JPH0731301Y2 - Controller for reactive power compensator - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a reactive power compensator for the purpose of countermeasures against voltage flicker generated from a fluctuating load, and has a large capacity of a capacitor equipment for power factor improvement and harmonic absorption. Therefore, the present invention relates to a control device of a reactive power compensator capable of suppressing an increase in bus voltage when the variable load becomes light or no load.

[Prior Art] A static var compensator (hereinafter referred to as SVC device) using a thyristor control reactor (hereinafter referred to as TCR) system is used as a countermeasure against voltage flicker caused by a reactive power load such as an electric furnace that causes a sudden change. It is used.
Hereinafter, a conventional SVC device will be described with reference to FIG.

Reference numeral 1 is a power source, 2 is a power source impedance, a system bus 3 is connected to the power source 1, a variable load 4 such as an electric furnace is connected to the system bus 3, and a capacitor 21 and a series reactor 22 are shown. It is assumed that such a capacitor equipment 20 is connected.

10 shows the SVC body. The SVC main body 10 is composed of a high impedance transformer 11 and a thyristor facility 12 (not shown) connected in antiparallel, which is connected in series to the system bus 3. The SVC body 10 is configured by a so-called thyristor control reactor (TCR) system.

On the other hand, CT that detects the load current in the circuit of variable load 4
5 is connected, and PT6 is connected to the system bus 3.
The voltage signal is taken out from the next side.

These load current signal and bus voltage signal are input to the reactive power detector (Q detector) 30 and the reactive power is calculated. The reactive power value obtained by this calculation is an instantaneous signal.

The output side of the Q detector 30 is input to the adder circuit 33 directly and via a Q average value detector (low-pass filter) 31.

Also the adding circuit 33 from the bias setting unit 32, it sets the bias Q _B corresponding to the half of the SVC body volume to be set (Q _SVC), and inputs.

On the other hand, a CT13 for detecting a current flowing through the SVC body 10 is coupled, the CT13 is connected to an average current detector (low-pass filter) 40 of the SVC body 10, the output side of which is input to an adding circuit 34, and the same. For the adder circuit, the rated current of the SVC body 10 is 1 P.U.
The reference voltage 41 corresponding to is input, and both inputs are compared here, and the difference signal is output. This difference signal is input to the integrator 55,
The output from the integrator 55 is input to the adder 33. The output side of the adder 33 is connected to the pulse generating circuit 34,
Thyristor from 34 firing thyristor by phase pulse
Twelve energization controls are performed. Reference numeral 7 is a synchronous power supply device for supplying a timing pulse which is a reference of a pulse generation phase in the pulse generation circuit 34.

The operation will be described below.

(1) When the reactive power of the fluctuating load is large, that is, when the flicker is large, the time constant of the integrator 55 is set to a large value, and therefore the difference ΔQ between the Q detector 30 and the Q average value detector 31 is ΔQ.
In addition, a current flows through the SVC body 10 based on a signal to which the bias Q _B applied by the bias setter 32, which is opposite to 1/2 of the capacity of the SVC body, is applied, and compensates for the fluctuation reactive power due to the fluctuation load.

(2) When the fluctuating load becomes light load or no load, the output signal from the Q detector 30 becomes zero, and therefore the bias current of 1/2 of the capacity of the SVC main body determined by the SVC current bias setting unit 32 results in a constant current. Become. However, the capacitor equipment 20
If the capacity is much larger than the capacity, the capacitor current exceeds the capacity and flows into the system in such a state, so that the system voltage rises.

(3) Next, when the SVC current becomes 1/2, the output voltage corresponding to the output current of the average current detector 40 of the SVC body is compared with the reference voltage 41, and the difference is integrated by the integrator 55, Outputs a slowly rising signal Q _S ,
Since the bias of SVC body capacity 1/2 by 32 is offset,
The SVC current becomes 100% current, suppressing the rise in system voltage.

Here, the output signal Q _in from the adder circuit 33 is Q _in = Q _B + Q _S = 0.

(4) Next, when the load changes, the existence of the integrator 55 becomes an obstacle, and a situation occurs in which proper Q control cannot be performed for a while.
The time constant of the integrator is about several seconds.

[Problems to be Solved by the Invention] As described in (4) following (3) above, the load is zero,
Alternatively, when the load is changed to be larger than the light load, the integrator 55 becomes an obstacle and the Q control cannot be properly performed, and the influence thereof is spread to the system. The present invention improves this point.

