JPS58119735A - Power interlocking device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power interconnection device that transfers power between an AC system and a power conversion device.

Generally, the power conversion system block diagram of the power grid (hereinafter referred to as the grid) and the power interconnection device that transfers power is shown in the first diagram.
As shown in FIG. In Figure 1, (1) is a power conversion device, (2) is a connection device, (31 is a system, (4) (
May is a breaker that cuts off the connection between the power converter (1) and the grid (3).

In the above configuration, power is normally transferred between the power conversion device (1) and the system (3) via the connection device +2). At this time, if the circuit breaker (4) interrupts the connection between the two, power cannot be exchanged, and the original purpose of the conversion system is lost. Therefore, the power converter (1) is stopped by detecting that the breaker (4) is in the cutoff state, for example, by using an auxiliary contact of the breaker (4).

However, as shown in Figure 2, in a general power system, a large number of circuit breakers (4) (5) are installed very far away from the power converter (1), and each It is almost impossible to stop the power converter (1) using the auxiliary contacts of the device. Therefore, there has been no effective means for directly detecting that the voltage on the grid side has become non-voltage during normal operation of the power conversion system. For example, even if the breaker (6) in Fig. 2 is in the cutoff state,
The output voltage of the power converter (1) is applied to the system from the power converter (11) to the breaker (5), and there is a dangerous situation where ``voltage is still applied even if the breaker is opened.'' This was a major drawback of conventional systems.

The present invention has been made to solve the above-mentioned drawbacks.
The normal automatic control loop of the power converter that transfers power to and from the grid is used to detect when the voltage on the grid side has become non-voltage (hereinafter referred to as reverse pressure detection), and the power converter is immediately activated. Provided is a power interconnection device that can improve safety by stopping or cutting off between a power converter and a power grid.

The figures will be explained below. In FIG. 8 and FIG. 4, (6) is a breaker that can be cut off by a cutoff signal;
Sl is the output voltage signal of the power conversion device (1), S2 is the system voltage signal supplied by the system (3), (7) is the power conversion unit consisting of a semiconductor element such as a thyristor GTO or a transistor, and (8) is the system voltage signal supplied by the system (3). Control unit of conversion unit (7), (9)
is the first detection unit that detects the output voltage signal S1, and (g) is the system voltage signal S! The second detection section detects 0, and 0 is automatic which causes the output of the first detection section (9) (resultingly St) to follow the output of the second detection section (to) (resultingly S2) The control circuit and the song are output from the first detection section (9) (as a result, Sl
) is within the allowable value with respect to the specified value K. In this way, the output voltage signal S1 is an independent system configured to follow the system voltage signal S2.

Next, the operation will be explained. In Figure 4, when the conversion system is in normal operation, the automatic control circuit section is (F)
The feedback circuit is configured so that S1 follows (2) (S1 follows 52), and operates stably.

For example, a case where the operation S,=S, is performed will be explained. Both detection parts (9) (1G transfer function 02
and Gl are equal, so F=R and stable. If 82 increases by Δs2 for some reason, at that moment R increases by ΔR, and the input to the automatic control circuit (b) increases by ΔR. As a result, the output of the automatic control circuit aυ increases and is controlled so that 51=B+ΔB. S
Even when l changes by ΔS1, stable operation is achieved by the same operation. This is because the reactor (2) exists between Sl and 32, and furthermore, Sl and 8
This is because they can take independent values without interfering with each other. In other words, by exchanging active power and reactive power between Sl and 82 via the connection device (2), Sl and 82 can take independent values.

However, when the voltage supplied by the grid becomes non-voltage, Sl
It becomes impossible to exchange power between 82 and 82, and inevitably S*
= becomes Sz.

This means that if R″qF occurs due to a disturbance, etc., the automatic control loop will not operate normally and the control system will diverge as 51=82.In other words, if R)F In the case of , the whole system operates so that sl increases in an attempt to increase F, but since there is no power exchange between sl and 52, 52 also increases by the amount that sl increases, and as a result, This results in an unstable system in which disturbances are not suppressed.

