TW200409429A - Protective relay - Google Patents

Abstract

A protective relay, used in a system wherein the connection point of commercial bus and power source bus for an important load is provided with a connection breaker, is disclosed. A reverse power detection means is arranged in the protective relay. When a trouble occurs on the commercial power side, the connection relay is actuated to prevent the flow-out of reverse power so as to protect the important load. Further, when a short circuit incident happened on the load side is detected, by whether a directional short circuit element acts or not, to be that happened on the general load side, the connection breaker is actuated. When the short circuit incident is detected to be that happened on the important load side, the connection breaker will not be actuated, whereby the important load is protected.

Description

200409429 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to protection relays, particularly to the connection points of power-side busbars for important loads such as commercial-side busbars and user-specific generator-side busbars. Protective relay for system connection in the system. [Prior Art] A conventional protective relay for system connection uses the circuit configuration of FIG. 5. Of course, this diagram is made to simplify the single-line diagram, but in fact, it is composed of three-phase and three-wire lines. In FIG. 5, 1 indicates a user-specific generator, 2 indicates a user-specific generator-side bus, and 3 indicates an important load supplied by the user-specific generator 1. In addition, 4 is a lead-in hole for commercial power, 5 is a commercial-side bus bar, and 6 is a general load for commercial power supply power introduced through the lead-in hole 4. The customer-specific generator-side bus 2 and the commercial-side bus 5 are connected by a connection breaker 7. 8 and 9 are transformers and converters provided on the wires from the commercial side busbar 5 to the commercial power introduction line hole 4, respectively. 1 0 series protection relays use the voltage and current obtained by transformer 8 and converter 9 to detect insufficient voltage and directional short-circuit components. When a fault such as a short-circuit accident is detected, a circuit breaker disconnection signal is output to circuit breaker 7 ° Describe the action. As described above, the user-specific generator-side bus bar 2 and the commercial-side bus bar 5 are connected via the circuit breaker 7, and the operation of the connection breaker 7 is controlled by the protection relay 10. The protective relay 10 has an under-voltage element (under-voltage detection mechanism) and a directional short-circuit element (directional short-circuit detection mechanism). The transformer 8 and the converter 9 used as sensors are arranged on the commercial side bus 5 to the commercial power introduction line. On the electric wire on the power receiving side of hole 4.

314164.ptd Page 7 200409429 V. Description of the invention (2) The under-voltage element is a component whose three-phase voltage value of the voltage detected by the detection transformer 8 will be lower than a fixed value, which is on the 3 side of the important load and the f side of the general load. Act in the event of a short circuit. A directional short-circuit element is a component that detects reactive power (Reactive Power) flowing to commercial power transformer equipment and is activated when a short-circuit accident occurs in a power company's transformer facility. Since the directional short-circuit element of the protection relay 10 does not operate in the case of a disconnection accident in the lead-in hole 4 of the commercial power, the connection breaker 7 may not operate. • On the other hand, for short-circuit accidents 1 3 and 12 on the important load 3 side and the normal load 6 side, the under-voltage element is activated, and the connection breaker 7 is activated. In the case where the short-circuit accident 12 occurs on the side of the general load 6 and also after the connection breaker 7 is actuated, a short-circuit current is supplied from the user-specific generator 1 to an overload condition, and the load returns to normal. Since the torque variation of the user-specific generator 1 is increased due to a series of actions, the user-specific generator 1 is damaged and cannot protect important loads. In this way, in the conventional protection relay, in the case of a commercial power supply side disconnection accident and an important load side short circuit accident, there is a possibility that the important load cannot be protected and the generator is used. [Contents] The present invention is a protective relay that can protect important loads and power sources for important loads in the event of a commercial power supply side disconnection accident and an important load side short circuit accident. Moreover, in the present invention, the power source for important loads includes, for example, power generation equipment such as a user-specific generator, a fuel cell, or a commercial power source with high reliability.