[Configuration of device] As described above, the average current of the SVC body conventionally installed is detected, the difference is obtained by comparing this with the rated current of the SVC body, the difference is integrated, and the addition circuit is integrated. Participating
Bias Q _B equivalent to 1/2 of SVC body capacity (Q _SVC ) is gradually canceled when variable load is zero or light load,
In contrast to 100% SVC current, the present invention does not use the control circuit as described above, but when the variable load becomes zero or light load, it immediately corresponds to 1/2 of the SVC body capacity. The bias Q _B is cut off from the thyristor control signal, and the current is 100% of the SVC body.

The present invention will be described below with reference to the embodiment shown in FIG. The same parts as those in FIG.

A power system 1 is connected to a system bus 3, a variable load 4 is connected to the bus 3, and a capacitor 21 and a series reactor 22 are connected.
It is assumed that the capacitor equipment 20 is connected.

On the other hand, the SVC body 10 by the TCR method is connected to the system bus 3.

On the other hand, CT that detects the load current in the circuit of variable load 4
5 is connected, and PT6 is connected to the system bus 3.
The voltage signal is taken out from the next side.

The load current signal and the bus voltage signal are input to the reactive power detector 30, and the reactive power is calculated. The reactive power value obtained by this calculation is an instantaneous signal.

The output side of the Q detector 30 is input to the adder circuit 33 directly and via a Q average value detector (low-pass filter) 31.

Also, a limiter circuit is provided on the output side of the Q average value detector 31.
60 is connected. The limiter circuit 60 has a limiter and a comparison function, and when the average reactive power value from the average value detector 31 of the load becomes a set value, for example, 1/10 or less of the SVC body capacity (Q _SVC ) or less, the relay Operate 53.

Reference numeral 32 denotes a bias setter, in which a bias Q _B corresponding to 1/2 of the capacity of the SVC main body is set, and is applied as a bias to the adder circuit 33 via a contact 54 operated by the relay 53.

The thyristor control signal from the adder circuit 33 is a pulse generator circuit.
The thyristor is energized by a thyristor firing phase pulse input from the pulse generator 34.
Reference numeral 7 is a synchronous power supply device for supplying a timing pulse which is a reference of a pulse generation phase in the pulse generation circuit 34.

[Operation] Generally, the sending voltage from the power supply side is kept within an allowable range, so the bus voltage at the installation point of the load and the SVC device decreases when the load is operating, and the load is When there is no load, the voltage is usually high.

According to the present invention, when the variable load Q is large (when the flicker is large), the flicker can be suppressed by the same Q detection control as in the conventional case.

When the fluctuating load becomes light or no load and the voltage rises, the average value of the load Q is naturally zero or small. This average value signal of Q is input to the limiter circuit 60, and if it is less than the set value, the relay 53 is operated and the signal of the bias Q _B is set to 0 by the contact 54 thereof. In this case, the bias Q _B may be switched to a bias smaller than Q _B.

Therefore, a zero or almost zero signal is input to the pulse generation circuit 34, and the SVC main body 10 is fully ignited (rated current), that is, 100% constant current. Therefore, the rise of system voltage can be suppressed.

When the fluctuating load becomes large and the reactive power fluctuation becomes large, the contact 54 is closed and the normal Q detection control is performed.

[Effect of the invention] as compared with the prior art shown in FIG. 2, the correction circuit of the bias Q _B by SVC body of the current detection and the current in the present invention is not required, the circuit configuration is simplified. According to the present invention,
A bias equivalent to 1/2 of the capacity of the main body of the reactive power compensator in the control device of the conventional reactive power compensator is turned on / off depending on the magnitude of the output signal from the reactive power average value detector, and a normal Q value is promptly obtained. Detection control and suppression of system voltage rise can be performed.

[Brief description of drawings]

FIG. 1 shows a block diagram of an embodiment of the present invention. FIG. 2 is a block diagram showing a conventional reactive power compensator. 30 ... Q detector, 31 ... Q average value detector, 32 ... bias setting device, 33 ... adding circuit, 34 ... pulse generating circuit,
53 …… Relay, 54 …… Relay contact, 60 …… Limiter circuit.

Claims (1)

[Scope of utility model registration request] 1. A reactive power compensator using a thyristor control reactor installed for the purpose of suppressing voltage flicker and voltage fluctuation, and a reactive power detector of a load and a reactive power average value detection connected to the detector. And a bias setting device that generates a bias equivalent to half the capacity of the reactive power compensator body, and a relay connected to the reactive power average value detector via a limiter circuit, and the reactive power of the load is Fluctuating reactive power is calculated from the output signal of the detector and the average value of the reactive power detector, and a bias corresponding to 1/2 of the capacity of the reactive power compensator main body from the bias setting device is added to this, and the reactive bias is removed. It is possible to obtain a signal for controlling the firing phase of a thyristor by turning it on and off by a relay that operates according to the magnitude of the output signal from the power average value detector. Control device for reactive power compensation device to symptoms.