Abstract:
There is provided a method for operating a control module of a high voltage switch, the method comprising: interfacing with an external environment via an input/output unit that filters each electrical signal passing therethrough; analyzing incoming signals and triggering actions as a function of the incoming signals via a logical unit; powering the control module via an internal power unit that is supplied by an external power supply; and isolating the logical unit from the power unit and the input/output unit by having all signals coming from these units and directed to the logical unit pass through an isolation unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is the first application filed for the present invention. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to the field of the supervision, control and protection of a high voltage electrical substation. 
       BACKGROUND OF THE INVENTION 
       [0003]    An electrical substation is a subsidiary station of electricity generation, transmission and distribution where voltage is transformed from high to low or vice-versa using transformers. Electrical substations are usually provided with a control module which monitors and controls the different elements and functions of the substation. These elements comprise disconnectors, disconnect switches, circuit breakers and other high voltage switch gears. As electrical substations are operated with high voltage, the control modules have to be protected and isolated from this high voltage so that the components of the control module will not be damaged by electromagnetic interferences (EMIs) or radio frequency interferences (RFIs). 
         [0004]    The protection of control modules is limited to voltage surges of the order of 1000-1500 V. Therefore, there is a need to provide control modules that safely operate in environments of higher voltage surges. 
       SUMMARY OF THE INVENTION 
       [0005]    According to a first broad aspect of the present invention, there is provided a system for controlling a high voltage switch comprising: an input/output unit comprising a filtering system for each of a plurality of electrical signals passing through the input/output unit; a logical unit comprising a memory and a first processor, and adapted to be connected to an external power supply; an isolation unit comprising an isolation system for each of the plurality of electrical signals and for a voltage signal, the input/output unit, the isolation unit and the logical unit being electrically connected to transmit signals received by the input/output unit to the logical unit through the isolation unit and to transmit externally signals generated by the logical unit through the isolation unit and the input/output unit; and a power unit comprising a power board and a filter and isolation sub-unit, and adapted to be connected to the external power supply, the power unit being adapted to supply in power the input/output unit and the isolation unit through the filtering and isolation sub-unit, the high voltage switch and the power unit being electrically connected to the isolation unit to receive the voltage signal. 
         [0006]    According to a second broad aspect of the present invention, there is provided a method for operating a control module of a high voltage switch, the method comprising: interfacing with an external environment via an input/output unit that filters each electrical signal passing therethrough; analyzing incoming signals and triggering actions as a function of the incoming signals via a logical unit; powering the control module via an internal power unit that is supplied by an external power supply; and isolating the logical unit from the power unit and the input/output unit by having all signals coming from these units and directed to the logical unit pass through an isolation unit. 
         [0007]    It should be understood that the term “switch” is to include any type of disconnector, disconnect switch, circuit breaker, or switch gear that serves to open and close a circuit at high voltage. 
         [0008]    It should be understood that the term “processor” is used to represent any circuit which can process data and/or signals. Central processing unit (CPU), microprocessors, and microcontrollers are examples of processors. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0010]      FIG. 1  is a block diagram of an embodiment of the control module comprising four units; 
           [0011]      FIG. 2   a  is a graph of the voltage applied to a disconnect switch as a function of the location of the disconnect switch in which the rising edge of the curve has a logarithmic shape, in accordance with an embodiment of the present invention; 
           [0012]      FIG. 2   b  is a graph of the voltage applied to a disconnect switch as a function of the location of the disconnect switch in which the rising edge of the curve has an exponential shape, in accordance with an embodiment of the present invention; 
           [0013]      FIG. 3  is a graph of the current as a function of location, in accordance with an embodiment of the present invention; 
           [0014]      FIG. 4  illustrates an embodiment of the electrical circuit of the input/output unit for a signal entering the control module; and 
           [0015]      FIG. 5  is a block diagram of an embodiment of the control module comprising five units. 
