JP2010166667A - Ground-fault directional relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground-fault directional relay that surely achieves ground-fault protection cooperation with a nearest high-order power distribution substation in all power distribution lines. <P>SOLUTION: The ground-fault directional relay is mounted in a ground-fault protection device of a power-receiving facility for private use. The ground-fault directional relay outputs a control signal, which operates a relay of a switch in the ground-fault protection device from an AND circuit via a timing circuit under the condition of input of a determination output signal when a ground-fault direction determined from a phase difference between a zero-phase current and a zero-phase voltage is on the side of a load, together with a zero-phase current determination signal and a zero-phase voltage determination signal, each indicating that a level of the zero-phase current or a level of the zero-phase voltage in an electric path of the power-receiving facility exceeds a prescribed setting value. The setting value about the zero-phase voltage is set to ≤1% on percentage of the zero-phase voltage. A direction/non-direction changeover switch is provided between the AND circuit and the timing circuit so as to selectively switch the control signal or the zero-phase current determination signal and to transmit it to the timing circuit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a ground fault direction relay, more specifically, mainly equipped with a ground fault protection device for a high-voltage power receiving facility for private use, and even if there is a significant change in the distribution system, It is related with the earth fault direction relay which can aim at earth fault protection cooperation of.

  In distribution lines, when a ground fault occurs on at least one of the lines, it is usually necessary to select a part of the distribution line including the ground fault point and effectively shut it off. A ground fault protection device is provided in a high-voltage power receiving facility for home use. As this ground fault protection device, there is a type that detects only zero phase current with a ground fault relay and cuts off the electric circuit, and a type that detects zero phase current and zero phase voltage with a ground fault direction relay and cuts off the electric circuit It is roughly divided into

  FIG. 2 is a single-line diagram of a high-voltage power receiving facility of a power consumer in which each type of ground fault protection device is installed, wherein (a) is for the former type and (b) is for the latter type. . The ground fault protection device shown in FIG. 2A is provided with a switch 47 installed in a lead-in line 52 drawn through a responsibility demarcation point 53 in the power receiving equipment 54 (hereinafter referred to as various types of high-voltage breakers). The switch and the switch are simply referred to as a “switch”), a zero-phase current transformer (ZCT) 43 provided on the power source side, and these devices are electrically connected by input / output lines. A ground fault relay (GR) 45 is provided. The ground fault relay 45 is non-directional, and does not have the selectivity of detecting only the level of the generated zero-phase current and selectively outputting a contact according to the direction of the zero-phase current.

  A zero-phase current generated by a ground fault in the distribution line is detected by the ZCT 43, and a small-phase zero-phase current signal proportional to the zero-phase current is sent to the ground fault relay 45 from its secondary side. The ground fault relay 45 outputs a control signal when the input zero-phase current signal exceeds a preset sensitivity current set value and satisfies a predetermined time limit condition, and operates the relay to switch the switch. 47 is released. However, since the ground fault relay (GR) is non-directional as described above, for example, a ground fault current generated due to a ground fault occurring after ZCT in a private high-voltage power receiving facility of another electric power consumer. However, the ground fault relay 45 operates in spite of the fact that no ground fault has occurred on the premises by flowing to the ZCT 43 of the power receiving equipment 54 shown in FIG. There is a possibility of causing a so-called “getting accident” that opens the switch 47. In addition, when the charging current of the premises (54) is large, it may be difficult to achieve ground fault protection coordination with the most recent distribution substation 40.

  Further, the latter type of ground fault protection device 42 shown in FIG. 2 (b) normally includes a switch 47 installed in an electric circuit 52 that is drawn into a high-voltage power receiving facility 54 via a responsible demarcation point 53, and its power source. A zero-phase current transformer (ZCT) 43 installed in the electric circuit on the side, an instrument transformer (PD) 44 connected to the electric circuit on the load side via a power fuse (PF), and a ground fault direction relay ( DGR) 46. A zero-phase current and a zero-phase voltage generated in the lead-in line 52 due to a ground fault are detected by the ZCT 43 and the PD 44, respectively transformed, and sent to the ground fault relay (DGR) 46. Hereinafter, the output signals from the ZCT 43 and the PD 44 are referred to as “zero phase voltage” and “zero phase current”, respectively.

  The DGR 46 determines whether or not the zero-phase current and zero-phase voltage input thereto exceed a predetermined settling value, and whether the ground fault direction obtained from the phase difference between them is on the load side of the ZCT 43. Determine whether or not. When these conditions are satisfied, a control signal is output to operate the relay, the switch 47 is opened, and the electric circuit 52 is shut off.