Page 8 314164.ptd 200409429 V. Invention Description (3) etc. are included. The protection relay of the present invention is provided with a reverse power element in order to ensure that the circuit breaker for connection is operated in the event of a disconnection on the commercial power source side. In addition, the installation position of the transformer and converter used as the sensor of the protective relay was changed to the commercial bus side of the circuit breaker for connection, so that short-circuit accidents on the important load side and short-circuit accidents on the general load side could be judged. When a disconnection accident occurs on the commercial power supply side, the power supply for the important load needs to bear the power supply to the general load, and there may be a voltage drop when the power is supplied to the important load. Therefore, the circuit breaker for the connection is disconnected to protect the important load. . In addition, when a short-circuit accident occurs on the important load side, it is judged based on whether the directional short-circuit element detects a short-circuit accident on the important load or a short-circuit accident on the general load side, and detects that it is a short-circuit accident on the important load side. In this way, the short-circuiting device for the connection is not activated, the accident point on the important load side is cut off by the power-supply breaker, and the overload condition is restored to a normal state, thereby protecting the power supply for the important load from being damaged. That is, the present invention is a protective relay of a system provided with a circuit breaker for connection provided at a connection point between a commercial side bus connected to a general load and an important load power side bus connected to an important load. The invention includes: an input mechanism for inputting The voltage and current of the commercial-side bus; the reverse power detection mechanism detects the reverse power outflow from the power-source-side bus for important loads to the commercial-side bus based on the value of the voltage and the current; and the circuit breaker disconnection signal output mechanism. 'When the reverse power detection mechanism detects the outflow of reverse power, a circuit breaker disconnection signal for opening the connection breaker is output.

314164.ptd Page 9 200409429 V. Description of the invention (4), it also includes: undervoltage detection mechanism, which detects that the voltage value of the commercial-side bus is below a predetermined value based on the value of the voltage and the current, and Determining which of the general load side and the important load side the short-circuit accident occurred; the directional short-circuit detection mechanism detects the presence or absence of reactive power based on the values of the voltage and the current, and determines the under-voltage detection mechanism. Which of the detected short-circuit accidents occurred on the general load side and the important load side; and the circuit breaker disconnection signal output mechanism determines that the short-circuit accident occurred on the general load by the directional short-circuit detection mechanism. When it is on the side, it outputs the breaker disconnection signal used to disconnect the above-mentioned Θ breaker. [Embodiment] The first embodiment The protection relay of the present invention is a protection relay that controls a circuit breaker for connection provided to a busbar connecting a commercial power source side and a power source side for a load. Figure _1 shows a circuit diagram of a system to which the protective relay 14 of the present invention is applied,-Figure 2 shows the internal structure of the protective relay 14 of the present invention. In Fig. 1, the same structures as those in Fig. 5 are designated by the same reference numerals, and a description thereof will be omitted. In addition, the important load power source of the present invention includes, for example, power generation equipment such as a user-specific famous machine, a fuel cell, or a highly reliable commercial power source Θ as long as it is a highly reliable power source device. However, it will be described in the following description. An example of a user-specific generator as a power source for important loads will be described. The difference between the structure of Fig. 1 and the conventional example shown in Fig. 5 lies in the installation position of the transformer 15 and the converter 16 for inputting the protective relay 14

314164.ptd Page 10 200409429 V. Description of the invention (5) Change to the commercial bus 5 side of the circuit breaker 7 for connection. At this time, no-load connection is made between the connection breaker 7, the transformer 15 and the converter 16. With this structure, when a short-circuit accident occurs on the load side, it is judged as a short-circuit accident on the important load side or as an open-circuit accident on the general load side. When a short-circuit accident on the important load side is detected, the connection is used. The circuit breaker does not operate, and the accident point on the important load side is cut off by the feeder circuit breaker to restore the overload state to the normal state, thereby protecting the user-specific generator from damage. In addition, the second difference is that the protective relay 14 has a reverse power element (reverse power detection mechanism) instead of an undervoltage element. Accordingly, the protection relay 14 of the present invention has a directional short-circuit element and a reverse power element. Figure 4 shows the detection content and protection content of these components. As shown in Figure 4, the reverse power element is a component that detects power flowing from the user-specific generator-side bus 2 to the commercial-side bus 5 and operates when commercial power stops transmitting power from the lead-in hole 4. By adding a reverse power element, when a disconnection accident that could not be detected in the past occurred in the inlet 4 of commercial power, the disconnection accident was definitely detected, and the connection breaker 7 was operated to prevent reverse power Flow, suppress pressure drop, protect important load 3 and user-specific generator 1. As shown in Fig. 2, an amplifying circuit 17 is provided in the protective relay 14, which uses the transformer 15 and the converter 16 to input the detected voltage three-phase and current three-phase values to amplify these values; filtering The amplifier circuit 18 inputs signals output from the amplifier circuit 17 only through the predetermined frequency components of these signals; the A / D analog / digital (A na 1 〇g / D git) converter 19, whose input is self-filtered Analog signals output by the amplifier circuit 18 for analog / digital conversion; and arithmetic processing