       
    
    
       [0016]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0017]    The present control module is a system that monitors and controls any switch present in a high voltage environment and comprising an hydraulic, pneumatic or electromechanical. The control module enables the monitoring and the control of any system having motors, valves or pieces of equipment having any kind of movement such as a linear or rotary movement. For example, the control module operates a real time control of the opening and/or closing speed of a switch. The control module controls the opening or closing speed of the switch by varying the voltage applied to the switch. For example, the voltage can be applied to the motor controlling the arm of a disconnect switch or it can be applied to a pump controlling the gas/liquid pressure of circuit breaker. 
         [0018]    The control module may control many aspects of the operation including, but not limited to, internal environmental conditions (such as temperature and humidity levels), a switch, alarms, inputs and outputs, internal tests, and information management. 
         [0019]    According to an embodiment of the control module, the control module is protected from voltage surges of about 5000 V. 
         [0020]    Particularly, the control module can control and adjust parameters such as the location of the arm of a disconnect switch or the gas/liquid pressure in a circuit breaker. Additionally, the control module can also control the temperature and/or humidity of the air in the control module. 
         [0021]    The control module can communicate with its external environment which may include other control modules, operators, computers, sensors, pieces of equipments, etc. 
         [0022]    In an embodiment, the control module comprises  4  units: a power unit, a logical unit, an input/output unit, an isolation unit, as illustrated in  FIG. 1 . The power unit receives the power supply external to the control module and supplies the other units in power, except the logical unit which is supplied directly by the external power supply. This unit also supplies in power the switch to be controlled by the control module. 
         [0023]    In an embodiment, the power unit comprises a power driver and a filtering and isolation sub-unit. The power driver is supplied by the external power supply and supplies the switch to be controlled, the isolation and the input/output unit in power through an isolation and filtering sub-unit. The isolation and filtering realized by the filtering and isolation sub-unit can be obtained using any technique known to a person skilled in the art. 
         [0024]    In an embodiment of the control module, the power unit and the logical unit are supplied by an AC current and the power unit generates AC currents to supply the different elements to be controlled and the other units of the control module. 
         [0025]    In another embodiment, the power unit and the logical unit are be supplied by a DC current and the power unit generates DC currents to supply the different elements to be controlled and the other units of the control module. One skilled in the art would appreciate that the control module can be supplied by an electrical generator. 
         [0026]    Referring to  FIG. 1 , the input/output unit represents the interface between the control module and the external environment. In an embodiment, the inputs received by the input/output unit include, but are not limited to, the signals coming from an operator, signals coming from other control modules and/or pieces of equipment and signals coming from sensors. For example, the signals coming from the operator can be signals ordering the control module to open or close the switch or signals asking information about the control module or the switch. For example, the signals coming from other control modules and/or pieces of equipment can provide information about other switches, other control modules. They can also be alarm signals. The signals coming from sensors indicate the performances of the piece of equipment to be controlled. For example, the performances can include a pressure, a position or a current intensity. 
         [0027]    In an embodiment, the signals coming from the sensors go directly to the isolation unit without passing through the input/output unit. 
         [0028]    The input/output unit also transmits signals directed towards the operator or other control modules and/or pieces of equipment of the substation. For example, the transmitted signals can be alarm signals or signals indicating the performances of the control module or the switch. Furthermore, the input/output unit executes the function of filtering the entering and exiting signals, isolating the control module from the external medium and protecting the control module from over-voltage. 
         [0029]    The logical unit analyses the control signals coming from the sensors, the command signals coming from the operator and the signals coming from the other control modules and/or pieces of equipment, takes decisions whether the voltage of the switch to be controlled has to be adjusted or not and sends signals. The signals sent by the logical unit include communication signals internal to the control module and signals directed to the external environment. Signals indicating a voltage to be applied to the switch are examples of internal communication signals. The analysis of the signals and the taking of decisions is performed by a processor. For example, if a voltage has to be varied, the logical unit communicates to the power unit through the isolation unit the voltage that has to be applied. 