Therefore, since the value of F that can be taken in a normal case is known in advance, the back pressure can be detected by comparing this value with the normal value on the comparison/discriminator side. However, if there is no disturbance at all, the value of F may not deviate significantly from K, although it is unstable.

FIG. 5 shows another embodiment in which ε is added to force the values of St and Sl to have a difference. When ε causes a difference in voltage magnitude, reactive power is exchanged between Sl and 82 via the connecting device (2), and when e causes a difference in voltage phase,
Active power is exchanged between Sl and S via the connecting device (2). Therefore, when the grid becomes voltageless, S
Although power is exchanged between 1 and 82, the automatic control system diverges and a cutoff signal is output.

In other words, the automatic control system in FIGS. 4 and 6 may be a voltage control system that controls the magnitude of voltage, a phase control system that controls the phase of voltage, or a power control system that handles both. By doing so, it is possible to detect no-voltage in the grid (reverse pressure detection).
can be easily carried out. Incidentally, in the case of a phase control system, a PLL circuit is generally used in many cases. this is,
This takes advantage of the fact that the converter, which originally operates stably as a self-limiting system, changes to a self-limiting system and becomes unstable due to no voltage in the grid.

The present invention can be applied to all power interconnection devices that are connected to the grid and exchange active power and reactive power, such as static non-active power generators (abbreviated as SVG
), and when applied to the power conversion device of a solar power generation system, it exhibits great effects.

However, in Figs. 4 and 5, even if a cutoff signal is generated and the converter (l) is stopped or the breaker (6) is tripped, it may be difficult to say that the back pressure has been detected. . For example, it may be due to a failure of the converter (1) itself or a temporary disturbance on the grid side. Therefore, as shown in FIG.
The AND circuit (b) detects both that the output of the detection section (2) is gone and that the cutoff signal is output.
If it is determined by ζ, it is possible to perform a complete back pressure protection operation. 4 is a display means for back pressure protection operation.

Note that even if the reactor (2) in the figure is a transformer with a built-in reactance, the operation is exactly the same.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing a conventional power interconnection device, FIGS. 8 and 4 are block diagrams showing a power interconnection device according to the present invention, and FIGS. 6 and 6 are block diagrams showing a power interconnection device according to the present invention. FIG. 3 is a block diagram showing another embodiment. In the figure, (l) is a power conversion device, (2) is a connection device, +37 is a power system, (4) (5) is a circuit breaker with auxiliary contacts, (6) is a trippable circuit breaker, (9 )
QQ is a detection unit for the output voltage signal of the power converter, and QQ is a detection unit for the system voltage signal supplied by the power system. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (7)

[Claims] (1) In devices that connect an AC power system and a power conversion device via a connection device to exchange active power and reactive power, it is possible to detect when the voltage supplied from the power system has become non-voltage. A power interconnection device configured to detect with a detection device and cut off connection between the power conversion device and the power grid. (2) The power interconnection device according to claim 1, wherein the connection device is an AC reactor. (3) The power interconnection device according to claim 1, wherein the connecting device is a transformer having a built-in beam actance. (4) an automatic control circuit in which the detection device uses a voltage signal supplied from the power system as a reference input signal and a voltage signal corresponding to the output voltage of the power conversion device as a feedback signal;
9. The power interconnection device according to claim 1, further comprising a circuit for detecting that the voltage signal is outside a specified value. (5) The power interconnection device according to claim 4, wherein the automatic control circuit controls voltage. (6) The power interconnection device according to claim 4, wherein the automatic control circuit performs phase (frequency) control. (7) The power interconnection device according to claim 4, wherein the automatic control circuit is an active power control circuit or a reactive power control circuit that simultaneously controls voltage and phase.