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 
     This is the first application filed for the present invention. 
     TECHNICAL FIELD 
     The present invention relates to the field of the supervision, control and protection of a high voltage electrical substation. 
     BACKGROUND OF THE INVENTION 
     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). 
     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 
     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. 
     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. 
     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. 
     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 
       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: 
         FIG. 1  is a block diagram of an embodiment of the control module comprising four units; 
         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; 
         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; 
         FIG. 3  is a graph of the current as a function of location, in accordance with an embodiment of the present invention; 
         FIG. 4  illustrates an embodiment of the electrical circuit of the input/output unit for a signal entering the control module; and 
         FIG. 5  is a block diagram of an embodiment of the control module comprising five units. 
     
    
    
     It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
     DETAILED DESCRIPTION 
     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. 
     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. 
     According to an embodiment of the control module, the control module is protected from voltage surges of about 5000 V. 
     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. 
     The control module can communicate with its external environment which may include other control modules, operators, computers, sensors, pieces of equipments, etc. 
     In an embodiment, the control module  10  comprises 4 units: a power unit  12 , a logical unit  14 , an input/output unit  16 , and an isolation unit  18 , as illustrated in  FIG. 1 . The power unit  12  receives the power supply external to the control module  10  and supplies power to the other units  16  and  18 , except the logical unit  14  which is supplied directly by the external power supply  20 . This unit  12  also supplies power to the switch  22  to be controlled by the control module  10 . 
     In an embodiment, the power unit  12  comprises a power driver  24  and a filtering and isolation sub-unit  26 . The power driver  24  is supplied by the external power supply  20  and supplies power to the switch  22  to be controlled, the isolation unit  18 , and the input/output unit  16 through the isolation and filtering sub-unit  26 . The isolation ( 26   a ) and filtering ( 26   b ) realized by the filtering and isolation sub-unit  26  can be obtained using any technique known to a person skilled in the art. 
     In an embodiment of the control module  10 , the power unit  12  and the logical unit  14  are supplied by an AC current and the power unit  12  generates AC currents to supply the different elements  22  to be controlled and the other units  16  and  18  of the control module  10 . 
     In another embodiment, the power unit  12  and the logical unit  14  are supplied by a DC current and the power unit  12  generates DC currents to supply the different elements  22  to be controlled and the other units  16  and  18  of the control module  10 . One skilled in the art would appreciate that the control module  10  can be supplied by an electrical generator. 
     Referring to  FIG. 1 , the input/output unit  16  represents the interface between the control module  10  and the external environment. In an embodiment, the inputs received by the input/output unit  16  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  28 . For example, the signals coming from the operator can be signals ordering the control module  10  to open or close the switch  22  or signals asking information about the control module  10  or the switch  22 . 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  28  indicate the performances of the piece of equipment  22  to be controlled. For example, the performances can include a pressure, a position or a current intensity. 
     In an embodiment, the signals coming from the sensors  28  go directly to the isolation unit  18  without passing through the input/output unit  16 . 
     The input/output unit  16  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  10  or the switch  22 . Furthermore, the input/output unit  16  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. 
     The logical unit  14  analyses the control signals coming from the sensors  28 , 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  22  to be controlled has to be adjusted or not and sends signals. The signals sent by the logical unit  14  include communication signals internal to the control module  10  and signals directed to the external environment. Signals indicating a voltage to be applied to the switch  22  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  14  communicates to the power unit  12  through the isolation unit  18  the voltage that has to be applied. 
     In an embodiment, the logical unit  14  can also communicate with an external computer  30  and the communication signal passes through the isolation unit  18  before reaching or after leaving the logical unit  14 . 
     In an embodiment, the processor can store about 5 measurements per second during a long period of time. 
     Referring to  FIG. 1 , the isolation unit  18  isolates the logical unit from the power unit  12  and the input/output unit  16 . All signals entering or exiting the logical unit  14  pass by the isolation unit  18 . The isolation unit  18  ensures the security of the logical unit  14  against EMIs and/or RFIs. 
     The isolation unit  18  which isolates the logical unit  14  from the remaining of the control module  10  can be of any kind known by a person skilled in the art. The isolation ( 18   a ) offered by this module  18  can be optical, mechanical and/or galvanic. 
     According to an embodiment, the control module  10  can receive numerical or analog signals. 
     In an embodiment, the control module  10  receives current signals in the range of 4-20 mA and protects them. 