         [0030]    In an embodiment, the logical unit can also communicate with an external computer and the communication signal passes through the isolation unit before reaching or after leaving the logical unit. 
         [0031]    In an embodiment, the processor can store about 5 measurements per second during a long period of time. 
         [0032]    Referring to  FIG. 1 , the isolation unit isolates the logical unit from the power unit and the input/output unit. All signals entering or exiting the logical unit pass by the isolation unit. The isolation unit ensures the security of the logical unit against EMIs and/or RFIs. 
         [0033]    The isolation module which isolates the logical unit from the remaining of the control module can be of any kind known by a person skilled in the art. The isolation offered by this module can be optical, mechanical and/or galvanic. 
         [0034]    According to an embodiment, the control module can receive numerical or analog signals. 
         [0035]    In an embodiment, the control module receives current signals in the range of 4-20 mA and protects them. 
         [0036]    In an embodiment, the control module further comprises sensors which monitor its environmental conditions of operation such as the temperature and the humidity. Additionally, the control module can adjust the temperature and/or the humidity of the cage comprising the control module. In this case, the sensors communicate with the logical unit through the isolation unit. The logical unit takes decisions to whether or not the temperature and/or the humidity have to be adjusted. If so, the logical unit communicates the voltage to be applied to the heating system and/or air conditioning system and/or humidifier and/or dehumidifier and/or fan to the power unit through the isolation unit. The sensors can be located anywhere in the control module. For example, the sensors can be placed in the power unit and, in this case, the signals sent by the sensors to the processor passes through the isolation and filtering subunit before reaching the isolation unit. 
         [0037]    In an embodiment, the power unit can be supplied by a voltage in the range of 50 to 240 V either in DC or AC current conditions and can generate DC or AC voltages, respectively, in the same range to control the different switches of the substation. 
         [0038]    In an embodiment, the operational ranges of the control module are from 90 to 250 V under AC conditions and from 80 to 160 V under DC conditions. 
         [0039]    The logical unit comprises a processor which analyses the received data coming from sensors. These sensors monitor an operating parameter and the performances of the piece of equipment to be controlled. For example, the operating parameter can be the position of the arm of a disconnect switch or the gas/liquid pressure in the case of a circuit breaker. The processor stores the data and takes the decision to adjust or not the voltage applied to the piece of equipment. For example, if the piece of equipment is a disconnect switch controlled by a motor, the logical module will decide the voltage that has to be applied to the motor after receiving the order to open the disconnect switch. 
         [0040]    When the processor receives the order to vary an operating parameter of the piece of equipment to be controlled, the first step taken by the processor is the reading of the operating parameter. The different values that the operating parameter has to take in order to achieve the variation are stored in a memory. The processor reads the first value to be given to the operating parameter and transmits the voltage corresponding to the first value of the operating parameter to the power unit through the isolation unit. The power unit applies the voltage to the piece of equipment. The sensor monitoring the operating parameter continuously transmits the value of the operating parameter to the processor. When the processor notices that the monitored value of the operating parameter corresponds to the first value of the operating parameter, the processor reads the second value to be given to the operating parameter stored in the memory and transmits the corresponding voltage to the power unit which applies it to the piece of equipment. When the monitored operating parameter corresponds to the second value of the operating parameter, the processor reads the third value to be given to the operating parameter and transmits the corresponding voltage to the power unit. These steps are repeated until the task has been completed. These steps gives a plurality of speeds to the opening or closing of the switch and the speed depends on the type of switch being operated. 
         [0041]    According to an embodiment, the location of an arm of a motorized disconnect switch is controlled by the control module. A sensor indicates the location of the arm to the logical unit. The control module receives the order to open the disconnect switch. The processor reads the first position of be given to the arm in the database stored in the memory and consequently transmits the corresponding voltage to the power unit which applies it to the motor of the disconnect switch. The motor moves the arm of the disconnect switch. When the position monitored by the sensor corresponds to the target position, the processor reads the second value to be given to the arm and its corresponding voltage is transmitted to the power unit which applies it to the motor of the disconnect switch. These steps are repeated until the disconnect switch is completely open. These steps gives a plurality of speeds to the arm and the speed depends on the position of the arm, whether it is opening or closing. 
