JPS6031172B2 - Interconnection line power interruption detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interconnection line power interruption detection device for detecting when interconnection line power has become zero due to a cause in another system in a power system that performs power interchange between two systems. It is something.

Figure 1 shows the power system.

The area inside the diagonally shaded frame 1 is another power system, and the area outside the frame is the main system.
The shield disconnector 152R in the pond system is used to connect and disconnect the interconnection line with the main system, and many generator groups and load groups are connected (not shown) to the illustrated upper bus line BUS of 152R. . The power line disconnector 152 of this system has the same purpose as the power line disconnector 152R of the pond system, and is for connecting and disconnecting interconnection lines between systems. In addition, the generator G of this system is the generator and the disconnector 52
and is connected to the main system via the main transformer MT. Further, this system is connected to a load group L via a load transformer LT and a load shear disconnector 52F. Next, we will explain power interchange between this system and other systems.

The following four cases can be considered as power interchange methods. Case A: For the main system load L', the power of the generator G of the main system and the power shortage in the generator G is supplied from another system.

At this time, the shield breakers 152R, 152, 52, and 52F are all turned on. Case B: Power is supplied from the generator G of the main system to the main system load L', and the surplus power of the generator G is transferred to the pond system.

At this time, the shield breakers 152R, 152, 52, and 52F are all turned on.

Case C: While the generator G of the main system is stopped, power is supplied to the load L of the main system from another system.

At this time, the shield disconnectors 152R, 152, and 52F are turned on.
becomes. Case D: Power from the generator G of this system is supplied to another system, but no power is supplied to the load L of this system.

At this time, the sheath disconnectors 152R, 152, and 52 are turned on. In the above-mentioned power interchange state, if the shield disconnector 152R of the other system is tripped, in case A among the above cases A to D; the generator G is switched off because the load for which the power was interchanged becomes insufficient. As overload may occur, the turbine rotation speed may drop, and the turbine, generator, etc. may be in a dangerous state, so either increase the power generated by generator G or reduce the load on the load side L to a value commensurate with the output of generator G. The need arises.

In case B: The load that was being used for power interchange becomes surplus power, and the load on generator G becomes light.The turbine rotation speed increases, potentially putting the turbine, generator, etc. in a dangerous state, so the power generated by generator G is reduced. It becomes necessary to increase the load on the load side L to a value commensurate with the output of the generator G.

Case C: There is no effect on generator G.

Case D: Since the load on the generator G becomes irrelevant, the turbine rotational speed suddenly changes and increases, so it is necessary to immediately stop the turbine and generator or return them to the rated speed.

As described above, with the exception of case C, if a breakout switch in another system goes out and power cannot be exchanged, some kind of adjustment of the generator G or load L is required in this system.

Conventionally, the trip of the breaker 152R was this breaker 15.
Judgment is often made based on the whisker point output of 2R itself.

However, if the shield breaker 152R is located in a remote location other than the main system, a cable must be laid from the main system to the installation point of the shield breaker 152R in order to take out the contacts of the shield breaker. However, as the cable becomes longer, the cost increases and the line resistance of the cable increases, making it impossible to accurately detect whether the contacts are open or closed. Therefore, a transmission device is required to input the breaker contact to the main system.
Costs increase. In addition, when a transmission device is provided, costs increase due to higher reliability of the transmission device or multiplexing of transmission lines to achieve higher reliability. Even if the disconnector is not located far away, there may be cases where all the contacts of the disconnector 152R are used and the contacts cannot be made, or there are many equivalent disconnectors for the disconnector 152R, so each disconnector can be disconnected. If the contacts cannot be put together in one place, or if the disconnector 152R is in another power company's system, do not connect the contacts, and if the main system is affected by an abnormality in the pond system. There may be cases where the main system has no choice but to detect an abnormality in the pond system. In order to solve these problems, conventionally, zero detection of interconnection line power or current amount is performed, and when the interconnection line power is zero, the breaker 152R trips (however, the breaker 152R trips (however, breaker 152, 52, 5
However, interconnection line power is not unidirectional; it is always connected from other systems to the main system, and from the main system to the pond system. Because interconnection line power may temporarily drop to zero due to mutual accommodation, a conspiracy must be detected in this case.

In view of this point, the present invention, in a power system that is interconnected with the pond system, is capable of reducing interconnection line power input, disconnection, and disconnection trips provided in other systems to zero interconnection line power or zero current. It is an object of the present invention to provide an interconnection line power failure detection device that detects under conditions other than the grid frequency reference value and eliminates the need for connecting disconnection trip contacts from other systems.

An embodiment of the present invention will be described below with reference to the drawings.

First, the interconnection line power and frequency detection circuit will be explained with reference to FIG. In Figure 2, the area within frame 1 is another power system, and the others are this system. In the pond power system in frame 1, the generator group and the load group are connected to the bus BUS, and the interconnection line is connected, disconnected, and disconnected by 152.
Connected to R. Reference numeral 152 denotes an interconnection line entry/disconnection/disconnection switch provided in the main system, similar to the above-mentioned line/disconnection switch 152R.

The interconnection line is equipped with a current transformer CT and a potential transformer PT.
The current transformer CT secondary current i and the transformer PT secondary voltage V are input to the interconnection line power force detector 2, and the transformer PT secondary voltage is input to the frequency detector 3. The interconnection line power zero detector 2 detects when the interconnection line power is zero, and when zero is detected, the relay A operates. Frequency detector 3 also detects that the system frequency has deviated from the normal frequency change that occurs when disconnectors 152 and 152R are "on" and connected to other systems, and at this time relay B is activated. do. In addition, since the input V of the frequency detector 3 becomes 0 V when the generator G is stopped (the shield breaker 52 is "off") and the shield breaker 152 is "off" or the shield breaker 152R is "off", Detection relay B operates in the same state as the abnormal frequency drop. The generator G is a generator with constant output control, and is connected to the main system via the generator sheath disconnector 52 and the main transformer MT, and is connected to the main system via the load transformer LT and the load sheath disconnector 52F. The load group L' of this system is connected. Next, the relay sequence circuit will be explained with reference to FIG.

In the figure, contacts 152-1a, 152-2a, 152-3a are auxiliary contacts that close when the cutter 152 is turned on, and contacts 52-la, 52-3a are the auxiliary contacts that close when the cutter 152 is turned on. “
521b is an auxiliary contact that is closed when it is "on", and 521b is an auxiliary contact that is closed when it is "off". Contacts 52F-la and 52F-2a
is closed when the load and disconnector 52F is "on", and contact 5
2F-3b is an auxiliary contact that closes when "off". Relay C terminal disconnector 152 is “on”, generator terminal disconnector 52
is "on", and the load disconnector 52F is "off", power is transferred from generator G of the main system to the pond system, and when power is not being supplied to the main system load, it operates and output contact C-la Close.
Relay D and disconnector 1 52 are “on,” generator and generator disconnectors 52 are “off,” and load and disconnectors 52F are “on,” allowing power to be transferred from other systems to main system load L, and the main It operates when the generator in the system is stopped, and the output contact D-la is opened. In addition, the relay E terminal and disconnector 152 is “on”, and the generator terminal and disconnector 5
2 is "on", and the load disconnector 52F is "on", and power is supplied to the main system load L from both the other system and the main system generator G, or the main system generator G is connected to the main system load L and the main system generator G. It operates when power is supplied to the grid, and the output contact E-la is closed. Contact B
-la is a contact that is closed when relay B in FIG. 2 is operated, and contact A-la is a contact that is closed when relay A is operated. The relay FT is a time-limited relay, and when the relay FT operates and the contact FT-la opens, it holds itself, and the hold-return switch contact G-lb
It continues to be held until it is closed. Next, the operation of the present invention will be explained.

Changes in the system frequency when the pond disconnectors 152 and 152R are turned on and connected to other systems are connected to the bus line BUS of the pond system, regardless of load changes in other systems or load changes in the main system. During the operation of the generator group and the main system, the generator G of the main system controls the frequency to be the reference frequency. Therefore, since the frequency change caused by the load change is controlled to be immediately suppressed, the amount of frequency fluctuation is approximately within the predicted range. However, if the breaker 152 or 152R breaks and the main system becomes an isolated system, the frequency change caused by the load change of the main system load L will be controlled only by the generator G of the main system. Generally, the amount of frequency fluctuation is larger than when connected to other systems. In addition, in a state where power was being exchanged with other systems, disconnection switch 152R or 1
52 is cut off instantaneously, the amount of power that was being exchanged becomes insufficient or excessive for the main system, so the frequency suddenly increases or decreases by the amount corresponding to this excess or shortage, and then the frequency control of generator G is changed. This excess or deficiency is controlled according to the gain and time constant. Also, even if other systems and the main system are connected, there may be a state in which the interconnection line power is zero, but if a change in the main system load L occurs, the frequency will change, so the output of the main system's generator G will change. As the load changes, the interconnection line power also changes to compensate for the load change, but if it is not interconnected with other systems, the interconnection line power continues to be zero. Therefore, in the present invention, the interconnection line power zero detector 2 detects when the interconnection line power becomes zero due to the disconnection of other systems and the interconnection line power becoming zero, and the relay A is activated.

In addition, the range of change in system frequency fluctuation caused by this system becoming an independent system exceeds the amount of system frequency fluctuation when it is connected to other systems, and the water turbine generator G of this system is operating stably. Frequency detector 3
is detected and relay B is activated. Here, relay C
, D, and E represent the states of the three cases of the shield breakers 152, 52, and 52F in this system, and are similar to the three cases (cases A or B, C, and D) explained in the prior art. .

The reason for dividing the cases in this way is that the purpose of the present invention is to detect interconnection line power interruptions due to causes in other systems, so even if the condition of a disconnector in the main system changes, the interconnection line power may become zero. Therefore, each case is locked in order to prevent detection of fraud. That is, in the case where generator G is in operation, relay C or relay E operates and contact C-la or 8-1a is closed.
In this state, if another system is connected or the disconnector is turned off, the interconnection line power becomes zero, relay A operates and contact A-la closes, and at the same time the frequency exceeds the set range, so relay B operates. Since the contact B-la is closed, the time-limited operation relay FT starts counting the time.

If the frequency is not suppressed within the set range during the time count period, relay F is activated by contact FT-la of relay FT.
T is self-preserving. This self-holding continues until the operator operates the holding return switch G-16. Depending on the operation of the relay FT, it is determined whether other systems or disconnectors are "off". The time setting of the time-limited operation relay FT is set to the time required for control to pull back the frequency fluctuation when the other system or disconnector is "on". In addition, in the above, if the interconnection line power amount before the other system or disconnector is "off" is small,
It is possible that the frequency fluctuation does not exceed the set width. In this case, it is not possible to immediately detect the disconnection of the pond system or disconnection, but there is no particular problem because the frequency at this time is within the range in which the water turbine generator G can operate stably. However, when the frequency exceeds the set range due to a change in the load L of this system, it can be determined that the pond system or disconnector has tripped. In addition, in the case where relay ○ is operating, that is, when the main system generator is stopped and power is being supplied to the main system's load L from another system, there is no change in frequency due to the interconnection line power disconnection condition. Since it is also possible to determine whether the relay is connected to another system or whether the circuit is disconnected, frequency conditions are not included in the operating conditions of the relay FT. still,
In the above embodiment, interconnection line power interruption is detected by the amount of electric power, but it may be detected by the amount of current.

Further, although the interconnection line power is observed on the generator side of the shield disconnector 152, it is also possible to detect the interconnection line power at a point where the interconnection line power can be detected, for example, in the darkness of the shield disconnector 152 and 152R. According to the present invention described above, it is possible to detect within the main system that a pond system or disconnector is "off", so there is no problem with line resistance due to cable installation to other systems or disconnectors. Accordingly, it is possible to provide an interconnection line power interruption detection device that can suppress an increase in cost due to the installation of transmission equipment.

[Brief explanation of the drawing]

Figure 1 is a single line diagram showing an interconnected power system, Figures 2 and 3
The figures are a single-line system diagram and a control circuit diagram illustrating an embodiment of the present invention. 1... Other system, 2... Interconnection line power zero detector, 3... Frequency detector, 152R, 152
...Interconnection line disconnector, 52...Generator disconnector, 52F...Load disconnector, G...
- Generator, A, B, C, D. E: Auxiliary relay, FT: Time-limited operation relay. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 In a power system where power is interchanged between each other, a system is equipped with a zero interconnection power or current detector and a system frequency detector that operate when interconnection line power or current is zero, and An interconnection line power failure detection device that detects when a disconnector in another system is disconnected due to a zero condition and a condition in which the system frequency exceeds the frequency change range of the system frequency when interconnected with another system.