314164.ptd Page 11 200409429 V. Description of the Invention (6) Part 20, which inputs this signal after digital conversion, and monitors the insufficient voltage element, reverse power element and directional short circuit element based on this signal to detect the fault. The action will be explained. First, the inputs from the transformer 15 and the converter 16 are routed to the inside of the protective relay 14, and the amplifier circuit 17 and the filter circuit 18 inside the protective relay 14 are converted into a pair A / D converter. 1 9 • The input is converted from analog to digital by the A / D converter 19, and the converted digital data is input to the arithmetic processing section 20, and the arithmetic processing section 20 is used for fault determination. When a fault is detected, a disconnection signal for disconnecting the circuit breaker for connection I and a circuit breaker 7 for disconnecting are output. The calculation processing unit 20 of the protection relay 14 calculates the power moving at the connection point from the digital data taken from the A / D converter 19, and implements the judgment of the reverse power element and the directional short-circuit element. Figure 3 shows the individual determination areas. In Figure 3-the active power (positive and negative) and reactive power (leading, lagging) (lead, lag) are represented by orthogonal axes, and the symbol 30 is used to represent the individual components. region. That is, in the case where both the reactive power calculation result and the active power calculation result enter the range of the shaded line in the day 30. The reverse power element and the directional short-circuit element operate separately. At this time, the power calculation is based on the direction in which the commercial-side busbar 5 flows to the user-specific generator-side busbar 2. As shown in Figure 3, the reverse power element operates when the active power calculation result is negative, while the directional short-circuit element operates when the reactive power calculation result is ahead. When the commercial power supply side disconnection accident occurs, since the user_dedicated generator 1 supplies active power to the general load 6, the reverse power element detects the accident, thereby disconnecting the circuit breaker 7 to prevent reverse Power flow

314164.ptd Page 12 200409429 V. Description of the invention (7) It is shown that the important load is protected by suppressing the voltage drop3. As described above, in this embodiment, the reverse power element is used to detect the overload state of the user-specific generator 1 caused by the disconnection accident on the commercial power source side, and the connection breaker 7 is disconnected, thereby quickly recovering the fault. The load state can protect the important load by 3 ° by suppressing the voltage drop of the user-specific generator 1. Furthermore, in this embodiment, the case where the protective relay 14 has both a directional short-circuit element and a reverse power element will be described. However, it is not limited to this case, it may only have a reverse power element to detect a disconnection accident on the commercial power supply side. Second Embodiment In the circuit shown in the first embodiment described above, when a short-circuit accident 12 occurs on the 6 side of a general load, the reactive power becomes a leading direction after being detected, so the directional short-circuit element detects it. Therefore, in this embodiment, the circuit breaker 7 is disconnected to prevent the outflow of reactive power and the voltage drop. On the other hand, since the short-circuit accident 13 occurred on the side of the important load 3, after detection, the reactive power became a lagging direction, so the directional short-circuit element was not detected. At this time, the circuit breaker 7 for connection is not disconnected, and the current supplied from the commercial power source side is used to suppress the supply current from the user-specific generator 1 at the point of the short-circuit accident 13, and the circuit breaker 11 for the power supply is disconnected , Cut off the accident points of short circuit accidents 13 and make the load return to normal state. This prevents damage to the user-specific generator 1 and allows the important load 3 and the user-specific generator 1 to continue to operate.