         [0042]      FIG. 2   a  illustrates the voltage applied to a disconnect switch as a function of the location of arm of the disconnect switch. The voltage is represented in percentage so that when a voltage of 0% is applied, the switch does not move. The points  102  are the different values of the location of the arm stored into the memory, for which a corresponding voltage is also stored in the memory. The processor reads successively the points  102  and transmits the corresponding voltage to be applied to the power unit. When the arm has reached a position corresponding to one of the points  102 , the processor reads the next position value which corresponds to the next point  102  and transmits its corresponding voltage to be applied. The dashed line  104  represents the voltage curve that has to be applied to the switch. The line  106  is the voltage curve obtained by using the method described above. 
         [0043]      FIG. 2   a  illustrates an embodiment of the closing of a disconnect switch. A high speed is immediately set and the arm moves quickly to reduce the duration of the arc being formed between the moving contact and the fixed contact of the switch. The speed is decreased when the arc is cut, which occurs when the moving contact comes into contact with the fixed contact. The arm is stopped when the fully closed position is reached. 
         [0044]      FIG. 2   b  illustrates another curve of voltage applied to another disconnect switch as a function of the location of the switch. As in  FIG. 2   a,  the voltage is represented in percentage. The points  110  are the positions stored into the memory. When the arm has reached one this position, the processor reads the next one and applies the corresponding voltage through the power unit. The dashed line  112  represents the voltage curve that has to be applied to the switch. The line  114  is the voltage curve obtained by using the method described above. 
         [0045]      FIG. 2   b  illustrates an embodiment of an opening of a disconnect switch. A first speed is set until the point when an arc forms between the moving contact and the fixed contact. At this moment, the arm is accelerated significantly until the arc breaks, after which the arm is decelerated until a fully open position. A brake may be activated to stop the arm completely. 
         [0046]      FIGS. 2   a  and  2   b  illustrate how the curve of the voltage can be easily designed using the algorithm which consists in varying the voltage as a function of the position of the arm in order to vary the speed of the arm. In  FIG. 2   a,  the rising edge of the curve  106  has a logarithmic shape where the rising edge of the curve  114  has an exponential shape in  FIG. 2   b.    
         [0047]    It should be understood that the curve of the voltage can have any shape by using the method described above. It should be noted that the method above presented for the opening or closing of the arm of a disconnect switch is not restricted to a disconnect switch and can be apply to control the opening and closing speed of any type of switch present in an electrical substation. 
         [0048]    According to an embodiment, the processor can also have a function of prediction of tear and wears. By only analyzing the evolution of additional operating parameters of the piece of equipment to be controlled, the processor can predict damage to the piece of equipment. An example of the additional operating parameter can be the electric current applied to the motor of a disconnect switch. A higher current required to open or close switch is symptomatic of tear and wears. 
         [0049]    At least one additional sensor is required to monitor the additional operating parameter. This sensor communicates the value of the additional operating parameter to the processor through the input/output unit and the isolation unit. For a given value of the operating parameter, a threshold value of the additional operating parameter is stored in the memory. The processor compares the value of the additional operating parameter monitored by the additional sensor to the threshold value stored in the memory. If the monitored value exceeds the threshold value, the processor predicts a damage to the piece of equipment and activates an alarm signal indicating that maintenance or replacement of the piece of equipment is required. 
