WO2004042883A1

WO2004042883A1 - Protective relay

Info

Publication number: WO2004042883A1
Application number: PCT/JP2002/011571
Authority: WO
Inventors: Yasushi Takeuchi; Susumu Tanaka
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 2002-11-06
Filing date: 2002-11-06
Publication date: 2004-05-21
Also published as: CN100438248C; CN1618156A; JPWO2004042883A1

Abstract

A protective relay for a system where an interconnection breaker is installed at the interconnection point between a commercial-side bus and an important load power supply-side bus. A reverse power detecting means is provided. Therefore, when a commercial power supply side open fault occurs, the interconnection breaker is operated to prevent outflow of reverse power and thereby to protect the important load. A short-circuit fault occurring on the load side is judged from the present/absence of operation of a direction short-circuit element whether or not it occur on the general load side. If it is judged it has occurred on the general load side, the interconnection breaker is operated; whereas if it is judged that it has occurred on the important load side, the interconnection breaker is not operated to protect the important load.

Description

Protection relays

The present invention relates to a protective relay, and in particular, a system used in a system in which a circuit breaker is disposed at a connection point between a commercial side bus and an important power supply side bus such as a private generator side bus.

The present invention relates to a protective relay for interconnection. Background art

book

The conventional protective relay for grid connection is used in the circuit configuration of Fig.5. Although this figure is shown as a single line for simplicity, it is actually composed of three-phase three-wire lines. In FIG. 5, 1 indicates a private generator, 2 indicates a private generator side bus bar, and 3 indicates a significant load supplied by the private generator 1. Further, 4 indicates a commercial power inlet, 5 is a commercial-side bus, and 6 indicates a general load powered by commercial power drawn from the inlet 4. The generator generator side bus 2 and the commercial bus 5 are interconnected by the interconnection breaker 7. Reference numerals 8 and 9 respectively indicate voltage transformers and current transformers installed on the wires from the commercial side bus 5 to the commercial power inlet 4. Reference numeral 10 denotes a protective relay, which detects an under voltage element and a directional short circuit element using voltage and current acquired by the voltage transformer 8 and the current transformer 9 and detects a fault such as a short circuit accident. , Output a breaker open signal to breaker 7.

The operation will be described. As described above, the private generator side bus bar 2 and the commercial side bus bar 5 are interconnected via the circuit breaker 7, and the operation of the interconnection circuit breaker 7 is controlled by the protective relay 10. The protective relay 10 has an under voltage element (under voltage detection means) and a direction short element (direction short element), and a voltage transformer 8 and a current transformer 9 used as sensors are connected from the commercial side bus 5 to a commercial line. It is placed on the power line on the receiving side to the power inlet 4.

The under voltage component is the voltage 3 detected by the voltage transformer 8 and the voltage value of the three phases decreases. It detects that the value is below a certain value, and operates when a short-circuit accident occurs on the 3rd and 3rd important loads.

The directional short circuit element is used to detect reactive power flowing out of the commercial power into the substation, and operates when a short circuit accident occurs in a power company's substation.

For this reason, when an open accident occurs at the commercial power inlet 4, the direction short-circuiting element of the protective relay 10 does not operate, and thus the interconnection breaker 7 may not operate. At that time, the private generator 1 bears the power supply to the general load 6 side. As a result, the in-house generator 1 may be overloaded, and the in-house generator 1 may be damaged.

On the other hand, for the short circuit fault 1 3 and 1 2 that occur on the critical load 3 side and the general load 6 side, the undervoltage element operates and the interconnection breaker 7 operates. If a short circuit accident 12 occurs on the general load 6 side, the voltage drop in the important load 3 can be suppressed by disconnecting the connection breaker 7. However, if a short circuit accident 13 occurs on the important load 3 side, the short-circuit current will be supplied from the private generator 1 even after the interconnection breaker 7 operates, resulting in an overload condition. . After that, when the point of short circuit accident 1 3 is disconnected by the feeder circuit breaker 1 1, the load changes to the light load state and the load returns to normal. This series of operations increases the torque fluctuation of the private generator 1, so damage to the private generator 1 can not be made and the important load 3 can not be protected.

