Circuit breaker control device and circuit breaker control method

Abstract

To provide a breaker control apparatus that can cope with an increase in fault current simply and inexpensively.SOLUTION: The breaker control apparatus includes: an operation unit 31 that detects an occurrence of a system accident including a short-circuit accident of an AC power system and actuates breakers 21, 22, and 23; and a time limit unit 32 that, in a case where an accident current including a DC component in the system accident exceeds a rating capacity of the breakers 21, 22, and 23, defers actuation by the operation unit 31 until the DC component of the accident current decreases so that the accident current becomes the rating capacity or lower of the breakers 21, 22, and 23.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a circuit breaker control device and a circuit breaker control method for controlling the operation of a circuit breaker. [Background technology]

[0002] If a short circuit or ground fault occurs in a power system and the fault current exceeds the rated interrupting current and rated capacity of the circuit breaker, it may become unable to interrupt the circuit. For this reason, when it is expected that the fault current will exceed the rated capacity of a circuit breaker as the capacity of the power system increases, measures have traditionally been taken to reduce the fault current and short circuit capacity by replacing the circuit breaker with a larger capacity or special specification circuit breaker or by switching the power system (for example, by cutting the loop).

[0003] However, replacing a circuit breaker with a larger capacity or special specification not only increases the cost of the circuit breaker itself and the construction costs, but also lengthens the construction period, making system operation difficult. Furthermore, switching the power system can complicate system operation and reduce system reliability. Meanwhile, there is a known technology that can shorten the construction period by avoiding the shutdown of the bus when replacing a circuit breaker (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-052149 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since a power system is equipped with many circuit breakers, if it is assumed that the fault current will exceed the rated capacity of the circuit breakers, replacing all the circuit breakers or switching the power system would not only be extremely costly, but would also extend the construction period and complicate system operation, which could significantly reduce system reliability. Therefore, a simple, low-cost solution that can deal with increases in fault current has been sought.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a circuit breaker control device and a circuit breaker control method that are simple and inexpensive and can cope with an increase in fault current. [Means for solving the problem]

[0007] In order to solve the above problem, the invention of claim 1 comprises a fault detection means for detecting the occurrence of a system fault including a short circuit fault in an AC power system, an operation means for operating a circuit breaker when the occurrence of the system fault is detected by the fault detection means, and a fault current including a DC component in the system fault is detected by the circuit breaker. Rated Breaking Current When the DC component of the fault current exceeds Rated Breaking Current and a waiting means for waiting for the operation by the operating means until The fault detection means and the operation means are configured by a protective relay, and the standby means is configured by an external timer. The circuit breaker control device is characterized by the above.

[0009] Claim 2 The invention of With protective relay a fault detection step of detecting an occurrence of a system fault including a short circuit fault in an AC power system; and when the occurrence of the system fault is detected in the fault detection step, The protective relay and an operating step of operating a circuit breaker, wherein the operating step is performed by determining whether a fault current including a DC component in the system fault is greater than the threshold of the circuit breaker. Rated Breaking Current If it exceeds An external timer The DC component of the fault current is reduced and the fault current is Rated Breaking Current and then actuating the circuit breaker after waiting until the voltage reaches or exceeds the threshold voltage. [Effects of the Invention]

[0010] Claim 1 and 2 According to the invention described in the above, the fault current in the event of a system fault is Rated Breaking Current Even if the fault current exceeds the limit, the DC component of the fault current will decrease and the fault current will Rated Breaking Current The circuit breaker will trip and trip until the fault current increases to the level below the Rated Breaking Current Even if the fault current exceeds the limit of the circuit breaker, the circuit breaker can still function properly, and there is no need to replace the circuit breaker with a larger capacity or special specification one or to switch the power system. Rated Breaking Current Since it is only necessary to wait until the current falls below this level, it is possible to respond to increases in fault current (increased capacity of the power system) easily and at low cost.