  FIG. 3 is a single-line diagram showing a general ground fault protection device installed in a 6 kV distribution substation. The distribution substation shown in this figure includes a circuit breaker (CB) 47 installed on the distribution line drawn from the power bus 41 of the distribution substation 40, and a zero-phase current transformer ( (ZCT) 43 and a ground fault protection device 42 having a ground fault relay 45 is installed. When a ground fault occurs in the distribution line, the zero-phase current generated in the distribution line is detected and transformed by the ZCT 45, and is output to the ground relay 45. The ground fault relay 45 outputs a control signal when the input zero-phase current exceeds a predetermined settling value, and opens the circuit breaker (CB) 47 to cut off this distribution line to protect the distribution line. I am trying.

  If a ground fault occurs in a private high-voltage power receiving facility on the power consumer side, the ground fault protection device in the distribution substation operates and opens the switch before the ground fault protection device in the private high-voltage power receiving facility. However, it is impossible to cut off all distribution lines including the ground fault point on the load side. Therefore, it is necessary to prevent the power outage from spreading due to the accident by operating the ground fault protection device of the high-voltage power receiving facility for private use prior to that of the distribution substation and opening the switch. In this way, in order to emphasize the ground fault protection between the most recent power distribution substation and the private high voltage power receiving equipment, adjust the sensitivity (setting value) of both ground fault (direction) relays. It is necessary to set the ground fault protection device on the high-voltage power receiving equipment side for private use with high sensitivity.

  For ground fault protection devices for distribution substations, for example, regularly implemented every three years, or when there is a change in the distribution system, such as when a new distribution line is installed or the length of the distribution line is greatly changed The settling value is determined based on the result of the artificial ground fault test (DG test). In the case of a 6 kV distribution system, normally, the zero-phase voltage settling value is often set to about 5% at a zero-phase voltage percentage (generated zero-phase voltage / zero-phase voltage x100 at the time of complete ground fault). This set value is notified to each electric power consumer who owns a high-voltage power receiving facility for private use in the distribution area of this distribution substation.

  Each power customer who receives the notification sets a higher sensitivity than the set value notified in the ground fault direction relay of the ground fault protection device on the premises, in order to coordinate ground fault protection with the distribution substation. ing. FIG. 4 is a block diagram showing a general internal configuration of the ground fault direction relay. The ground fault direction relay 2 shown in this figure includes a zero phase voltage level determination unit 16, a zero phase current level determination unit 18, a ground fault direction determination unit 20, an AND circuit unit 22, a time limit circuit 32, an output contact operation 34, a zero phase. A voltage operation display 35 and a zero-phase current operation display 36 are included. The zero-phase voltage level determination unit 16 and the zero-phase current level determination unit 18 include a voltage sensitivity adjustment operation unit 17 and a sensitivity current adjustment operation unit 19, respectively, so that a set value can be set in each operation unit. Yes. These operation units 17 and 19 are normally performed by rotating a rotary switch provided on the display board on the front surface of the ground fault direction relay 2. In the case of the zero-phase voltage, normally, the zero-phase voltage percentage is set to any step of 2.5%, 5.0%, 7.5%, 10%, 15%, for example. Be able to.

JP 2000-156929 A

However, at distribution substations that have large distribution transformers and are responsible for distribution to urban areas, the charging current is currently increasing due to underground distribution facilities and increased customer-side facilities In addition to
(1) When the charging current increases due to the (extension) extension of the distribution line (feeder line) connected to the power bus,
(2) When the distribution system is changed for a short period, such as in substation work or distribution line work performed by the power company, the zero-phase voltage settling value becomes even smaller (higher sensitivity), and the high-voltage power receiving equipment side Furthermore, it is expected that a situation will arise in which the zero-phase voltage settling value of the ground fault direction relay must be set with high sensitivity. In the case of a ground fault direction relay manufacturer or electric power consumer, since the above-mentioned prediction is not made from the viewpoint of an increase in charging current of the electric circuit, no countermeasure has been taken so far, and the predetermined as described above. In the ground fault protection device of the system in which the zero-phase voltage settling value is set only by this step, there is a possibility that the protection coordination cannot be taken on the private high-voltage power receiving equipment side.

  Then, this invention aims at providing the ground fault direction relay which can aim at ground fault protection cooperation with the nearest uppermost substation for distribution in all the distribution lines in order to solve the said subject.