As described above, in the case of the conventional protective relay, there was a possibility that the important load and the private generator could not be protected in the case of the commercial power source side open accident and the important load side short circuit accident. Disclosure of the invention

The present invention is a protective relay capable of protecting important loads and power sources for important loads even in the event of a utility power source side open accident and a critical load side short circuit accident. In the present invention, the power source for important load includes, for example, a generator for private use, a power generation facility such as a fuel cell, or a highly reliable commercial power source.

The protective relay of the present invention reliably operates the circuit breaker at the time of a commercial power source side open accident. Reverse power factor is added to make it happen. Also, change the mounting position of the voltage transformer and current transformer used as a sensor for protective relay to the commercial bus side of the interconnection breaker, and distinguish between a critical load side short circuit accident and a general load side short circuit accident. It can be so. In the event of a utility power supply side opening accident, the power supply for the critical load bears power supply to the general load, and there is a possibility that the voltage supplied to the critical load may decrease. Therefore, open the circuit breaker and connect the critical load. Protect.

In the case of a critical load side short circuit accident, it is judged whether it is a serious load side short circuit accident or a general load side short circuit accident based on the presence or absence of a directional short circuit element detection. When it is detected that an accident is detected, the accident point on the important load side is disconnected by the feeder breaker without operating the interconnection breaker, and the overload status is restored to the normal status. Protect the critical load power source from damage. That is, the present invention relates to a protective relay provided in a system in which an interconnection breaker is disposed at an interconnection point between a commercial side bus to which a general load is connected and a power supply side bus to an important load to which a significant load is connected. Based on the input means to which the voltage and current at the commercial side bus are respectively input, and the values of the voltage and the current, reverse power outflow from the important load power supply side bus to the commercial side bus Reverse power detection means for detecting; and breaker open signal output means for outputting a breaker open signal for opening the above-mentioned linked breaker when the reverse power detection means detects a power outflow in the reverse direction. And have. In addition, by detecting that the voltage value of the commercial side bus bar is less than a predetermined fixed value based on the voltage and the value of the current, either the general load side or the important load side can be detected. And detecting the presence or absence of the outflow reactive power based on the under voltage detection means for judging that the short circuit accident has occurred, and the values of the above voltage and the above current. Directional short circuit detection means for determining whether a short circuit accident has occurred on the general load side or the important load side, and the directional short circuit detection means has determined that the short circuit accident has occurred on the general load side Further, circuit breaker open signal output means for outputting a circuit breaker open signal for opening the above-mentioned connected circuit breaker. Brief description of the drawings FIG. 1 is a circuit diagram showing an example of a circuit to which a protective relay according to the present invention is applied. FIG. 2 is a configuration diagram showing an internal configuration of a protective relay according to the present invention.

FIG. 3 is an explanatory view showing determination areas of reverse power elements and direction short elements of the protective relay according to the present invention.

FIG. 4 is an explanatory view showing detection contents and protection contents of a reverse power element, a direction short element, and an under voltage element of the protective relay according to the present invention.

FIG. 5 is a circuit diagram showing an example of a circuit to which a conventional protective relay is applied. BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1.

The protective relay of the present invention controls an interconnection breaker installed on a bus that interconnects a commercial power supply side and a power supply side for an important load. FIG. 1 shows an example of a circuit of a system to which the protective relay 14 of the present invention is applied, and FIG. 2 shows the internal configuration of the protective relay 14 of the present invention. In FIG. 1, the same components as those in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted here. Further, the power source for important loads according to the present invention includes, for example, all reliable power source devices such as a private generator, a power plant such as a fuel cell, or a highly reliable commercial power source. However, in the following description, a generator for private use will be described as an example as a power source for important loads.