[0011] Claim 1 and In the invention of 2, the fault detection means and operation means are configured in a protective relay, so it is possible to easily, simply, and at low cost construct this circuit breaker control device using a ready-made / existing protective relay. Also, because the standby means is configured in an external timer, it is possible to easily, simply, and at low cost construct this circuit breaker control device by simply attaching an external timer (retrofitting). In other words, there is no need to replace the protection panel / control panel of the protective relay, so it is possible to construct this circuit breaker control device easily, simply, and at low cost. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a part of a power system including a circuit breaker control device according to an embodiment of the present invention; [Figure 2] 2 is a schematic diagram showing a protective relay constituting the circuit breaker control device of FIG. 1. FIG. [Figure 3] This is a conceptual diagram showing the change over time in fault current and its DC component. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be described below based on the illustrated embodiments.

[0014] Fig. 1 is a diagram showing a part of a power system including circuit breaker control devices 3, 4, and 5 according to an embodiment of the present invention. These circuit breaker control devices 3, 4, and 5 are devices for controlling circuit breakers 21, 22, and 23, and as will be described later, are mainly composed of ready-made, existing protective relays. In other words, the circuit breaker control devices 3, 4, and 5 are configured by utilizing protective relays that are already installed and in operation.

[0015] Here, in this embodiment, a part of the following power system will be described as an example, but the circuit breaker control devices 3, 4, and 5 can be applied to any power system.

[0016] That is, a bus circuit breaker 21 is provided between the bus bars L0, and a bus circuit breaker controller 3 is provided for controlling the opening and closing of this bus circuit breaker 21. Two house transformers 6 are connected to the bus bar L0 via transformer circuit breakers 22, and a transformer circuit breaker controller 4 is provided for controlling the opening and closing of the transformer circuit breakers 22. Two shunt reactors (branch reactors) 7 are connected to the bus bar L0 via one shunt circuit breaker 23, and a shunt circuit breaker controller 5 is provided for controlling the opening and closing of the shunt circuit breaker 23.

[0017] The bus circuit breaker control device 3 is composed of a bus protective relay BP (protective relay), while the transformer circuit breaker control device 4 and shunt circuit breaker control device 5 are composed of an overcurrent relay OC (short-circuit relay protective relay). In this way, all of the circuit breaker control devices 3, 4, 5 are composed of protective relays, and such protective relays have the same configuration as existing, pre-fabricated protective relays, and as shown in Figure 2, they mainly comprise a calculation unit (fault detection means, operation means) 31 and a time limit unit (standby means) 32, but as will be described later, the time limit unit 32 has a different configuration from existing, pre-fabricated protective relays.

[0018] That is, when the calculation unit 31 detects the occurrence of a system fault, including a short-circuit fault in the AC power system, it operates and trips the circuit breakers 21, 22, and 23. Specifically, the calculation unit 31 takes in the current value I1 at its own end and the current I2 at the other end measured by the ammeter 33, performs predetermined relay calculation processing, and outputs a trip signal TS when it detects an abnormality or system fault in the transmission line (including the bus bar L0). Then, when this trip signal TS is input to the circuit breakers 21, 22, and 23, the circuit breakers 21, 22, and 23 operate and trip.

[0019] Furthermore, the timing unit 32 is a timer that adjusts and limits the input timing (tripping timing) of the trip signal TS from the calculation unit 31 to the circuit breakers 21, 22, and 23. In this embodiment, mainly when a fault current including a DC component in a system fault exceeds the rated capacity of the circuit breakers 21, 22, and 23, the input of the trip signal TS (operation by the calculation unit 31) is put on hold until the DC component of the fault current decreases and the fault current becomes equal to or less than the rated capacity.

[0020] In other words, fault currents generally contain DC components in addition to AC components, and if the fault current exceeds the rated interrupting current and rated capacity of the circuit breakers 21, 22, and 23 (or if the DC component is large), the circuit breakers 21, 22, and 23 may not be able to properly interrupt the current, or their interrupting performance may be reduced. On the other hand, the DC component of the fault current decays over time, as shown in Figure 3. For this reason, the trip signal TS is input to the circuit breakers 21, 22, and 23 after the DC component of the fault current has decreased and the fault current is equal to or less than the rated capacity of the circuit breakers 21, 22, and 23 (until proper interruption is possible).

[0021] Specifically, the fault current value including the DC component immediately after the occurrence of a system fault is calculated, measured, etc. in advance, and it is confirmed whether or not it exceeds the rated capacity of the circuit breakers 21, 22, and 23. In this embodiment, it is assumed that the fault current value immediately after the occurrence of the fault exceeds the rated capacity of the circuit breakers 21, 22, and 23.

[0022] Then, the fault current value and DC component attenuation characteristics (changes over time) in the event of a system fault are calculated and measured, and the waiting time after the occurrence of the system fault is calculated and determined so that the fault current value falls below the rated capacity of circuit breakers 21, 22, and 23 and proper interruption can be performed. The waiting time is calculated and determined so that an excessively long waiting time does not cause problems in system operation or accident response (for example, expansion of the power outage area). Furthermore, the waiting time is calculated and determined taking into consideration that in systems far from thermal power plants and generators, the DC component attenuates more quickly over time.

[0023] In this way, the standby time is calculated and determined for each of the circuit breakers 21, 22, and 23. Then, the timing unit 32 waits for the standby time, and then the trip signal TS is input to the circuit breakers 21, 22, and 23.

[0024] Here, the ready-made / existing busbar protective relay that constitutes the busbar circuit breaker control device 3 is capable of changing the time limit, so by adjusting the time limit of the time limit unit 32 to the above-mentioned waiting time by changing the setting, the trip signal TS is input to the busbar circuit breaker 21 after waiting for the waiting time after the occurrence of a system fault.

[0025] Furthermore, the ready-made / existing overcurrent relay that constitutes the transformer circuit breaker control device 4 is equipped with an instantaneous element that instantly inputs a trip signal TS to the transformer circuit breaker 22 when a system fault occurs, and a time element that inputs the trip signal TS to the transformer circuit breaker 22 a predetermined time after the system fault occurs. Because the predetermined time of the time element is equal to or longer than the above-mentioned standby time, the instantaneous element is locked (prevented from tripping instantly) by changing the setting, so that the trip signal TS is input to the transformer circuit breaker 22 after waiting for the standby time or longer from the occurrence of the system fault, using only the time element of the time limit unit 32.

[0026] On the other hand, the off-the-shelf / existing overcurrent relay 51 that constitutes the shunt circuit breaker control device 5 has an instantaneous element and a time limit element, just like the transformer circuit breaker control device 4, but is designed so that the instantaneous element cannot be locked by changing the setting. For this reason, instead of (in addition to) the time limit unit 32, an external timer 52 is arranged between the overcurrent relay 51 and the shunt circuit breaker 23. The time limit of this external timer 52 is set to the above-mentioned standby time, and the trip signal TS output from the overcurrent relay 51 waits for the standby time before being input to the shunt circuit breaker 23.

[0027] In this way, the circuit breaker control device 3 for the bus is configured by changing the settings of an existing, pre-made busbar protective relay, and similarly, the circuit breaker control device 4 for the transformer is configured by changing the settings of an existing, pre-made overcurrent relay. Meanwhile, the circuit breaker control device 5 for the shunt is configured by providing an external timer 52 to an existing, pre-made overcurrent relay 51. In other words, the circuit breaker control devices 3, 4, and 5 are configured by utilizing existing, pre-made protective relays.

[0028] Next, the operation of the circuit breaker control devices 3, 4, and 5 configured as above, and a circuit breaker control method using the circuit breaker control devices 3, 4, and 5 will be described.

[0029] First, when a system fault including a short-circuit fault occurs in an AC power system, the calculation unit 31 of each of the circuit breaker control devices 3, 4, and 5 detects the occurrence of the system fault (fault detection step). Then, each calculation unit 31 outputs a trip signal TS to the circuit breakers 21, 22, and 23 via the timing unit 32 or the external timer 52, thereby operating and tripping the circuit breakers 21, 22, and 23 (operation step). At this time, the fault current value immediately after the fault occurs exceeds the rated capacity of the circuit breakers 21, 22, and 23, so the timing unit 32 of each of the circuit breaker control devices 3 and 4 and the external timer 52 of the circuit breaker control device 5 wait until the DC component of the fault current decreases and the fault current value becomes equal to or less than the rated capacity, and then inputs the trip signal TS to the circuit breakers 21, 22, and 23, thereby operating the circuit breakers 21, 22, and 23.

[0030] As described above, according to the circuit breaker control devices 3, 4, 5 and circuit breaker control method, even if the fault current during a system fault exceeds the rated capacity of the circuit breakers 21, 22, 23, the circuit breakers 21, 22, 23 will not operate and trip until the DC component of the fault current decreases and the fault current falls below the rated capacity of the circuit breakers 21, 22, 23. In other words, even if the fault current increases and exceeds the rated capacity of the circuit breakers 21, 22, 23, the circuit breakers 21, 22, 23 can be operated properly, eliminating the need to replace the circuit breakers 21, 22, 23 with larger-capacity or special-spec circuit breakers or to switch the power system. Moreover, because it is only necessary to wait until the fault current falls below the rated capacity of the circuit breakers 21, 22, 23, it becomes possible to respond to an increase in fault current (an increase in the capacity of the power system) simply and at low cost.

[0031] In addition, because the fault detection means and operation means are configured in protective relays, it is possible to easily, simply, and at low cost construct the circuit breaker control devices 3, 4, and 5 using existing, pre-fabricated protective relays. In particular, the circuit breaker control device 3 for busbars can be constructed simply by changing the settings of an existing, pre-fabricated busbar protective relay, and similarly, the circuit breaker control device 4 for transformers can be constructed simply by changing the settings of an existing, pre-fabricated overcurrent relay.

[0032] Meanwhile, a shunt circuit breaker control device 5 can be constructed simply by providing an external timer 52 to a ready-made, existing overcurrent relay 51. In other words, since the standby means is configured with the external timer 52, a shunt circuit breaker control device 5 can be constructed easily, simply, and at low cost simply by attaching an external timer (retrofitting). Therefore, there is no need to replace the protection panel or control panel of the overcurrent relay 51, and so construction can be done easily, simply, and at low cost.

[0033] In this way, for example, if circuit breakers 21, 22, and 23 were to be replaced with larger capacity, specially specified ones, the cost would be several hundred million yen and the construction period would be over twenty months, whereas with the present circuit breaker control devices 3, 4, and 5 and present circuit breaker control method that utilize existing protective relays, the cost can be reduced to several million yen and the construction period to around ten months.

[0034] Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and design changes within the scope of the present invention are also included. For example, in the above embodiment, the shunt circuit breaker control device 5 is configured by providing an external timer 52 to an existing, pre-fabricated overcurrent relay 51. However, if the instantaneous element can be locked by changing the setting of the existing, pre-fabricated overcurrent relay 51, the shunt circuit breaker control device 5 may be configured by locking the instantaneous element. In other words, it is sufficient to utilize the functions of existing, pre-fabricated protective relays as much as possible and wait for the above-mentioned waiting time before opening the shunt circuit breaker 23. [Explanation of symbols]

[0035] 21 Busbar circuit breaker 22 Transformer circuit breaker 23 Shunt circuit breaker 3. Circuit breaker control device for busbars (protective relay device) 31 Calculation unit (accident detection means, operation means) 32 Time limit section (standby means) 4 Circuit breaker control devices for transformers (protective relay devices) 5 Circuit breaker control devices for shunts 51 Overcurrent relay device (protective relay device) 52 External Timer 6. House Trance 7 Shunt reactor TS Trip Signal

Claims

1. a fault detection means for detecting the occurrence of a system fault including a short circuit fault in an AC power system; an operating means for operating a circuit breaker when the occurrence of the system fault is detected by the fault detection means; and a standby means for causing the operating means to wait until the DC component of the fault current decreases and the fault current becomes equal to or less than the rated breaking current when the fault current including the DC component in the system fault exceeds the rated breaking current of the circuit breaker, The fault detection means and the operation means are configured as protective relays, The waiting means is constituted by an external timer. A circuit breaker control device characterized by:

2. A fault detection step of detecting the occurrence of a system fault including a short circuit fault in an AC power system by a protective relay device; an operation step of operating a circuit breaker by the protective relay when the occurrence of the system fault is detected in the fault detection step; and when a fault current including a DC component in the system fault exceeds a rated breaking current of the circuit breaker, the activation step waits by an external timer until the DC component of the fault current decreases and the fault current becomes equal to or less than the rated breaking current, and then activates the circuit breaker. A circuit breaker control method comprising:

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