WO2016199272A1 - 地絡過電圧継電装置 - Google Patents
地絡過電圧継電装置 Download PDFInfo
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- WO2016199272A1 WO2016199272A1 PCT/JP2015/066877 JP2015066877W WO2016199272A1 WO 2016199272 A1 WO2016199272 A1 WO 2016199272A1 JP 2015066877 W JP2015066877 W JP 2015066877W WO 2016199272 A1 WO2016199272 A1 WO 2016199272A1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/34—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system
- H02H3/353—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system involving comparison of phase voltages
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
- H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
- H02H3/165—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems for three-phase systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H1/00—Details of emergency protective circuit arrangements
- H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/34—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/083—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for three-phase systems
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
- H02H3/30—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel
- H02H3/302—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus using pilot wires or other signalling channel involving phase comparison
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/38—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to both voltage and current; responsive to phase angle between voltage and current
Definitions
- This disclosure relates to a ground fault overvoltage relay device.
- VT Voltage Transformer
- a fuse is connected to the secondary circuit of the instrument transformer, thereby protecting the instrument transformer from an overcurrent caused by a short circuit failure of the secondary circuit.
- the ground fault overvoltage relay device may erroneously output a break command to a circuit breaker or the like by erroneously determining that a ground fault has been detected. For this reason, a technique for preventing erroneous determination due to secondary circuit disconnection of an instrument transformer is disclosed.
- Patent Document 1 takes a phase voltage from a secondary circuit of an instrument transformer connected to an electric power system, and detects a ground fault by the magnitude of a zero-phase voltage by combining each phase voltage.
- a ground fault overvoltage relay is disclosed.
- the ground fault overvoltage relay includes a first determination unit that detects that at least two phases of the line voltage obtained from each phase voltage are below a predetermined value, and a minimum value of the line voltage and a minimum value of the phase voltage.
- a second determination unit that detects that the ratio is equal to or less than a predetermined value; and a lock unit that locks the ground fault detection output when the first or second determination unit has a detection output.
- a secondary or tertiary circuit of an instrument transformer that inputs a voltage to a ground fault overvoltage relay device is provided with a limiting resistor for limiting a zero-phase current in the event of a ground fault.
- the technique of Patent Document 1 does not consider the case where this limiting resistance is not disconnected or connected for some reason.
- the ground fault overvoltage relay device according to Patent Document 1 is the 2 of the above-described instrument transformer due to an unexpected voltage relationship at the time of a one-phase ground fault. There is a possibility that the next circuit disconnection is erroneously detected.
- the present disclosure has been made in view of the above-described problems, and an object in one aspect is to realize high-sensitivity ground fault detection and to prevent malfunctions and malfunctions due to an abnormality in an instrument transformer. It is an object of the present invention to provide a ground fault overvoltage relay device that can be prevented more accurately.
- An earth fault overvoltage relay device includes an input unit that receives an input of a voltage of a power system detected by an instrument transformer, and a ground fault detection that detects a ground fault based on a zero-phase voltage of the power system.
- a first condition for determining whether or not a first condition that at least two of the line voltages between the two phases calculated based on each phase voltage of the power supply system and the power system are equal to or less than a first threshold value is satisfied.
- a second determination unit that determines whether or not a second condition that a ratio between a minimum value of the line voltage between the two phases and a minimum value of the phase voltages is equal to or less than a second threshold is satisfied.
- a third determination unit that determines whether or not the third condition that the zero-phase voltage is greater than the third threshold is satisfied, and if the first condition is satisfied, or the second condition is satisfied and A lock unit that locks the detection output of the ground fault detection unit when the third condition is not satisfied.
- a ground fault overvoltage relay device includes an input unit that receives an input of a power system voltage detected by an instrument transformer, and a ground fault that detects a ground fault based on a zero-phase voltage of the power system.
- a first unit for determining whether or not a first condition that at least two of the line voltages between the two phases calculated based on each phase voltage of the detection unit and the power system are equal to or less than a first threshold is satisfied.
- a second determination for determining whether or not a second condition that a ratio between the minimum value of the line voltage between each two phases and the minimum value of each phase voltage is equal to or less than a second threshold is satisfied.
- a third determination unit that determines whether or not the third condition that the maximum value of each phase voltage is greater than the third threshold is satisfied, and the second condition is satisfied, or the second A lock unit that locks the detection output of the ground fault detection unit when the condition is satisfied and the third condition is not satisfied.
- FIG. 3 is a circuit obtained by rewriting the equivalent circuit shown in FIG. It is a vector diagram of a symmetrical coordinate component when a limiting resistor is not connected. It is a vector diagram of a phase voltage and a zero-phase voltage when a limiting resistor is not connected. It is a vector diagram of a symmetrical coordinate component when a limiting resistor is connected. It is a vector diagram of a phase voltage and a zero phase voltage when a limiting resistor is connected.
- FIG. 1 is a block diagram showing a functional configuration of an arithmetic processing unit according to the first embodiment.
- FIG. It is a figure for demonstrating the existence area
- FIG. 11 is a block diagram showing a functional configuration of an arithmetic processing unit according to the second embodiment.
- FIG. 11 is a block diagram showing a functional configuration of an arithmetic processing unit according to a third embodiment. It is a figure for demonstrating the structure of the determination control part according to Embodiment 3.
- FIG. It is a figure for demonstrating the detection system of a zero phase voltage.
- FIG. 1 is a diagram showing an electric power system to which a ground fault overvoltage relay device according to the first embodiment is applied.
- a transformer 2 is connected between a load (not shown) which is a consumer such as a home, a building, or a factory, and a system power source 7. Transform to low voltage power available to customers.
- a load not shown
- transformer 2 has a Y-connected primary winding and secondary winding, and a ⁇ -connected tertiary winding.
- the transmission line L is a three-phase (a-phase, b-phase, c-phase) power system line, and receives power supply through the tertiary winding of the transformer 2.