One of the differences between the configuration of Fig. 1 and the above-mentioned conventional example shown in Fig. 5 is that the voltage transformer 15 for input to the protective relay 14 and the connection position of the current transformer 16 are interconnected. It has been changed to the commercial bus 5 side of the circuit breaker 7. At this time, there is no load connection between the connection breaker 7 and the voltage transformer 15 and the current transformer 16. With this configuration, when a short circuit accident occurs on the load side, it is determined whether it is a short circuit accident on the important load side or a short circuit accident on the general load side, and the accident occurred on the important load side. If it is detected that a short circuit has occurred, disconnect the point of failure on the heavy load side with the circuit breaker for feeders without operating the connection breaker, and restore the overload status to the normal status. , Protect private generators from damage.

Also, as a second difference, instead of the protective relay 1 4 power under voltage element, It has reverse power element (reverse power detection means). As a result, the protective relay 14 according to the present invention has a directional shorting element and a reverse power element. Figure 4 shows the detection content and protection content of these elements. As shown in FIG. 4, the reverse power element detects that the power flows out from the generator generator side bus 2 to the commercial side bus 5. When the power transmission from the commercial power inlet 4 is stopped, as shown in FIG. It works. By adding the reverse power element, when the opening accident of the commercial power inlet 4 which could not be detected conventionally occurs, the opening accident is surely detected, and the interconnection breaker 7 operates. Prevent the outflow of reverse power, suppress the voltage drop, and protect the important load 3 and the private generator 1.

In the protective relay 14, as shown in FIG. 2, the values of voltage 3 phase and current 3 phase detected by the voltage transformer 15 and the current transformer 16 are inputted and amplified. An amplification circuit 17. A filter circuit 18 which receives the signal output from the amplifier circuit 17 and receives only the predetermined frequency component of the amplifier circuit 17 and an analog signal output from the filter circuit 18 is input. , Analogue digital conversion AZD converter 19 and the digital converted signal is input, and based on them, the fault is detected by monitoring the under voltage element, the reverse power element and the short circuit direction element An arithmetic processing unit 20 is provided.

The operation will be described. First, the input from the voltage transformer 15 and the current transformer 16 is input to the inside of the protective relay 14, and A / D conversion is performed through the amplifier circuit 1 7 and the filter circuit 18 inside the protective relay 14. Converted to the input to the unit 19, converted from analog data to digital data by the AZD converter 19, input the converted digital data to the operation processing unit 20, and a failure at the operation processing unit 20 Make a decision. If a failure is detected, the connection circuit breaker open signal is output to shut off the connection circuit breaker 7, and the connection circuit breaker 7 is opened.

The arithmetic processing unit 20 of the protective relay 14 calculates the electric power moving at the interconnection point from the digital data taken from the A / D converter 19 power, and determines the reverse power element and the short circuit direction element carry out. Figure 3 shows each judgment area. In FIG. 3, active power (plus, minus) and reactive power (lead, lag) are orthogonal axes, and the judgment region of each element is indicated by reference numeral 30. That is, the hatched range 3 0 The reverse power element and the short circuit direction element respectively operate when the reactive power calculation result and the active power calculation result are both included in. At this time, the direction of power flow from the commercial side bus 5 to the private generator side bus 2 is positive. As apparent from FIG. 3, the reverse power element operates when the active power calculation result becomes negative, and the short direction element operates when the reactive power calculation result becomes forward. In the event of a commercial power supply side open accident, since the reverse power factor is detected because the generator 1 supplies active power from the private generator 1 to the general load 6, the grid breaker 7 is opened to cause outflow of the reverse power. Protection and protect the important load 3 by suppressing the voltage drop. As described above, in the present embodiment, the overload state of the private generator 1 generated in the commercial power source side open accident is detected by the reverse power element, and the interconnection breaker 7 is opened. Important load 3 can be protected by quickly recovering the overload condition and suppressing the voltage drop of the private generator 1.