     In an embodiment, the control module  10  further comprises sensors  30  which monitor its environmental conditions of operation such as the temperature and the humidity. Additionally, the control module  10  can adjust the temperature and/or the humidity of the cage comprising the control module  10 . In this case, the sensors  30  communicate with the logical unit  14  through the isolation unit  18 . The logical unit  14  takes decisions to whether or not the temperature and/or the humidity have to be adjusted. If so, the logical unit  14  communicates the voltage to be applied to the heating system and/or air conditioning system and/or humidifier and/or dehumidifier and/or fan  32  to the power unit  12  through the isolation unit  18 . The sensors  30  can be located anywhere in the control module  10 . For example, the sensors  30  can be placed in the power unit  12  and, in this case, the signals sent by the sensors  30  to the processor passes through the isolation and filtering subunit  26  before reaching the isolation unit  18 . 
     In an embodiment, the power unit  12  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. 
     In an embodiment, the operational ranges of the control module  10  are from 90 to 250 V under AC conditions and from 80 to 160 V under DC conditions. 
     The logical unit  10  comprises a processor which analyses the received data coming from sensors  18 . These sensors  28  monitor an operating parameter and the performances of the piece of equipment  22  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  22 . For example, if the piece of equipment  22  is a disconnect switch controlled by a motor, the logical module  14  will decide the voltage that has to be applied to the motor after receiving the order to open the disconnect switch. 
     When the processor receives the order to vary an operating parameter of the piece of equipment  22  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  12  through the isolation unit  18 . The power unit  12  applies the voltage to the piece of equipment  22 . The sensor  28  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  12  which applies it to the piece of equipment  22 . 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  12 . These steps are repeated until the task has been completed. These steps give a plurality of speeds to the opening or closing of the switch  22  and the speed depends on the type of switch being operated. 
     According to an embodiment, the location of an arm of a motorized disconnect switch is controlled by the control module  10 . A sensor  28  indicates the location of the arm to the logical unit  14 . The control module  10  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  12  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  12  which applies it to the motor of the disconnect switch. These steps are repeated until the disconnect switch is completely open. These steps give a plurality of speeds to the arm and the speed depends on the position of the arm, whether it is opening or closing. 
       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  12 . 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. 
       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. 
       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  12 . 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. 
       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. 
       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.    
     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. 
     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  22  to be controlled, the processor can predict damage to the piece of equipment  22 . 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. 
     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  16  and the isolation unit  18 . 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  22  and activates an alarm signal indicating that maintenance or replacement of the piece of equipment  22  is required. 
     According to an embodiment, the control module  10  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. 
     It should also be understood that the logical unit  14  and the processor can control any motor, pump, valve or component having any kind of movement. 
     In an embodiment of the logical unit  14 , a heater permits to maintain the temperature of the processor under operating conditions. As a result, the control module  10  can be located inside or outside an electrical substation. Furthermore, the control module  10  is resistant to extreme climatic conditions. 
     In an embodiment, the processor also control the temperature and/or the humidity of the control module  10 . 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. 
     The input/output unit  16  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  16   a . These signals include the control signals and the command signals. The electrical circuit  16   a  includes a protection module, a filtration module and an electrical relay therebetween. 
       FIG. 4  illustrates an embodiment of the electrical circuit  16   a  of the input/output unit  16  for a signal entering the control module. The electrical circuit  16   a  includes a protection module  202 , a filtration module  204  and an electrical relay  206  used as an isolation module therebetween. The protection module  202  protects the control module from surges and the filtration module  204  increases the quality of the entering signal. The electrical relay  206  includes a coil of actuators  208  and contacts  210 . 
     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. 
     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. 
       FIG. 5  illustrates an embodiment of the control module  300  which further comprises a security unit  302  in comparison to the control module  10  illustrated in  FIG. 1 . The security unit  302  is supplied in power by the power unit  12 . The security unit  12  interacts directly with the input/output unit  16 , the isolation unit  18 , the logical unit  14 , and the power unit  12 . The security unit  302  detects any wear or malfunction that can occur in the other units  12 ,  14 ,  16 , and  18  of the control module  300 . Only the security unit  302  and the isolation unit  18  are directly connected to the logical unit  14 . 
     If a unit  12 ,  14 ,  16 , or  18  is deficient, the security unit  302  communicates the problem to the processor of the logical unit  14  which takes decisions. Alternatively, the security unit  302  activates an alarm and may also disconnect the control module  300 . 
     If the logical unit  14  is deficient, the security unit  302  sends an alarm signal or disconnect the control module  300 . The alarm signal is sent through the input/output unit  16 . 
     In an embodiment, the security module  302  comprises a processor which analyses the functioning of the other units  12 ,  14 ,  16 , and  18  and takes decision whether an alarm signal must be sent or a problem must be reported to the logical unit  14 . Alternatively, the security unit  302  only comprises electronic digital circuits. 
     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. 
     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.