- loads such as homes, buildings, and factories are not connected to the transmission line L (that is, the transmission line L is an unloaded system).
- the neutral point grounding system of the transmission line L is a high resistance grounding system or a non-grounding system.
- the instrument transformer 4 is connected to the transmission line L, detects each phase voltage of the transmission line L, and outputs it to the ground fault overvoltage relay device 3. Specifically, the phase voltages Va, Vb, and Vc of the a-phase, b-phase, and c-phase of the transmission line L are output from the secondary circuit side of the instrument transformer 4 to the ground fault overvoltage relay device 3. . Note that fuses fa, fb, and fc are connected to the secondary circuit of the instrument transformer 4 for each phase.
- the ground fault overvoltage relay device 3 performs an operation necessary for protecting the electric power system such as a relay operation using the taken-in system electric quantity (voltage), and detects the occurrence of the system fault.
- the ground fault overvoltage relay device 3 is a digital protective relay device for protecting the transmission line L.
- FIG. 1 shows an example in which the ground fault overvoltage relay device 3 is connected to the secondary circuit of the instrument transformer 4.
- the “ground fault overvoltage relay device according to the related art” corresponds to the ground fault overvoltage relay device described in Japanese Patent Laid-Open No. 2-46128 (Patent Document 1).
- the impedance of the power system in a state where no load is connected (no load state) like the above-described transmission line L is dominated by the capacitance between the transmission line and the ground.
- the problem of the ground fault overvoltage relay device according to the related art when a one-phase ground fault accident (here, it is assumed that it is an a-phase ground fault accident) occurs in such a transmission line will be described in detail.
- FIG. 2 is a diagram showing an equivalent circuit at the time of a one-phase ground fault by the symmetric coordinate method.
- FIG. 3 is a circuit obtained by rewriting the equivalent circuit shown in FIG. 2 for ease of explanation.
- E, Z1, Z2, C, R, and r are the power supply voltage, the positive phase impedance, the negative phase impedance (line impedance), the capacitance between the transmission line and the ground, and the limit, respectively. Indicates resistance and fault resistance.
- V1, V2, V0, and I0 represent a positive phase voltage, a negative phase voltage, a zero phase voltage, and a zero phase current, respectively.
- the limiting resistor R is usually a resistor connected to the secondary circuit or the tertiary circuit of the instrument transformer 4 for limiting the zero-phase current in the event of a ground fault.
- Vz1 and Vz2 indicate voltages across Z1 and Z2, respectively.
- FIG. 4 is a vector diagram of the symmetric coordinate component when the limiting resistor is not connected.
- the vector diagram as shown in FIG. 4 is obtained for the following reason. Specifically, since an unloaded power system is assumed, the capacitance C is dominant in the load of the zero-phase circuit. Therefore, the zero-phase current I0 has a leading phase with respect to the power supply voltage E. In the example of FIG. 4, the zero-phase current I0 is set to a phase advance of ⁇ 90 °.
- the positive phase impedance Z1 and the negative phase impedance Z2 can be regarded as almost inductors, the voltages Vz1 and Vz2 at both ends of the positive phase impedance Z1 and the negative phase impedance Z2 are advanced with respect to the zero phase current I0. (For example, about 90 °).
- the vectors of the both-end voltages Vz1 and Vz2 are advanced by about 180 ° with respect to the power supply voltage E. Then, the zero-phase voltage V0 can be obtained by combining the power supply voltage E and the both-end voltages Vz1 and Vz2. Therefore, as shown in FIG. 4, the relationship of power supply voltage E ⁇ zero phase voltage V0 is established. This is the same principle as the ferrant effect (a phenomenon in which the receiving end voltage becomes higher than the transmitting end voltage).
- the terminal side of the vector of the zero-phase voltage V0 means a neutral potential
- the relationship between the zero-phase voltage V0 and the phase voltages Va, Vb, and Vc is expressed as shown in FIG. .
- FIG. 5 is a vector diagram of the phase voltage and the zero-phase voltage when the limiting resistor is not connected.
- each phase voltage Va, Vb, and Vc is higher than each phase voltage in a healthy state due to the fluctuation of the neutral point potential (change from the point N to the point N1) due to the change of the zero-phase voltage V0. You can see that it is getting bigger.
- K2 a predetermined value
- the minimum phase voltage is the a-phase voltage Va.
- the a-phase voltage Va that is, the denominator on the left side of the equation (1)
- the equation (1) is easily established.
- the ground fault overvoltage relay device may erroneously determine that the instrument transformer 4 is abnormal and malfunction (lock the ground fault output) in spite of the one-phase ground fault. .
- the line voltages Vab, Vbc, Vca normally maintain the rated line voltage.
- the transmission line linked to the transformer 2 for example, the transmission line on the primary winding side of the transformer 2 in FIG. 1
- Inrush current flows through the transformer 2. Due to this inrush current, the balance of the voltages of the respective phases is lost, and the minimum line voltage (that is, the numerator on the left side of Equation (1)) becomes small. Therefore, the formula (1) is more likely to be established, and the ground fault overvoltage relay device according to the related technology is more likely to malfunction.
- FIG. 6 is a vector diagram of a symmetric coordinate component when a limiting resistor is connected.
- the vector diagram as shown in FIG. 6 is obtained for the following reason. Specifically, when the limiting resistor R is connected even in an unloaded power system, the load of the zero-phase circuit is resistive (the limiting resistor R is dominant). Therefore, the zero-phase current I0 has a leading phase with respect to the power supply voltage E, but does not have the leading phase as shown in FIG. Specifically, the phase ⁇ shown in FIG. 6 is smaller than the phase ⁇ shown in FIG.
- the relationship between the power supply voltage E and the zero-phase voltage V0 is expressed as shown in FIG. 4 and 6, the zero-phase voltage V0 (see FIG. 6) when the limiting resistor R is connected is larger than the zero-phase voltage V0 (see FIG. 4) when the limiting resistor R is not connected. Get smaller.