In the present embodiment, the case has been described where the protective relay 14 has two, the direction short circuit element and the reverse power element, but the present invention is not limited to this case. In order to detect an accident, only reverse power elements are required. Second Embodiment

In the circuit shown in the first embodiment described above, when a short circuit fault 12 on the general load 6 side occurs, reactive power is detected as the lead direction, and therefore, a directional short element is detected. Therefore, in the present embodiment, this disconnects the interconnection breaker 7 to prevent the outflow of reactive power and the voltage drop.

On the other hand, when a short circuit accident 13 on the critical load 3 side occurs, reactive power is detected as the delay direction, so no directional short circuit element is detected. At this time, without opening the interconnection breaker 7, at the accident point of short circuit 13, the current supplied from the commercial power source side suppresses the current supplied from the private generator 1, and the short circuit accident 1 3 Disconnect the fault point of the feeder by opening the feeder breaker 1 1 and restore the load to the normal condition. As a result, damage to the private generator 1 can be prevented, and continuous operation of the important load 3 and the private generator 1 becomes possible.

In addition, as a method of determining whether or not the short circuit accident 13 has occurred, for example, as shown in FIG. In this case, a protective relay for feeders (individual protective sensor / relay) 2 1 is provided in advance for circuit breaker 1 1, and in the event of an accident at a point 13, protective relay 1 4 Since the short-circuit direction element does not detect it, the protective relay 2 for feeder detects an over-current element, and outputs an open command to the circuit breaker 1 1 to open the circuit breaker 1 1. Just do it. In Fig. 1, the protective relay 2 for feeders is provided only in the breaker 11. However, this is for the purpose of simplification of the figure. It is desirable to provide a protective relay.

As described above, when a short circuit accident 1 3 and 1 2 occurs on the critical load 3 side and the general load 6 side, which short circuit accident has occurred is determined based on the presence or absence of the directional short circuit element, and the critical load 3 side short circuit When the accident 13 occurs, by not opening the connection breaker 7, damage to the private generator 1 can be prevented, and continuous operation of the important load 3 and the private generator 1 can be enabled.

In the present embodiment, the case has been described where the protective relay 14 has two, the direction short circuit element and the reverse power element, but the present invention is not limited to that case, and the important load side or general In order to detect a load-side short circuit fault, only a directional shorting element is sufficient. Embodiment 3.

In Embodiments 1 and 2 described above, an example in which the overload condition of the private generator and the short circuit accident on the important load side are detected at high speed, and the interconnection breaker open signal is output to the interconnection breaker 7. As described above, in the present embodiment, a high speed breaker capable of half cycle breaking is used as the connection breaker 7, and the total breaking time of the disconnection system is accelerated.

If the operation time of the protective relay 14 is 5 ms or less from the abnormal start due to the fault occurrence, and the interrupting time of the interconnection breaker 7 consisting of high-speed circuit breakers is 114 ms or less, the total interrupting time Since the time from detection to circuit breaker opening is expressed by the sum of these, operation of less than 14. 4 ms is possible, and disconnection can be achieved in one cycle or less from the failure occurrence.

As described above, in the present embodiment, a parallel connection of 14.4 ms or less after occurrence of a failure It is possible to protect the important load 3 connected. Embodiment 4.

In the present embodiment, in addition to the direction short circuit element and the reverse power element used by the protective relay 14 in the first and second embodiments described above, the arithmetic processing unit 20 quickly determines the voltage drop at the time of an accident. It is possible to add an under voltage component to reduce the impact on critical load 3 due to voltage drop. Figure 4 shows the detection content and protection content of each element.

In the circuit shown in the first embodiment, when a short circuit accident 13 or 12 occurs on the important load 3 side and the general load 6 side, the undervoltage element operates in either case. Therefore, it is not possible to determine at which load side a short circuit accident has occurred only by the operation of the undervoltage element.

Therefore, in this embodiment, a short circuit fault on the load side is detected by detecting the under voltage element, and a short circuit fault on the load side is detected by either the important load side or the general load side by detecting the directional short circuit element. Determine if it is a short circuit accident on the side.

