   
               
             
          
           
               
                 KPR 
                 15 
                 22 
                 28 
                 20 
                 36 
                 43 
                 50 
               
               
                 KIR 
                 15 
                 19 
                 23 
                 20 
                 25 
                 31 
                 35 
               
               
                   
               
             
          
         
       
     
         [0033]    The AVR  42  may then receive the KPR and KIR values to adjust the AVR response rate. Based on the received values, the AVR  42  may send signals to generator excitation circuit to rapidly increase or decrease excitation of the generator, thereby controlling the voltage provided by the generator  26 . For example, if the difference between the voltage on the power grid and the voltage provided by the generator is a small difference, then the processor  34  may send a lower value of KPR and KIR to be used in the PID controller to reduce likelihood of overshooting a target voltage while reducing the difference between the voltages of the grid and generator. Conversely, if the difference between the power grid and generator voltages is larger than the small difference, then the processor  34  may send a larger KPR and KIR value to be used by the AVR to more aggressively reduce the difference (as compared to the small difference). That is, the processor  34  may send a signal that adjusts the PID controller of the AVR  42  to cause the generator  26  to synchronize based on a magnitude of the voltage gap where the magnitude of the voltage gap is proportional to the gain values selected from the lookup table. By sending signals to adjust the PID settings of the AVR  42 , the processor  34  may enable the power generated by the generator  26  to synchronize at a faster rate than pulse techniques that search for matching voltages. 
         [0034]    At block  85 , the processor  34  may identify a zero crossing time based on the samples of coordinates that correspond to times that the voltage of the power grid  28  and the voltage provided by the generator  26  are zero (i.e., times where V grid  and V gen =0). For example, as shown in  FIG. 2 , the processor  34  may identify coordinate  86  (V 0 , T b ) and coordinate  88  (V 0 , T a ) as the zero crossing time of the power grid waveform  54  and the generator waveform  52 , respectively. Further, at block  90 , the processor  34  may calculate a phase shift, where the phase shift (T b -T a ) is a time difference between when the voltage of the power grid crosses the zero voltage line (T b ) and when the voltage provided by the generator crosses the zero voltage line (T a ). 
         [0035]    At block  92 , the processor  34  may receive a selection of a phase angle (e.g., Φ) that indicates a tolerance between the phases of the power grid  28  and the generator  26 . In some embodiments, the value may preset as received from a user via the HMI  44 . At block  94 , the processor  34  may convert the phase angle into a time threshold (T d ) using the following equation: 
         [0000]    
       
         
           
             
               
                 
                   
                     T 
                     d 
                   
                   = 
                   
                     360 
                     
                       Φ 
                       * 
                       F 
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
         [0000]    where Φ is the received phase angle in degrees and F is the frequency of the shaft  24 . 
         [0036]    Then, the processor  34  may compare the time of the generator T gen  to the time threshold T d . If T gen  is greater than or equal to the threshold T d  (block  96 ) and V gen  is greater than Vd % (block  80 ), then the processor  34  may send a signal to perform the breaker closure at block  82 . If T gen  is not greater or equal to T d  and Vd %, then the processor may adjust the generator speed, as discussed below. 
         [0037]    At block  98 , the processor  34  may calculate a desired change in RPM speed (dSpeed). As described below, to compensate for the phase shift, the turbine speed may be increased or reduced based on a calculated RPM. 
         [0000]    
       
         
           
             
               
                 
                   RPM 
                   = 
                   
                     
                       120 
                       * 
                       F 
                     
                     
                       # 
                        
                       
                           
                       
                        
                       of 
                        
                       
                           
                       
                        
                       Poles 
                     
                   
                 
               
               
                 
                   ( 
                   4 
                   ) 
                 
               
             
           
         
       
     
         [0000]    where the RPM is the revolutions per minute of the shaft  24  within the generator  26 . From equation (4), if the generator  26  is a two pole generator  26 , then the following equation may be derived: 
         [0000]    
       
         
           
             
               
                 
                   RPM 
                   = 
                   
                     120 
                     
                       T 
                       * 
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   5 
                   ) 
                 
               
             
           
         
       
     
         [0000]    where T is the time period ( 1 /F). As such, the desired change in RPM speed may be determined by the following equation: 
         [0000]    
       
         
           
             
               
                 
                   RPM 
                   = 
                   
                     120 
                     
                       
                         ( 
                         
                           
                             T 
                             b 
                           
                           - 
                           
                             T 
                             a 
                           
                         
                         ) 
                       
                       * 
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   6 
                   ) 
                 
               
             
           
         
       
     
         [0038]    At block  100 , the control system  32  may then send a signal to the gas turbine  12  to adjust the generator RPM speed based on the current generator RPM speed (NSDRef) and the desired change in RPM speed. For example, the control system  32  may send the adjusted generator RPM speed setting to the speed governor to account for a difference between the phase angle of the generator  26  and the phase angle of the voltage of the power grid  28 . That is, instead of hunting or searching to match the generator phase with the phase of the power grid  28 , the processor  34  may determine the difference between the phase angle of the generator  26  and the phase angle of the power grid  28 . Then, the processor  34  may send signals to the speed governor indicating the adjusted generator RPM settings to reduce an amount of time to adjust the turbine speed for synchronization, thereby reducing the time to close the breaker  30 . 
         [0039]    Technical effects of the invention include sending signals to an automatic voltage regulator (AVR) and speed governor to control a generator and gas turbine to synchronize power provided by the generator with power on a power grid. In some embodiments, a control system receives voltages and phase angles from a power grid and a generator. In certain embodiments, the control system determines a voltage gap between the generator voltage and the power grid voltage and a time difference between the generator phase angle and the power grid phase angle. In some embodiments, the control system may send a signal to regulate the generator voltage and the generator phase angle of the power provided by the generator based on the voltage gap and the time difference. By sending signals to the AVR, the speed of the gas turbine may be controlled to synchronize with the power grid. 
         [0040]    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.