- the relationship between the zero-phase voltage V0 and the phase voltages Va, Vb, Vc is expressed as shown in FIG.
- FIG. 7 is a vector diagram of the phase voltage and the zero-phase voltage when the limiting resistor is connected.
- the neutral point potential fluctuates due to the change of the zero-phase voltage V0 (fluctuation from the point N to the point N2), but is more neutral than when the limiting resistor is not connected (see FIG. 5). The fluctuation of the point potential is small.
- the minimum phase voltage is the a-phase voltage Va as in FIG.
- the a-phase voltage Va in FIG. 7 is smaller than the a-phase voltage Va in FIG. Therefore, the a-phase voltage Va (that is, the denominator on the left side of the equation (1)) is smaller than that when the power transmission line L is normal, so the equation (1) does not hold. That is, when the limiting resistor R is connected, the ground fault overvoltage relay device according to the related technology erroneously determines a one-phase ground fault as an abnormality of the instrument transformer 4 and causes malfunction (ground fault). The output is not locked.
- FIGS. 2 to 7 an unloaded power system is assumed.
- the operation of the ground fault overvoltage relay device according to the related art when an inductive reactance load is connected to the power system will be examined just in case. It is assumed that the limiting resistor R is not connected to the secondary circuit or the tertiary circuit of the instrument transformer 4.
- the relationship between the power supply voltage E and the zero-phase voltage V0 in such a case is represented by a vector, it is shown as in FIG.
- FIG. 8 is a vector diagram of symmetric coordinate components when an inductive reactance load is connected to the power system.
- the vector diagram as shown in FIG. 8 is obtained for the following reason. Specifically, in an electric power system in which an inductive reactance load is dominant, the zero-phase current I0 is delayed with respect to the power supply voltage E. Further, the positive-phase impedance Z1 and the negative-phase impedance Z2 can be regarded as inductances as in the case of FIG. 4, so that the both-end voltages Vz1 and Vz2 are advanced with respect to the zero-phase current I0. Therefore, the relationship between the power supply voltage E and the zero-phase voltage V0 is expressed as shown in FIG.
- the zero-phase voltage V0 (see FIG. 8) is the zero-phase voltage when the limiting resistor R is not connected. It becomes smaller than V0 (see FIG. 4).
- the relationship between the zero-phase voltage V0 and the phase voltages Va, Vb, and Vc is expressed as shown in FIG.
- FIG. 9 is a vector diagram of phase voltage and zero phase voltage when an inductive reactance load is connected.
- the neutral point potential fluctuates due to the change of the zero-phase voltage V0 (fluctuation from the point N to the point N3), but is more intermediate than when the limiting resistor R is not connected (see FIG. 5).
- the variation in sex point potential is small. Therefore, as in the case of FIG. 7, the a-phase voltage Va (that is, the denominator on the left side of the equation (1)) is smaller than that when the transmission line L is normal, so the equation (1) does not hold.
- the ground fault overvoltage relay device As described above, the ground fault overvoltage relay device according to the related art is when the limiting resistor is connected to the secondary circuit or the tertiary circuit of the instrument transformer 4 or when the load is connected to the power system. Works fine. However, the ground fault overvoltage relay device may malfunction if a load is not connected to the power system and a limiting resistor is not connected to the secondary circuit or the tertiary circuit of the instrument transformer 4. High nature.
- the ground fault overvoltage relay device 3 is a one-phase ground fault accident by adding a configuration described later to the ground fault over voltage relay device according to the related technology. Is detected properly.
- FIG. 10 is a diagram showing a hardware configuration of ground fault overvoltage relay device 3 according to the first embodiment.
- ground fault overvoltage relay device 3 includes an auxiliary transformer 10, an AD (Analog to Digital) conversion unit 20, and an arithmetic processing unit 30.
- AD Analog to Digital
- the auxiliary transformer 10 takes in the grid electricity from the instrument transformer 4, converts it into a smaller electricity, and outputs it.
- the AD converter 20 takes in the grid electricity quantity (analog quantity) output from the auxiliary transformer 10 and converts it into digital data.
- the AD conversion unit 20 includes a filter 21, a sample hold (SH) circuit 24, a multiplexer 26, and an AD converter 27.
- the filter 21 is an analog filter and removes a high frequency noise component from the waveform signal of the voltage output from the auxiliary transformer 10.
- the output of the filter 21 is input to the SH circuit 24.
- the SH circuit 24 samples the waveform signal of the voltage output from the filter 21 at a predetermined sampling period.
- the multiplexer 26 sequentially switches the waveform signal input from the SH circuit 24 in time series based on the timing signal input from the arithmetic processing unit 30 and inputs the waveform signal to the AD converter 27.
- the AD converter 27 converts the waveform signal input from the multiplexer 26 from analog data to digital data.
- the AD converter 27 outputs the digitally converted waveform signal (digital data) to the arithmetic processing unit 30.
- the arithmetic processing unit 30 is mainly composed of a microcomputer. Specifically, the arithmetic processing unit 30 includes a CPU (Central Processing Unit) 32, a ROM (Read Only Memory) 33, a RAM 34 (Random Access Memory), a DO (digital output) circuit 36, and a DI (digital input). ) Circuit 37. These are connected by a bus 31.
- a CPU Central Processing Unit
- ROM Read Only Memory
- RAM 34 Random Access Memory
- DO digital output circuit
- DI digital input
- the CPU 32 controls the operation of the ground fault overvoltage relay device 3 as a control unit by reading and executing a program stored in the ROM 33 in advance.
- the CPU 32 is, for example, a microprocessor.
- the hardware may be an FPGA (Field Programmable Gate Array) other than the CPU, an ASIC (Application Specific Integrated Circuit), or a circuit having other arithmetic functions.
- the CPU 32 captures digital data from the AD conversion unit 20 via the bus 31.