314164.ptd Page 13 200309429 V. Description of the invention (8). Moreover, as for the method of determining whether a short-circuit accident 13 occurs, for example, as shown in FIG. 1, a protective relay for feeding is provided for the circuit breaker 11 in advance. (Individual protection sensors and relays) 2 1. In the case of an accident at symbol 1 3, the accident was not detected by the directional short-circuit element of the protective relay 1 4, so it can be detected by the protective relay 2 1 for power feeding. The current element outputs a disconnection command to the circuit breaker 1 1 to open the circuit breaker 11. Moreover, in the first figure, Guwei only provided the protective relay 2 1 for power feeding in the circuit breaker 11, but this It is to simplify the diagram. In fact, a better way is to set a protective relay for power feeding on each circuit breaker. ® As above, when the short-circuit accidents 1 3 and 12 on the 3 side of the important load and the 6 side of the general load occur, the presence or absence of the directional short-circuit element is used to determine whether any short-circuit accident has occurred. The short-circuit accident on the 3 side of the important load When 13 occurs, the user-specific generator 1 is prevented from being damaged by not disconnecting the circuit breaker 7 for connection, and the important load 3 and the user-specific generator 1 can continue to operate. Moreover, in this embodiment, although the case where the protective relay 14 has a fixed short circuit element and a reverse power element will be described, it is not limited to this, and it may have only a directional short circuit element to detect an important load side Or a short-circuit accident on the general load side. ^ 3 Embodiments In the first and second embodiments described above, it is necessary to detect the overload condition of the user-specific generator and short-circuit accidents on the important load side at high speed, and output the disconnection / breaker signal to the disconnection breaker. An example of 7 will be explained. Without β, in this embodiment, a high-speed circuit breaker that can be disconnected half-cycle is used to connect the circuit breaker 7 to speed up the entire disconnection time of the switch-off system.

314164.ptd Page 14 200409429 V. Description of the invention (9) If the operating time of the protective relay 14 is set to 5ms (milliseconds) from the start of the abnormality when the fault occurs, the high-speed circuit breaker 7 The cut-off time is set to 11.4 ni s or less, and all the cut-off time (the time from the fault detection to the opening of the circuit breaker) is expressed by the sum of the cut-off time. Therefore, actions under 16.4 ms can be performed. The fault breaks off within one cycle. In this way, in the present embodiment, it is possible to make a break of less than 16.4 ms from the occurrence of a fault, so that the important load 3 connected can be protected. This is the fourth embodiment. In this embodiment, in addition to the directional short-circuit element and the reverse power element used for the protective relay 14 in the above-mentioned first and second embodiments, the deficiency of the voltage drop at the time of determining an accident is further added. The voltage element is in the arithmetic processing unit 20, which can suppress the influence of the voltage drop on the important load 3. Figure 4 shows the detection content and protection content of individual components. In the circuit shown in the first embodiment, in the case where the short-circuit accidents 13 and 12 occur on the side of the important load 3 and the side of the normal load 6, the undervoltage element operates regardless of the case. Therefore, it is not possible to determine on which load side a short-circuit accident occurs simply by the action of the undervoltage element. Therefore, in this embodiment, the short-circuit accident on the load side is detected by the detection of the under-voltage element, and the short-circuit accident on the load side is determined as which load is the important load side and the general load side by the detection of the directional short-circuit element. Side short circuit accident. Moreover, although it is possible to detect both the action of the under-voltage element and the action of the directional short-circuit element to determine which load side of the load the short-circuit accident occurred, however, the logic of the under-voltage element and the directional short-circuit element can also be obtained

314164.ptd Page 15 200409429 V. Description of the invention (ίο) and (A N D). ^ Moreover, the voltage drop detection time of the protection relay of the present invention reaches less than 3.5 ms from the start of the voltage drop, and it is combined with the high-speed circuit breaker break time of 11.4 ms shown in the third embodiment, which is all in this embodiment. The disconnection time is 14.9 ms or less. Because of this, in the present embodiment, it is possible to make a disconnection of -14. 9ms or less since the occurrence of the fault, so that the important load connected 3 can be protected. Moreover, in the above-mentioned first to fourth embodiments, although an example in which the values of the voltage three-phase and the current three-phase are input to the protective relay 14 is described, but, in this case, as for the voltage, since the voltage between lines is used, The voltage of the remaining TR phase can be obtained from the voltage of the RS phase and the ST phase, so it can be an input of two phases. In this case, the same effect is obtained. '[Industrial availability]-As mentioned above, the protective relay of the present invention is used as a high-speed detection device to connect commercial-side buses and user-specific power at the business office where the user-specific power generation equipment is maintained. Reverse power elements, directional short-circuit elements, and protective relays for disconnecting circuit breakers at connection points are useful.