  According to the present invention, the object is that the ground fault protection device of the private power receiving facility is equipped, and the levels of the zero-phase current and the zero-phase voltage generated in the electric circuit in the power receiving facility exceed predetermined set values, respectively. AND circuit with the input of a determination output signal when the ground fault direction determined from the phase difference between the zero phase current and the zero phase voltage is the load side, together with the zero phase current determination signal and the zero phase voltage determination signal indicating In the ground fault direction relay that outputs a control signal for operating the relay of the switch in the ground fault protection device from the time limit circuit, the set value for the zero phase voltage is 1% or less in terms of the percentage of the zero phase voltage. This is achieved by a ground fault direction relay characterized in that.

  That is, the feature of the ground fault direction relay of the present invention is that the ground fault direction is determined from the phase difference between the zero phase voltage and the zero phase current generated in the electric circuit due to the ground fault, and is not based on the result of the DG test. By setting the phase voltage settling value to 1% or less as a percentage of the zero-phase voltage, a difference in sensitivity with the zero-phase current is created, and the zero-phase voltage exceeds the settling value at an early stage. A control signal is output to the switch relay when conditions are satisfied and the zero-phase current exceeds the set value.

  Further, if necessary, a direction / non-direction switch is provided between the AND circuit and the timing circuit so that the control signal or the zero-phase current determination signal is selectively switched and sent to the timing circuit. It can also be configured. Thereby, according to a user's needs, the ground fault direction relay of this invention has an advantage which can be used also as a non-directional ground fault relay.

  By configuring the ground fault direction relay of the present invention as described above, it is possible to ensure ground fault protection coordination with the nearest ground fault protection device in any distribution system, particularly in urban areas, etc. By giving directionality, it is possible to prevent so-called accidents.

It is a block diagram which shows the internal structure of one Embodiment of the ground fault direction relay of this invention. It is a single wire connection diagram including a ground fault protection device in a distribution substation. It is a single line connection diagram including the ground fault protection apparatus in a high voltage power receiving facility for private use. It is an internal block diagram of the conventional ground fault direction relay.

  Hereinafter, the ground fault direction relay of the present invention will be described in detail with reference to embodiments, but the present invention is not limited to the following embodiments.

  FIG. 1 is a block diagram showing an internal configuration of an embodiment of a ground fault direction relay. As shown in this figure, the ground fault direction relay 1 of the present invention mainly includes a zero phase voltage level determination unit 16, a zero phase current level determination unit 18, a ground fault direction determination unit 20, an AND circuit unit 22, a control output unit. 28 parts are provided. The zero-phase current level determination unit 18 includes a sensitivity adjustment operation unit 17.

  The zero-phase voltage level determination unit 16 receives the zero-phase voltage signal input thereto, compares the magnitude thereof with a preset voltage sensitivity (set value), and the zero-phase voltage signal determines the set value. A predetermined zero-phase voltage determination signal is output when it exceeds. The zero-phase voltage level determination unit 16 can include known signal processing circuits such as a filter circuit, an amplifier circuit, and a waveform shaping circuit.

  The voltage sensitivity (setting value) in the zero-phase voltage level determination unit 16 is set to 1% or less as a percentage of the zero-phase voltage. Preferably, this set value is set to an appropriate value in the range of 0.5 to 1%. In particular, in distribution substations equipped with large-capacity distribution transformers in recent years, the ground capacitance tends to increase due to the increase in cable laying, thickening, lengthening, etc. The zero-phase current at the time of the accident increases. For this reason, in urban areas and the like, it can be set at a constant (fixed value) of, for example, 1% in consideration of the fact that the set value of the zero-phase voltage is often 2% or less. In this way, by setting the settling value small and with high sensitivity, it is possible to configure the zero-phase voltage generated in the electric circuit to exceed the settling value at an early stage when a ground fault occurs in the electric circuit.

  The zero-phase voltage level determination unit 16 may be configured to include an operation unit such as a rotary switch that can adjust the voltage sensitivity (setting value) as in the conventional example, or may not include the operation unit. It is preferable that the operation unit is not provided. In this case, the set value of the sensitivity voltage can be stored, for example, in storage means (not shown) provided inside the ground fault direction relay 1 of the present invention so that it can be drawn out in a timely manner. With this configuration, the circuit configuration inside the zero phase voltage level determination unit 16 can be simplified.