- the CPU 32 executes a relay operation using the captured digital data in accordance with a program stored in the ROM 33.
- the CPU 32 determines whether or not there is a failure in the protection section (area to be protected) based on the relay calculation result.
- the CPU 32 detects a failure (for example, when the calculated value exceeds the set value)
- the CPU 32 uses the DO circuit 36 to connect the failure section to the power system (transmission line L).
- a break command is output to a connected breaker (not shown).
- the DI circuit 37 receives, for example, a digital input signal which is a signal indicating circuit breaker switching information.
- FIG. 11 is a block diagram showing a functional configuration of arithmetic processing unit 30 according to the first embodiment.
- arithmetic processing unit 30 includes a first determination unit 100, a second determination unit 200, a third determination unit 300, a lock unit 400, and a ground fault detection unit 500. .
- the ground fault detection unit 500 detects a ground fault based on the zero-phase voltage of the transmission line L.
- ground fault detection unit 500 includes a determination circuit 501 and a logic gate 502.
- the determination circuit 501 is a so-called ground fault overvoltage relay element.
- the determination circuit 501 determines that
- the determination circuit 501 outputs the output value “1” to the logic gate 502, and
- the logic gate 502 performs an AND operation on the output value of the determination circuit 501 and a value obtained by inverting the logic level of the output of the logic gate 402 of the lock unit 400. Specifically, when the output of the determination circuit 501 is not blocked by the output of the logic gate 402 (lock command output described later) (the output is not hindered), the detection output of the ground fault detection unit 500 The interruption command is output to the circuit breaker. On the other hand, when the output of the determination circuit 501 is blocked by the output of the logic gate 402, the interrupt command is not output to the circuit breaker.
- the first determination unit 100 and the second determination unit 200 are provided to determine abnormality of the instrument transformer 4 and have a ground fault overvoltage relay device according to related technology.
- first, the reason why the first determination unit 100 and the second determination unit 200 are provided will be described.
- the a-phase voltage Va that is a disconnected phase is from the secondary cable of the phase voltages Vb and Vc that are healthy phases.
- the region where Va (vector) exists is generally considered to be within the range of the region 700 shown in FIG.
- FIG. 12 is a diagram for explaining a region where the a-phase voltage Va is present when the instrument transformer 4 is disconnected from the a-phase.
- FIG. 12 at the time of a phase disconnection of instrument transformer 4, if there is no induced voltage from b phase or c phase which is another healthy phase due to a phase disconnection, it becomes 0V. However, when the induced voltage from the b phase or the c phase is superimposed on the a phase, the a phase voltage Va is generated. Therefore, the region where the a-phase voltage Va of the disconnection phase exists is within the range of the region 700 in FIG.
- phase voltages Va, Vb, Vc input to the ground fault overvoltage relay device 3 are as shown in FIGS. 13 to 16 according to the state of the transmission line L. It is expressed in
- FIG. 13 is a vector diagram of each phase voltage when the transmission line L is normal.
- FIG. 14 is a vector diagram of each phase voltage when a one-phase ground fault occurs in the a phase of the transmission line L.
- FIG. 15 is a vector diagram of each phase voltage when a two-phase ground fault (ignoring arc resistance) occurs in the ab phase of the transmission line L.
- FIG. 16 is a vector diagram of each phase voltage when a two-phase ground fault (considering arc resistance) occurs in the ab phase of the transmission line L.
- the first determination unit 100 that determines whether or not at least two of the line voltages between the two phases are equal to or less than the threshold value K1, the minimum value of the line voltages between the two phases and the minimum value of the phase voltages.
- the arithmetic processing unit 30 is provided with a second determination unit 200 that determines whether or not the ratio is less than or equal to the threshold value ⁇ .
- the first determination unit 100 includes determination circuits 101, 102, 103 and logic gates 104, 105, 106, 107.
- the determination circuits 101, 102, and 103 determine whether or not the line voltages Vab, Vbc, and Vca are less than or equal to the threshold value K1, respectively. Each determination circuit outputs “1” when it is determined that the corresponding line voltage is equal to or lower than the threshold value K1, and outputs “0” when it is determined that the line voltage is greater than the threshold value K1. .
- the threshold value K1 a value obtained by comparing the constant A with a value obtained by multiplying the maximum value (absolute value) of the line voltages Vab, Vbc, Vca by a coefficient ⁇ ( ⁇ ⁇ 1) is adopted.
- the logic gate 104 performs AND operation on the output values of the determination circuits 101 and 102, the logic gate 105 performs AND operation on the output values of the determination circuits 102 and 103, and the logic gate 106 determines the determination circuit 103. , 101 are ANDed. Output values of the logic gates 104 to 106 are input to the logic gate 107. Logic gate 107 performs an OR operation on the output values of logic gates 104-106. The output value of the logic gate 107 is input to the logic gate 402.
- the a-phase voltage Va is generally considered to be within the range 700 of FIG.
- the line voltages Vab and Vca are smaller than the line voltage Vbc.
- the value obtained by multiplying the line voltages Vab, Vbc, Vca by the coefficient ⁇ corresponds to the minimum value of the line voltage measured when the instrument transformer 4 is normal, and at least two line voltages are larger than this value. Is small, it can be determined that the instrument transformer 4 is abnormal.
- the constant A is a fixed value for detecting a two-wire disconnection of the instrument transformer 4.
- Such a first determination unit 100 may be configured to be able to determine whether the condition X1 is satisfied, and may be realized by a configuration (determination circuit, logic gate) other than the above.
- the second determination unit 200 includes determination circuits 201 and 202.