         [0050]    According to an embodiment, the control module controls a disconnect switch and the processor analyses the evolution in time of the current applied to the motor enabling the movement of the arm of a disconnect switch. In this case, an ampere meter monitors the current applied to the motor and transmits the current value to the processor. Because of EMIs in the electrical substation, the current applied to the motor of the arm can varied and affect the good functioning of the disconnect switch. The processor analyses the monitored value of the current and takes decisions.  FIG. 3  illustrates the current applied to the motor as a function of the location of the arm. Line  154  represents the threshold values of the current as a function of the location of the arm. The values of line  154  are stored into the memory of the logical unit. The processor receives from the ampere meter the value of the current applied to the motor and compares them to the threshold values stored in the memory. If the monitored values correspond to line  150 , the processor compares them to the threshold values corresponding to line  154  and concludes that the applied current is not dangerous for the good functioning of the disconnect switch. But if the monitored values correspond to line  152 , the processor notices the applied current is higher than the threshold value. In this case, the processor activates an alarm signal. 
         [0051]    It should also be understood that the logical unit and the processor can control any motor, pump, valve or component having any kind of movement. 
         [0052]    In an embodiment of the logical unit, a heater permits to maintain the temperature of the processor under operating conditions. As a result, the control module can be located inside or outside an electrical substation. Furthermore, the control module is resistant to extreme climatic conditions. 
         [0053]    In an embodiment, the processor also control the temperature and/or the humidity of the control module. Temperature and/or humidity sensors monitor the temperature and/or humidity in the control module and communicate the temperature and/or humidity to the logical unit through the input/output unit and the isolation unit. The processor receives the measured temperature and/or humidity and compares them to threshold values. If the temperature and/or humidity are not within a tolerable range, the processor adjusts the temperature and/or humidity by varying the voltage applied to the heating system and/or air conditioning system and/or humidifier and/or dehumidifier and/or fan in order to bring the temperature and/or humidity within the tolerable range. 
         [0054]    The input/output unit offers a protection, an isolation and a filtration of all of the signals passing through it. These functions are achieved by an electrical circuit and each signal passing through the input/output unit has its own electrical circuit. These signals include the control signals and the command signals. The electrical circuit includes a protection module, a filtration module and an electrical relay therebetween. 
         [0055]      FIG. 4  illustrates an embodiment of the electrical circuit of the input/output unit for a signal entering the control module. The electrical circuit includes a protection module  202 , a filtration module  204  and an electrical relay  206  used as an isolation module therebetween. The protection module protects the control module from surges and the filtration module increases the quality of the entering signal. The electrical relay includes a coil of actuators  208  and contacts  210 . 
         [0056]    It should be understood that any electrical relay known to a person skilled in the art can be used and falls within the scope of the present embodiment. 
         [0057]    It should also be noted that any protection module which protects an electrical circuit from surges and any filter for increasing the quality of an electrical signal can be used and fall within the scope of the present embodiment. 
         [0058]      FIG. 5  illustrates an embodiment of the control module which further comprises a security unit in comparison to the control module illustrated in  FIG. 1 . The security unit is supplied in power by the power unit. The security unit interacts directly with the input/output unit, the isolation unit, the logical unit and the power unit. The security unit detects any wear or malfunction that can occur in the other units of the control module. Only the security unit and the isolation unit are directly connected to the logical unit. 
         [0059]    If a unit is deficient, the security unit communicates the problem to the processor of the logical unit which takes decisions. Alternatively, the security unit activates an alarm and may also disconnect the control module. 
         [0060]    If the logical unit is deficient, the security unit send an alarm signal or disconnect the control module. The alarm signal is sent through the input/output unit. 
         [0061]    In an embodiment, the security module comprises a processor which analyses the functioning of the other units and takes decision whether an alarm signal must be sent or a problem must be reported to the logical unit. Alternatively, the security unit only comprises electronic digital circuits. 
         [0062]    In another embodiment, the security unit can be integrated in the logical unit. In this case, the logical unit is further connected to the input/output unit and to the power unit. The processor of the logical unit also detects any tear or malfunction that can occur in the other units of the control module. The logical unit is directly related to the power unit, the isolation unit and the input/output unit to receive signals indicating their respective performances. If these signals go above or below threshold values stored in the memory, the logical unit may send an alarm signal and disconnect the control module. 
         [0063]    The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.