  The zero-phase current level determination unit 18 receives a zero-phase current signal from a zero-phase current detection means (not shown) such as ZCT installed in the electric circuit, and the magnitude of the magnitude and a preset sensitivity current (settling value). And a predetermined zero-phase voltage determination signal is output when the zero-phase current signal exceeds the set value. Such functions are analog, digital, and the zero-phase current level determination unit 17 can include a known signal processing circuit such as a filter circuit, an amplifier circuit, and a waveform shaping circuit as appropriate. The setting of the sensitivity current (setting value) in the zero phase current level determination unit 18 can be set by operating an operation device such as a known rotary switch provided in the sensitivity adjustment operation unit 19.

  The ground fault direction determination unit 22 receives the zero-phase current signal and the zero-phase voltage signal extracted from the zero-phase current level determination unit 16 and the zero-phase voltage level determination unit 18, respectively. The current phase difference is obtained, and thereby, the ground fault direction, that is, whether the ground fault point is the power source side or the load side of the ZCT installed in the electric circuit is determined. As a result, when it is determined that the accident point is on the power supply side, no determination signal is output. When it is determined that the load point is on the load side, a direction determination signal is output toward the AND circuit unit 22.

  The AND circuit unit 22 outputs a control signal on condition that each determination signal, that is, a zero-phase current determination signal, a zero-phase voltage determination signal, and a direction determination signal is input thereto.

  The control output unit 28 includes a direction / non-direction changeover switch unit 30 and a time limit circuit 32. The direction / non-direction changeover switch unit 30 receives a control output signal from the AND circuit unit 22 and a zero-phase current determination signal sent via the signal line 26. One of them is output to the subsequent time circuit 32. As the switch unit 30, any conventionally known mechanical type or electric type may be used.

  When a control signal or a zero-phase current determination signal is input from the direction / non-direction changeover switch unit 30 to this, the time limit circuit 32 is configured to output the input signal after a predetermined set time has elapsed.

  The ground fault direction relay of this invention can be provided with a display part (not shown) as needed. In addition to the zero-phase voltage operation display 35 and the zero-phase current operation display 36 shown in FIG. 1, the display unit includes display means such as a zero-phase voltage and zero-phase current level (maximum value) display, an operation display, and a power supply display. Various switches such as an automatic / manual / test return switch and a zero-phase current set value adjustment switch can be arranged.

  Next, the operation of the ground fault direction relay of this embodiment will be described. When a ground fault occurs in the electric circuit, the zero-phase voltage generated in the electric circuit is detected by a zero-phase voltage detecting means (not shown) installed in the electric circuit, and the magnitude of the zero-phase voltage from the secondary side. Is output to the ground fault direction relay 1 of the present invention. The zero-phase current generated in the electric circuit simultaneously with the zero-phase voltage is detected by the zero-phase current detecting means, and the zero-phase current signal of a small force proportional to the zero-phase current is detected from the secondary side of the ground fault direction of the present invention. The signal is output toward the relay 1 (see FIGS. 1 and 2). Here, as the zero-phase voltage detection means, an instrument transformer (PD), a zero-phase voltage transformer (ZPD, also referred to as a zero-phase reference input device), or the like can be suitably used. The zero phase voltage detection means includes a zero phase current transformer (ZCT). Moreover, you may make it obtain | require a zero phase electric current by carrying out vector composition of the measurement result using three current transformers (CT).

  When this zero-phase voltage signal is input via the input terminal 13, the zero-phase voltage level determination unit 16 determines the magnitude of the input signal compared with the set value set as a fixed value. As a result of the determination, when the input signal is smaller than the set value, no signal is output, and when it is larger, a zero-phase voltage determination signal is output. This zero-phase voltage determination signal is sent to the AND circuit unit 22.

  When this zero-phase current signal is input to the zero-phase current level determination unit 18 via the input terminal 14, the magnitude thereof is compared and determined with a preset value of the sensitivity current. As a result of the determination, when the input signal is less than or equal to the set value, no signal is output. When the input signal exceeds the set value, a zero-phase current determination signal is output to the AND circuit unit 22 and the signal line 26 Is sent to a direction / non-direction selector switch 30 in the control output unit 28 to be described later.

  Also, the zero-phase voltage level determination unit 16 and the zero-phase current level determination unit 18 respectively send a zero-phase voltage signal and a zero-phase current signal to the ground fault direction determination unit 20, and based on the phase difference between the two signals. A ground fault direction is determined. As a result of the determination, there is no signal output when the ground fault direction is closer to the power supply side than the ZCT, and a direction determination signal is sent to the AND circuit unit 22 when it is on the load side.