- the determination circuit 201 determines whether or not the ratio between the minimum line voltage and the minimum phase voltage (the ratio of the minimum line voltage to the minimum phase voltage) is equal to or less than the threshold ⁇ (> 1). That is, the determination circuit 201 determines whether or not the above formula (1) is established. Thereby, when the condition X2 that the ratio of the minimum values of the line voltages Vab, Vbc, Vca between the two phases and the minimum values of the phase voltages Va, Vb, Vc is equal to or less than the threshold value ⁇ is satisfied, An output value “1” is output from the determination circuit 201 to a logic gate 401 described later. If not, an output value “0” is output to the logic gate 401.
- the determination circuit 202 determines whether or not the minimum phase voltage is a constant K2 or more. That is, the determination circuit 202 determines whether or not the above equation (2) is satisfied.
- the determination circuit 202 outputs “1” to the logic gate 401 when determining that the minimum phase voltage is equal to or greater than the constant K2, and outputs “0” otherwise.
- the a-phase voltage Va is generally considered to be within the range 700 of FIG. 12 when the instrument transformer 4 is disconnected in the a-phase.
- the ratio of the minimum values of the line voltages Vab, Vbc, Vca to the a-phase voltage Va, b-phase voltage Vb, or c-phase voltage Vc can take a value near 1.
- the ratio between the minimum value of each phase voltage Va, Vb, Vc and the minimum value of the line voltages Vab, Vbc, Vca is 3 when the transmission line L is normal and abnormal. It is clear that it becomes 1/2 or more. Therefore, when this ratio is equal to or less than a threshold value ⁇ (for example, 1.3), it can be determined that the instrument transformer 4 is abnormal.
- a threshold value ⁇ for example, 1.3
- the coefficient ⁇ does not malfunction when there is a one-phase ground fault, and the false lock area decreases when there is a two-phase ground fault, and the detection area is as small as possible for an abnormality in the instrument transformer 4. It is determined to be wide. Therefore, the coefficient ⁇ is set to 1.3, for example.
- the determination circuit 202 prevents erroneous determination of the determination circuit 201 by determining whether or not the minimum values of the phase voltages Va, Vb, and Vc are equal to or greater than the constant K2.
- the constant K2 is set to 20V, for example.
- the third determination unit 300 determines whether or not the condition X3 that the zero-phase voltage is larger than the third threshold is satisfied.
- the third determination unit 300 erroneously determines that the instrument transformer 4 is abnormal by the second determination unit 200 in spite of the one-phase ground fault, and malfunctions (locks the ground fault output). Provided to prevent the possibility.
- K3 (phase voltage under normal conditions) ⁇ 3 1/2 ⁇ ⁇ (4)
- the third determination unit 300 determines whether or not the expression (4) is satisfied (that is, determines the condition X3).
- the logic gate 401 is set to “1”. Is output, otherwise “0” is output.
- the lock unit 400 When the condition X1 by the first determination unit 100 is satisfied, or when the condition X2 by the second determination unit 200 is satisfied and the condition X3 by the third determination unit 300 is not satisfied, the lock unit 400 The detection output by the detection unit 500 is locked.
- the lock unit 400 includes logic gates 401 and 402.
- the logic gate 401 performs an AND operation on the output value of the second determination unit 200 and the value obtained by inverting the logic level of the output of the third determination unit 300.
- the output of the second determination unit 200 is blocked by the output of the third determination unit 300.
- the output of the second determination unit 200 is blocked if the condition X3 by the third determination unit 300 is satisfied. .
- the logic gate 402 performs an OR operation on the output value of the logic gate 107 of the first determination unit 100 and the output value of the logic gate 401. As a result, when “1” is output from the logic gate 107 or “1” is output from the logic gate 401, “1” is output from the logic gate 402 to the logic gate 502 (the lock command is output). ) In this case, as described above, the ground fault detection output of the ground fault detection unit 500 is locked.
- FIG. 17 is a flowchart showing an example of a processing procedure of arithmetic processing unit 30 according to the first embodiment. The following steps are mainly realized by the CPU 32 of the arithmetic processing unit 30 executing a program stored in the ROM 33. Here, for ease of explanation, it is assumed that determination by the determination circuit 202 provided for erroneous determination of the determination circuit 201 is satisfied (formula (2) is satisfied).
- the arithmetic processing unit 30 receives (acquires) input of each phase voltage of the transmission line L detected by the instrument transformer 4 (step S ⁇ b> 10).
- the arithmetic processing unit 30 calculates a zero phase voltage (calculated from the sum of the phase voltages) based on the acquired phase voltages (step S20).
- the arithmetic processing unit 30 determines whether or not the calculated zero-phase voltage is an overvoltage (that is,
- the arithmetic processing unit 30 ends the process. That is, the arithmetic processing unit 30 determines that a ground fault has not been detected. When the zero-phase voltage is an overvoltage (YES in step S30), the arithmetic processing unit 30 determines whether or not at least two of the line voltages between the two phases are equal to or less than the threshold value K1 (condition X1 is satisfied). Whether or not) (step S40).
- the arithmetic processing unit 30 locks the ground fault detection output (step S50). Specifically, the arithmetic processing unit 30 invalidates the output of the ground fault overvoltage relay element so that the interruption command is not output to the circuit breaker.
- the arithmetic processing unit 30 determines whether the ratio between the minimum value of the line voltage between each two phases and the minimum value of each phase voltage is equal to or less than the threshold value ⁇ . It is determined whether or not the condition X2 is satisfied (step S60).
- step S60 If the condition X2 is not satisfied (NO in step S60), the arithmetic processing unit 30 enables (does not lock) the ground fault detection output (step S80). Specifically, the arithmetic processing unit 30 outputs a break command to the circuit breaker as a ground fault detection output of the ground fault overvoltage relay element. If condition X2 is satisfied (YES in step S60), operation processing unit 30 determines whether zero-phase voltage
- step S70 If the condition X3 is satisfied (YES in step S70), the arithmetic processing unit 30 enables the ground fault detection output (step S80) and ends the process. When condition X3 is not satisfied (NO in step S70), arithmetic processing unit 30 locks the ground fault detection output (step S50) and ends the process.