314164.ptd Page 16 200409429 Brief Description of Drawings [Simplified Description of Drawings] Figure 1 is a circuit diagram showing an example of a circuit to which the protection relay of the present invention is applied. Fig. 2 is a structural diagram showing the internal structure of the protective relay of the present invention. Fig. 3 is an explanatory diagram showing a determination area of a reverse power element and a directional short-circuit element of a protective relay of the present invention. Fig. 4 is an explanatory diagram showing detection contents and protection contents of a reverse power element, a directional short-circuit element, and an undervoltage element of a protection relay of the present invention. Fig. 5 is a circuit diagram showing an example of a circuit to which a conventional protection relay is applied. 1 User-specific generator 3 Important load 5 Commercial-side busbar 7 Connection circuit breaker 9, 1 6 Converter (input mechanism) 1 1, 2 1 Feeder circuit breaker 15 Transformer 17 Amplifying circuit 19 (analog / digital) A / D converter 30 Judgment area 2 User-specific generator-side bus bar 4 Lead-in hole 6-Normal load 8, 1 5 Transformer (input mechanism) 1 0, 1 4 Protective relay 1 2, 1 3 Short circuit accident roadside electrical unit Filter at the device 6 8 0 IX 1X OA «

3l4l64.ptd Page 17

Claims (1)

200409429 6. Scope of patent application A protection relay is a system that is equipped with a circuit breaker for connection between the connection point of the commercial-side busbar connected to the general load and the important-load power-side busbar connected to the important load. Its characteristics It is equipped with: an input mechanism for inputting the voltage and power supply of the commercial-side bus respectively; a reverse power detection mechanism for detecting the reverse power outflow from the power supply-side bus for important loads to the commercial-side bus based on the values of the voltage and the current; And the first circuit breaker disconnection signal output mechanism 'outputs a circuit breaker disconnection signal for disconnecting the connection circuit breaker when the reverse power detection and detection mechanism detects the outflow of reverse power. 2. The protection relay according to item 1 of the scope of patent application, further comprising: a directional short-circuit detection mechanism that detects whether there is reactive power flowing out based on the voltage and the current value, and determines that a short-circuit accident has occurred on the general load side and Which of the above-mentioned important load sides; and the second circuit breaker disconnection signal output mechanism, in which the directional short-circuit detection mechanism determines that the short-circuit accident has occurred in the general load, and when it does, the output is used to open the connection circuit breaker The breaker disconnect signal. —A protection relay is a system equipped with a circuit breaker for connection at the connection point of the commercial side bus connected to a general load and the important load power side bus connected to an important load. It is characterized by: an input mechanism, Input the voltage and current of the commercial bus 314164.ptd Page 18, 200409429 VI. Patent Application Directional short-circuit detection mechanism, by detecting the presence or absence of reactive power flowing out according to the values of the above voltage and the above current, it is determined that the short-circuit accident detected by the above-mentioned under-voltage detection mechanism occurred Which one of the general load side and the important load side; and a circuit breaker disconnection signal output mechanism, which outputs to disconnect the connection open circuit when the directional short-circuit detection mechanism determines that the short-circuit accident occurs on the general load side Circuit breaker disconnection signal. 4. If the protection relay of the second or third item of the scope of patent application, further includes an under-voltage detection mechanism to detect that the voltage value of the commercial side bus is below a predetermined value based on the value of the voltage and the current. To determine which side of the general load side and the important load side the short-circuit accident occurred, the directional short-circuit detection mechanism detects whether there is reactive power flowing out based on the value of the voltage and the current, and uses the above-mentioned deficiency The voltage detection mechanism determines which of the short-circuit accident occurred on the general load side and the important load side. 5. If the protection relay of any one of claims 1 to 3 of the scope of patent application, wherein the above-mentioned connection circuit breaker is composed of a high-speed circuit breaker that can be cut off half-cycle; When the abnormality starts, the time will be less than 5 Ι s. When the disconnection time of the above-mentioned circuit breaker for connection is less than 1 1.4 ms, the total disconnection time will be less than 1 cycle since the failure occurred. 314164.ptd Page 19