  The AND circuit unit 22 outputs a control signal on condition that each determination signal, that is, a zero-phase current determination signal, a zero-phase voltage determination signal, and a direction determination signal is input thereto.

  The control output unit 28 includes a direction / non-direction changeover switch unit 30 and a time limit circuit 32. The direction / non-direction changeover switch unit 30 receives a control output signal from the AND circuit unit 22 and a zero-phase current determination signal sent via the signal line 26, and switches one of these by switching the switch. One of them can be output to the subsequent time circuit 32. As this switch part 30, either a conventionally known mechanical type or electric type may be used. Therefore, the operator may directly operate this to switch between direction and non-direction. You may be comprised so that it may switch by a certain signal.

  In the control output unit 28; the output signal that has passed through the time limit circuit 32 activates a contact point of a switch (not shown) operation relay installed in the electric circuit (see reference numeral 34 in FIG. 1). The control output unit 28 includes a known self-holding circuit and its release circuit, and the like, and may hold the output state of the output signal so that the self-holding state can be released by, for example, an external signal input. . Further, if necessary, digital signal processing can be performed including a sample and hold circuit, an A / D conversion circuit, and the like. The control output unit 28 can also output signals for a zero-phase voltage operation display 35 and a zero-phase current operation display 36 as necessary.

  Thus, when the zero-phase voltage signal and the zero-phase current signal are generated in the electric circuit due to the ground fault, the ground fault direction relay 1 according to the present invention firstly provides the zero-phase voltage signal exceeding the set value condition, and then the zero-phase voltage signal. Provided with a condition for exceeding the settling value of the current signal, and on the condition that the ground fault direction determined from the phase difference between the two input signals satisfies the predetermined condition, the electric circuit is interrupted after a predetermined time has elapsed, and the load device, etc. Can be protected. In addition, since both the zero-phase current determination signal and the zero-phase voltage determination signal are required for the condition for operating the switch relay in this way, the risk of unnecessary operation is significantly reduced.

  Furthermore, the ground fault direction relay 1 of the present invention can be used as a non-directional ground fault relay by switching the direction / non-direction changeover switch unit 30 and outputting a zero-phase current determination signal to the switch relay. it can. As a result, this non-directional ground fault relay is used due to circumstances such as when it is used as a temporary mobile cubicle for construction work, when it is used outside urban areas, or there are multiple power receiving facilities on the premises. It can be used effectively when there is a need of electric power consumers such as wanting.

DESCRIPTION OF SYMBOLS 1 Ground fault direction relay 13 Zero phase voltage input terminal 14 Zero phase current input terminal 16 Zero phase voltage level determination part 17 Zero phase voltage sensitivity setting operation part 18 Zero phase current level determination part 19 Zero phase current sensitivity setting operation part 20 Ground fault Direction determination unit 22 AND circuit unit 24 AND circuit output line 26 Zero-phase current signal output line 28 Control output unit 30 Direction / non-direction switching switch unit 32 Time limit circuit unit 34 Output contact operation 35 Zero-phase voltage operation display 36 Zero-phase current operation Display 40 Distribution substation 41 Power bus 42 Ground fault protection device 43 Zero-phase current transformer (ZCT)
44 Capacitor-type instrument transformer (PD)
45 Ground fault relay (GR)
46 Ground fault relay (DGR)
47 Circuit breaker 51 Distribution line 52 High voltage lead-in line 53 Responsible demarcation point 54 High voltage power receiving facility CB Circuit breaker LBS High voltage AC load switch PF Power fuse PCT Instrument transformer

Claims (2)

  A zero-phase current determination signal and a zero-phase signal, which are installed in a ground fault protection device for a private power receiving facility, indicate that the levels of the zero-phase current and the zero-phase voltage generated in the electric circuit in the power receiving facility have exceeded predetermined set values, respectively. The ground fault protection from the AND circuit through the time limit circuit on condition that the judgment output signal is input when the ground fault direction determined from the phase difference between the zero phase current and the zero phase voltage is the load side together with the voltage judgment signal A ground fault direction relay for outputting a control signal for operating a relay of a switch in the apparatus, wherein a set value for the zero phase voltage is 1% or less in terms of a percentage of the zero phase voltage. .   A direction / non-direction switch is provided between the AND circuit and the time circuit, and is configured to selectively switch the control signal or the zero-phase current determination signal and send it to the time circuit. Item 3. The ground fault direction relay according to item 1 or 2.

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