- the abnormality of the instrument transformer and the one-phase ground fault of the power system can be detected separately. Even in such a case, the abnormality of the instrument transformer is not unnecessarily detected at the time of a one-phase ground fault, so that the power system can be appropriately protected by outputting a shut-off command or the like.
- FIG. 18 is a block diagram showing a functional configuration of arithmetic processing unit 30A according to the second embodiment.
- arithmetic processing unit 30 ⁇ / b> A includes a first determination unit 100, a second determination unit 200, a third determination unit 300 ⁇ / b> A, a lock unit 400, and a ground fault detection unit 500.
- the arithmetic processing unit 30A corresponds to the arithmetic processing unit 30 illustrated in FIG. 10, but for the sake of distinction from the first embodiment, an additional code such as “A” is attached for convenience. This is the same in the third embodiment. Since first determination unit 100, second determination unit 200, lock unit 400, and ground fault detection unit 500 in FIG. 18 are the same as those in FIG. 11, detailed description thereof will not be repeated.
- the third determination unit 300A determines whether or not the condition X3a that the maximum value of each phase voltage is larger than the threshold value K4 is satisfied. Thus, the second determination unit 200 prevents the possibility of erroneous operation due to erroneous determination that the instrument transformer 4 is abnormal despite the one-phase ground fault.
- the a-phase voltage Va is generally considered to be within the range 700 of FIG. Therefore, the relationship of the a-phase voltage Va ⁇ healthy phase voltage of the disconnection phase is established.
- the healthy phase voltage is constant regardless of the disconnection of the instrument transformer 4.
- K4 (phase voltage) ⁇ ⁇ (5)
- ⁇ Processing procedure> in the second embodiment is executed when the arithmetic processing unit 30A determines whether or not Expression (5) is satisfied in Step S70 in FIG. Specifically, the arithmetic processing unit 30A locks the ground fault detection output when the formula (5) is not satisfied (step S50 in FIG. 17), and when the formula (5) is satisfied, The fault detection output is validated (step S80 in FIG. 17).
- the configuration of the third determination unit can be selected as appropriate, and the degree of freedom in design is improved.
- FIG. 19 is a block diagram showing a functional configuration of arithmetic processing unit 30B according to the third embodiment.
- arithmetic processing unit 30B includes first determination unit 100, second determination unit 200, third determination unit 300B, lock unit 400B, ground fault detection unit 500, determination And a control unit 600B.
- the 1st determination part 100 in FIG. 19, the 2nd determination part 200, and the ground fault detection part 500 are the same as the thing in FIG. 11, the detailed description is not repeated.
- the inrush current flows to the transformer 2 when the circuit breaker CB is turned on again after a power failure of the transmission line L.
- each phase voltage of the transmission line L also rapidly increases. Therefore, when each phase voltage of the transmission line L rises after a power failure (abruptly increases), it can be considered that the circuit breaker CB is turned on again (inrush current is generated). Therefore, the determination control unit 600B performs the third operation only for a predetermined time after detecting the rising of each phase voltage after a power failure of the transmission line L (that is, a period during which it is easy to erroneously determine that the instrument transformer 4 is abnormal).
- the determination unit 300B is controlled to execute the determination of the condition X3 (or the condition X3a).
- the determination control unit 600B causes the third determination unit 300B to execute the determination of the condition X3.
- FIG. 20 is a diagram for illustrating a configuration of a determination control unit according to the third embodiment.
- determination control unit 600B includes determination circuits 601-603, 621-623, logic gates 604, 624, 641, timer circuits 631, 632, and an output circuit 642.
- Determination circuits 601 to 603 determine whether the phase voltages Va, Vb, and Vc are less than the threshold value K5, respectively. Each determination circuit outputs “1” when it is determined that the corresponding phase voltage is less than the threshold value K5, and outputs “0” otherwise.
- Logic gate 604 performs an AND operation on the output values of determination circuits 601 to 603.
- the threshold value K5 is a value set for detecting a power failure in the power system, and is 5V, for example.
- the timer circuit 631 is a circuit that performs an on-delay operation.
- the timer circuit 631 outputs the output value “1” to the timer circuit 632 when the output value “1” from the logic gate 604 is maintained for the time T1.
- the time T1 is set to a time at which the power transmission line L can be regarded as being out of power, and is, for example, 30 seconds.
- the timer circuit 632 is a circuit that performs an off-delay operation.
- the timer circuit 632 outputs the output value “0” to the logic gate 641 when the output value “0” from the timer circuit 631 is maintained for the time T2.
- the time T2 is, for example, 100 milliseconds.
- Determination circuits 621 to 623 determine whether or not the phase voltages Va, Vb, and Vc are larger than the threshold value K6, respectively. Each determination circuit outputs “1” when it is determined that the corresponding phase voltage is larger than the threshold value K6, and outputs “0” otherwise.
- Logic gate 624 performs an OR operation on the output values of determination circuits 621 to 623.
- the threshold value K6 is a value set for detecting the return of the voltage of the transmission line L, and is, for example, 50V.
- the logic gate 641 performs an AND operation on the output value of the timer circuit 632 and the output value of the logic gate 624.
- the output circuit 642 When receiving the output value “1” from the logic gate 641, the output circuit 642 outputs the output value “1” only for the time T 3.
- the time T3 is set in consideration of the period during which the inrush current flows when the transformer 2 is turned on, and is, for example, 1 minute.
- the output from the timer circuit 631 The value “1” is output.
- the output value “1” is output from the timer circuit 632 and the logic gate 624 for the time T2, and thus the output value “1” is output from the logic gate 641.
- the output value “1” is output from the output circuit 642 for the time T3.
- the determination control unit 600B determines that at least one of the phase voltages is equal to or higher than the threshold value K5 after a power failure of the transmission line L
- the execution instruction (output from the output circuit 642 is output).
- Output value “1”) to the third determination unit 300B.
- the determination control unit 600B instructs to stop the determination when the predetermined time (corresponding to the time T3) has elapsed after the determination of the condition X3 is started (the output value “0 output from the output circuit 642). "Corresponding to”) is sent to the third determination unit 300B.
- the third determination unit 300B starts or stops determining whether or not the condition X3 is satisfied according to control by the determination control unit 600B. Specifically, when the third determination unit 300B receives the execution instruction from the determination control unit 600B (when at least one of the phase voltages becomes equal to or higher than the threshold value K5 after a power failure of the transmission line L), the condition Determination of whether X3 is materialized is started. In addition, when the third determination unit 300B receives the stop instruction from the determination control unit 600B (when a predetermined time has elapsed since the start of the determination as to whether or not the condition X3 is satisfied), The determination is stopped.
- the lock unit 400B When the determination is stopped by the third determination unit 300B, the lock unit 400B has the ground fault detection unit 500 when the condition X1 by the first determination unit 100B or the condition X2 by the second determination unit 200B is satisfied. Locks the detection output by.
- the lock unit 400B is similar to the lock unit 400A when the condition X1 is satisfied, or the condition X2 is satisfied and When the condition X3 is not established, the detection output by the ground fault detection unit 500 is locked.
- the determination control unit 600B may be configured to receive information indicating the insertion of the circuit breaker CB from the circuit breaker CB.
- the ground fault overvoltage relay device 3 and the circuit breaker CB are configured to be communicable.
- the determination control unit 600B according to the modified example determines whether the circuit breaker CB is turned on or opened by receiving a closing signal or an opening signal from the circuit breaker CB.
- the determination control unit 600B sends an execution instruction to execute the determination of the condition X3 to the third determination unit 300B when receiving information indicating the insertion of the circuit breaker CB. Then, the determination control unit 600B sends a stop instruction to stop the determination to the third determination unit 300B when a predetermined time has elapsed after the determination of the condition X3 is started.
- the determination of the condition X3 or the condition X3a is executed only during a period when the possibility that the ground fault overvoltage relay device malfunctions is high. Therefore, the processing load on the apparatus can be reduced.
- the ground fault overvoltage relay apparatus 3 demonstrated the structure which calculates a zero phase voltage based on each phase voltage taken in from the transformer 4 for instruments, it is not restricted to the said structure, For example, It may be configured to detect as shown in FIG.
- FIG. 21 is a diagram for explaining a zero-phase voltage detection method.
- ground fault overvoltage relay device 3 is configured to capture a zero-phase voltage (3V0) detected by connecting the tertiary winding of instrument transformer 4 to an open delta. May be.
- the configuration illustrated as the above-described embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part of the configuration is omitted without departing from the gist of the present invention. It is also possible to change the configuration.
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Abstract
Description
<全体構成>
図1は、実施の形態1に従う地絡過電圧継電装置が適用される電力系統を示す図である。図1を参照して、変圧器2は、家庭やビル、工場などの需要家である負荷(図示しない)と系統電源7との間に接続されており、系統電源7からの高圧電力を、需要家が利用可能な低圧電力に変圧する。本実施の形態では、変圧器2は、Y結線された1次巻線および2次巻線と、Δ結線された3次巻線とを有する場合について説明する。