Note that it is also possible to separately detect both the operation of the under voltage element and the operation of the direction short circuit element to determine which load side of the loads the short circuit accident has occurred. Use this to determine the logical product of the under voltage element and the direction short element.

The detection time of the voltage drop of the protective relay of the present invention realizes less than 3.5 ms from the start of the voltage drop, and the breaking time of the high-speed circuit breaker described in the third embodiment is less than 14.4 ms. In combination with this, the total cutoff time in the present embodiment is less than 14.9 ms.

As described above, in the present embodiment, since it is possible to carry out disconnection of 14.9 ms or less from the occurrence of a failure, the important load 3 connected can be protected. In the above first to fourth embodiments, although the example of inputting the values of the voltage 3 phase and the current 3 phase to the protective relay 14 has been described, the present invention is not limited to that case. From the voltage of R-S phase and S-T phase. Since the voltage of T_R phase can be determined, two phases of input may be used, and the same effect can be obtained in that case. Industrial Applicability

As described above, in the protective relay according to the present invention, the undervoltage element, the reverse power element, and the short circuit direction used when connecting the commercial side bus bar and the private generator side bus bar at the office having the private power generation facility. It is useful as a protection relay that detects elements at high speed and opens the circuit breaker at the connection point.

Claims

The scope of the claims

1. A protective relay provided in a system in which an interconnection breaker is disposed at an interconnection point between a commercial side bus to which a general load is connected and a power supply side bus to an important load to which an important load is connected, the commercial relay described above Based on the input means to which the voltage and current at the side bus are input, and the above voltage and the value of the current, detect the power outflow in the reverse direction from the power side bus for the important load to the commercial side bus. Reverse power detection means

And a first circuit breaker opening signal output unit for outputting a circuit breaker opening signal for opening the connection circuit breaker when the reverse power detection unit detects a power outflow in the reverse direction. Features a protective relay.

2. Directional short circuit detection that determines whether a short circuit fault has occurred on the general load side or the important load side by detecting the presence or absence of the outflow reactive power based on the voltage and the value of the current Means,

When the directional short circuit detection means determines that the short circuit accident occurred on the general load side, a second circuit breaker open signal output that outputs a circuit breaker open signal for opening the interconnected circuit breaker. Means and

The protective relay according to claim 1, further comprising:

3. A protective relay provided in a system in which an interconnection breaker is disposed at an interconnection point between a commercial side bus bar to which a general load is connected and an important load power source side bus bar to which a significant load is connected, the above commercial line The short circuit accident detected by the under voltage detection unit is detected by detecting the presence or absence of the outflow reactive power based on the input unit to which the voltage and the current in the side bus are respectively input and the value of the voltage and the current. Directional short circuit detection means for determining which of the general load side and the important load side has occurred;

The direction short circuit detection means determines that the short circuit accident occurred on the general load side Circuit breaker open signal output means for outputting the circuit breaker open signal for opening the above-mentioned connection breaker, and

A protective relay characterized by having.

4. By detecting that the voltage value of the commercial side bus bar is equal to or less than a predetermined constant value based on the voltage and the value of the current, either the general load side or the important load side can be detected. Further equipped with under voltage detection means to determine that a short circuit has occurred,

The directional short circuit detection means detects the presence or absence of the outflow reactive power based on the voltage and the value of the current, thereby detecting the short circuit accident detected by the undervoltage detection means and the general load side and the important side. Determine which side on the load side it occurred

The protective relay according to claim 2 or 3, characterized in that:

5. The above-mentioned connected circuit breaker consists of a high-speed circuit breaker that can shut off a half cycle.

Assuming that the operation time of the protective relay is 5 ms or less from the abnormal start due to failure occurrence, and the cut-off time of the above-mentioned circuit breaker is 1 1.4 ms or less, the total cut-off time is 1 cycle or less from the failure occurrence. The protective relay according to any one of claims 1 to 3, characterized in that: