JPH0245421B2 - RENKEISOCHI - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention connects two different power lines using thyristors, and when an accident occurs on one of them, immediately stops the connection or performs current limiting control. Related to grid interconnection equipment.

[Conventional technology]

FIG. 1 is a connection diagram showing the configuration of a conventional interconnection device.

In FIG. 1, numeral 1 is a interconnection device that interconnects different power systems 2 and 3, and 11 to 16 are thyristor valves. Moreover, 21 to 23 are series reactors having values selected so as not to impair the interconnection effect, and suppress the peak value of the fault current.
Further, 31 to 33 are current transformers for detecting grid-connected current, and 4 is an output current signal 8 of the current transformers 31 to 33.
This is a current value discriminator that determines the current level based on the current value, and generates an accident detection signal 7 when the interconnection current value is equal to or higher than a specified value. 5 is a gate signal generator;
6 is supplied to the gates of thyristor valves 11-16.

In a normal interconnected state, the voltages and phases of systems 2 and 3 are almost the same. Further, the gate signal generator 5 always generates the gate signal 6, and the thyristor valves 11 to 16 always generate the thyristor valves 11, 12; 13, 1 corresponding to each phase.
4; One of each pair of 15 and 16 is conductive. In the end, grids 2 and 3 are freely interconnected only through the impedance of reactors 21 to 23, but since the voltage and phase difference between grids 2 and 3 are not large, the interconnection current is below the specified value. .

Next, consider the case where a ground fault or short circuit accident occurs in the transmission line in grid 3.
Since the voltage of the system 2 decreases, a large voltage difference occurs between the system 2 and system 3, and the fault current flows from system 2 to system 3 via the interconnection device 1. This means system 3
In addition to increasing the fault current in the interconnection device 1, the healthy grid 2 will also be involved in the accident. Therefore, immediately gate block or phase control the thyristor valves 11 to 16 to prevent the current flowing through the interconnection device 1. It is necessary to suppress fault current. In FIG. 1, the discriminator 4 determines that the interconnection current signal 8 detected via the current transformers 31 to 33 has increased beyond the specified value, generates the fault detection signal 7, and generates the gate pulse generator 5. The fault current flowing through the grid interconnection device 1 is suppressed by stopping or controlling the phase of the gate signal 6 generated from the grid.

By the way, in conventional devices that determine the occurrence of a fault based on the magnitude of the interconnection current, the fault current is suppressed immediately after the occurrence of the accident, so recovery from the fault cannot be determined from the interconnection current. In order to restore normal interconnection after an accident is restored, a separate means of knowing whether the fault has been restored is required, and since power system circuits are generally inductive, fault current flowing through the interconnection equipment after an accident has occurred is necessary. It took some time for the value to exceed the specified value, which caused problems such as a delay in accident detection.

[Summary of the invention]

The present invention solves the above problems, and provides a grid interconnection device equipped with an accident detector that quickly and accurately determines the occurrence and recovery of an accident by detecting the interconnection voltage. With the goal.

[Embodiments of the invention]

An embodiment of the invention is shown in FIG. In the figure,
41 to 43 are voltage transformers for measuring the interconnection voltage of the interconnection device, and generate an inter-terminal voltage signal 10. Reference numeral 9 represents a voltage value discriminator, which emits an accident detection signal 7. Other items with the same symbols as in Figure 1 are shown in Figure 1.
This indicates that it is the same as the one shown in the figure.

In a normal interconnection state, as in FIG. 1, the voltages and phases of the systems 2 and 3 are almost the same, and the gate signal generator 5 always generates the gate signal 6 and the thyristor valves 11, 1
One of the pairs 2; 13, 14; and 15, 16 is always in a conductive state. In this state, the interconnection current is below the specified value, the inter-terminal voltage signal 10 of each voltage transformer 41 to 43 is small, and the fault detection signal 7 is not generated.

Next, if we consider the case where a ground fault or short circuit accident occurs in the transmission line in grid 3, immediately after the fault occurs, the voltage of each phase of grid 3 or the voltage of a specific phase decreases, and the voltage transformer 41 Any one of the .about.43 output voltages increases instantaneously at least.
If this increased voltage value is greater than or equal to the specified value, the voltage value discriminator 9 transmits the accident detection signal 7 to the gate pulse generator 5 in response to the voltage value becoming greater than or equal to the specified value.
By stopping or controlling the phase of the gate signal emitted from the gate pulse generator 5,
The fault current flowing through the interconnection device 1 is suppressed. Since such changes in the output voltages of the voltage transformers 41 to 43 occur simultaneously with the occurrence of an accident, the time required for fault detection is extremely short.

Next, considering the case where the fault is removed, the voltage of grid 3 will be restored at the same time as the fault is restored, so the output voltage of each voltage transformer 41 to 43 will return to the same small value as before the fault, and this voltage will become the specified voltage. When the value falls below this value, the accident detection signal 7 is stopped and the gate signal 6 is returned to the state before the accident occurred. This allows the system to automatically return to normal interconnection status after recovery from an accident.

The voltage value signal discriminator, which constitutes the main part of the present invention, may be a generally well-known comparator, or may be configured by software using a microcomputer.

Moreover, not only a voltage transformer but also a capacitor voltage divider may be used to detect the voltage between terminals.

Furthermore, although the embodiment has shown the case of interconnection between two different voltage systems, the present invention can also be applied to bus interconnection within the same system.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to suppress the fault current flowing through the interconnection device immediately after the occurrence of an accident, and there is an effect that normal interconnection can be performed immediately after the fault is removed.

[Brief explanation of the drawing]

Figure 1 is a connection diagram showing the configuration of a conventional interconnection device.
FIG. 2 is a connection diagram showing the configuration of a grid interconnection device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Grid connection device, 2, 3... Power system, 4... Current value discriminator, 5... Gate pulse generator, 9... Voltage value discriminator, 11-16... Thyristor valve, 21-2
3...Series reactor, 31-33...Current transformer,
41-43...Voltage transformer. In addition, in the figures, the same reference numerals indicate the same parts.

Claims (1)

[Claims] 1 In an interconnection device that interconnects two different power lines and is equipped with a thyristor that is controlled to immediately suppress the current flowing between both power lines when an accident occurs on either power line, A voltage value discriminator detects when the voltage between both terminals detected through the transformer connected to the A gate pulse generator that supplies gate pulses that are controlled to flow.