ここで、本実施の形態の理解のため、まず、関連技術およびその関連技術における課題などについて説明する。なお、「関連技術に従う地絡過電圧継電装置」は、上述の特開平2-46128号公報(特許文献1)の地絡過電圧継電装置に該当する。
最初に、制限抵抗Rが計器用変圧器4の2次回路または3次回路に接続されていない場合について考える。このような場合における図3中の電源電圧Eと零相電圧V0の関係をベクトルで表すと、図4のように示される。
Min(|Va|,|Vb|,|Vc|)≧K2・・・・・・・・・・・・・・(2)
なお、式(2)を用いた判定は、各相電圧が異常な値になっているか否かを判定するため(正常な範囲で式(1)を用いた判定を可能とするため)に行われる。ここでは、式(2)については成立するものとみなす。
次に、制限抵抗Rが計器用変圧器4の2次回路または3次回路に接続されている場合について考える。このような場合における図3中の電源電圧Eと零相電圧V0の関係をベクトルで表すと、図6のように示される。
図2~図7においては、無負荷状態の電力系統を想定していた。ここでは、仮に電力系統に誘導性リアクタンス負荷が接続されている場合の関連技術に従う地絡過電圧継電装置の動作について念のため検討しておく。なお、制限抵抗Rは、計器用変圧器4の2次回路または3次回路に接続されていないものとする。このような場合における電源電圧Eと零相電圧V0の関係をベクトルで表すと、図8のように示される。
上述したように、関連技術に従う地絡過電圧継電装置は、計器用変圧器4の2次回路または3次回路に制限抵抗が接続されている場合、または電力系統に負荷が接続されている場合には、正常に動作する。しかし、当該地絡過電圧継電装置は、電力系統に負荷が接続されておらず、計器用変圧器4の2次回路または3次回路に制限抵抗が接続されていない場合には、誤動作する可能性が高い。
図10は、実施の形態1に従う地絡過電圧継電装置3のハードウェア構成を示す図である。図10を参照して、地絡過電圧継電装置3は、補助変成器10と、AD(Analog to Digital)変換部20と、演算処理部30とを含む。
図11は、実施の形態1に従う演算処理部30の機能構成を示すブロック図である。図11を参照して、演算処理部30は、第1の判定部100と、第2の判定部200と、第3の判定部300と、ロック部400と、地絡検出部500とを含む。
そのため、送電線Lには1相地絡が発生しておらず計器用変圧器4の1相断線のみが発生している場合には、基本的には上記の式(3)が成立する。換言すると、マージンγ(たとえば、1.2)を考慮した以下の式(4)が成立する場合には、計器用変圧器4の異常ではなく送電線Lに地絡事故が発生しているといえる。
線間電圧が110Vである場合には、相電圧は110V/31/2≒63.5Vとなるため、たとえば、K3=132Vに設定される。
図17は、実施の形態1に従う演算処理部30の処理手順の一例を示すフローチャートである。以下のステップは、主に、演算処理部30のCPU32がROM33に格納されたプログラムを実行することにより実現される。なお、ここでは、説明の容易化のため、判定回路201の誤判定用に設けられた判定回路202による判定は成立(式(2)が成立)するものとする。
実施の形態1によると、何らかの原因で計器用変圧器に制限抵抗が接続されていない、あるいは断線している場合であっても、計器用変圧器の異常と電力系統の1相地絡事故とを区別して検出することができる。このような場合であっても、1相地絡事故時に計器用変圧器の異常検出を不要に行なうことがないため、遮断指令を出力するなどにより電力系統を適切に保護することができる。
実施の形態1では、計器用変圧器4の異常(断線)と1相地絡事故とをより精度よく検出するために、零相電圧を用いた第3の判定部300を設ける構成について説明した。実施の形態2では、実施の形態1の第3の判定部300の代わりに、相電圧を用いた第3の判定部を設ける構成について説明する。なお、実施の形態2の<全体構成>および<ハードウェア構成>については、実施の形態1と同じであるため、その詳細な説明は繰り返さない。
線間電圧が110Vである場合には、相電圧は110V/31/2≒63.5Vとなるため、たとえば、K4=76.2Vに設定される。
実施の形態2によると、実施の形態1と同様な利点がある。そのため、第3の判定部の構成を適宜選択することができ、設計上の自由度が向上する。
上述の<関連技術およびその課題>で説明したように、1相地絡事故時において、変圧器2にインラッシュ電流が発生した場合には各相電圧のバランスが崩れ、さらに式(1)が成立しやすくなってしまう。その結果、地絡過電圧継電装置は計器用変圧器4の異常と誤判定して誤不動作する可能性が高くなってしまう。実施の形態3では、このように地絡過電圧継電装置が誤不動作する可能性が高まる期間に、上述した第3の判定部による判定を行なう構成について説明する。なお、実施の形態3の<全体構成>および<ハードウェア構成>については、実施の形態1と同じであるため、その詳細な説明は繰り返さない。
なお、変形例として、判定制御部600Bは、遮断器CBの投入を示す情報を当該遮断器CBから受信する構成であってもよい。この場合、地絡過電圧継電装置3と遮断器CBとは、通信可能に構成されている。たとえば、変形例に従う判定制御部600Bは、遮断器CBからの投入信号または開放信号を受信することにより、遮断器CBの投入または開放を判断する。
実施の形態3によると、地絡過電圧継電装置が誤不動作する可能性が高い期間に限って条件X3または条件X3aの判定が実行される。そのため、装置の処理負荷を軽減することができる。
上述した実施の形態では、地絡過電圧継電装置3は、計器用変圧器4から取り込まれる各相電圧に基づいて零相電圧を算出する構成について説明したが、当該構成に限られず、たとえば、図21に示すように検出する構成であってもよい。
Claims (5)
- 計器用変圧器によって検出された電力系統の電圧の入力を受ける入力部と、
前記電力系統の零相電圧に基づいて地絡を検出する地絡検出部と、
前記電力系統の各相電圧に基づいて算出される各2相間の線間電圧の少なくとも2つが第1の閾値以下であるとの第1条件が成立するか否かを判定する第1の判定部と、
前記各2相間の線間電圧の最小値と前記各相電圧の最小値との比率が第2の閾値以下であるとの第2条件が成立するか否か判定する第2の判定部と、
前記零相電圧が第3の閾値よりも大きいとの第3条件が成立するか否かを判定する第3の判定部と、
前記第1条件が成立した場合、または、前記第2条件が成立かつ前記第3条件が不成立の場合に、前記地絡検出部による検出出力をロックするロック部とを備える、地絡過電圧継電装置。 - 計器用変圧器によって検出された電力系統の電圧の入力を受ける入力部と、
前記電力系統の零相電圧に基づいて地絡を検出する地絡検出部と、
前記電力系統の各相電圧に基づいて算出される各2相間の線間電圧の少なくとも2つが第1の閾値以下であるとの第1条件が成立するか否かを判定する第1の判定部と、
前記各2相間の線間電圧の最小値と前記各相電圧の最小値との比率が第2の閾値以下であるとの第2条件が成立するか否か判定する第2の判定部と、
前記各相電圧の最大値が第3の閾値よりも大きいとの第3条件が成立するか否かを判定する第3の判定部と、
前記第1条件が成立した場合、または、前記第2条件が成立かつ前記第3条件が不成立の場合に、前記地絡検出部による検出出力をロックするロック部とを備える、地絡過電圧継電装置。 - 前記電力系統の停電後に前記各相電圧の少なくとも1つが基準電圧値以上になった場合に、前記第3の判定部は、前記第3条件が成立するか否かの判定を開始する、請求項1または2に記載の地絡過電圧継電装置。
- 前記電力系統に設けられた変圧器の投入を示す情報を受信する受信部をさらに備え、
前記受信部により前記情報が受信された場合に、前記第3の判定部は、前記第3条件が成立するか否かの判定を開始する、請求項1または2に記載の地絡過電圧継電装置。 - 前記第3の判定部は、前記第3条件が成立するか否かの判定を開始してから予め定められた時間が経過した場合に当該判定を停止し、
前記第3の判定部により当該判定が停止された場合、前記ロック部は、前記第1条件または前記第2条件が成立したときに、前記地絡検出部による検出出力をロックする、請求項3または4に記載の地絡過電圧継電装置。
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US11633700B2 (en) | 2020-04-07 | 2023-04-25 | Aqua Membranes Inc. | Independent spacers and methods |
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US10714924B2 (en) | 2020-07-14 |
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