JPH07101973B2 - Voltage fluctuation suppression device - Google Patents

Description

Description: TECHNICAL FIELD The present invention is capable of suppressing bus voltage fluctuation even when the bus voltage of the power system is unbalanced and sharply fluctuated, and suppresses voltage fluctuation composed of a thyristor control reactor and a parallel capacitor. Regarding the device.

[Object of the Invention]

FIG. 1 shows an example of the voltage fluctuation suppressing device. 4 in the figure
Is a series reactor, 5 is a thyristor switch, the series reactor 4 and the thyristor switch 5 are connected in series, and the capacitor 6 is connected in parallel thereto.

1 indicates an infinite bus, 2 indicates a power source impedance, and 3 indicates an installation bus. A PT7 and a thyristor control device 8 which receives an output signal of the PT7 are connected to the installation bus bar 3. 81 is a voltage detector, the output of which is a subtractor
At 82, the reference voltage Vref is compared, and the signal ΔVu-v is input to the regulator 83, an ignition control pulse is generated from the pulse generator 84, the thyristor switch 5 is controlled, and the energization control of the series reactor 4 is performed. It adjusts the reactive power consumption and suppresses voltage fluctuations.

The series reactor circuit controlled by the thyristor switch has a three-phase structure as shown in FIG. 2 in detail, and the voltage detector 81 shown in FIG. Is detected, the reactor of each phase is controlled, and the line voltage of each phase is controlled to be constant.

However, the voltage change due to the unbalanced load also affects other unrelated phases, and there are the following problems when only the change in each line voltage is detected.

Figure 3 A shows a circuit diagram of a case where a single-phase reactor X _L is loaded in the infinite bus voltage system. However, the resistance component of the power supply impedance of the system is ignored. The relationship between the phase voltages at this time is shown in FIG. The voltage detector 81 detects the line voltage, which changes from Vsu-v to Vu-v between u and v, and also changes between vw and wu.

However, considering the case where such a single-phase reactor load suddenly occurs and the fluctuation due to it is suppressed as quickly as possible, the voltage drops between uv, vw, and wu. Therefore, each phase control circuit functions to squeeze the reactor current and increase the voltage. U-
Although it is sufficient to operate only the reactor between v, all the phases operate and the fluctuations are suppressed while interfering with each other, so it takes time to reach the target value.

Of course, the conventional circuit configuration will eventually settle in a state in which fluctuations are suppressed, but it is difficult to quickly respond to sudden fluctuations.

[Disclosure of Invention]

The present invention detects the voltage imbalance due to the unbalanced load and changes the reactive power consumed so that the voltage fluctuation can be suppressed in a quick response when the load suddenly changes unbalanced and sharply changes. In a circuit that suppresses imbalance, the sum of the two phase voltage fluctuations that form one line voltage fluctuation and the difference between the remaining one phase voltage fluctuations is taken as the control signal between the corresponding lines. The voltage fluctuation suppressing device includes an unbalanced voltage detecting device that can be independently converted into information that can suppress voltage fluctuations without being interfered with each other and can be used for controlling each line reactive power.

Hereinafter, the thyristor control device used in the present invention will be described with reference to FIG.

First, from the bus bar 3, each phase voltage is measured by PT and converted into direct current by each voltage detector 81 to obtain Vu, Vv, Vw.

Next, the set value Vref is compared with the subtractor 82 to obtain each phase voltage fluctuation ΔVu, ΔVv, ΔVw, which is input to each adder / subtractor 85 as shown in the following equation (1) to perform an operation.

These ΔV _U −v, ΔV _V −w, and ΔV _W −u are input from the respective regulators 83 of FIG. 1 as control signals of the reactive power between the lines of the phases obtained by summing the voltage fluctuations. The thyristor switch 5 is controlled, the energization current of each reactor 4 is individually controlled, and reactive power consumption is controlled.

Since the above formula (1) corresponds to the fluctuation detection value obtained by removing the interference component between the respective phases when the three phases are unbalanced, the detection values do not cause mutual interference of the respective phases and set the target values independently of each other as will be described later. The target value can be reached extremely quickly.

[Operation, effect]

Considering the example in FIG. 3, △ Vw = 0 However, | Vs | = | Vsu | = | Vsv | = | Vsw | That is, the voltage fluctuation is detected only between uv and v-w.
Voltage fluctuations are not detected during the interval between w and u. By this signal, the reactor is controlled so as to increase the voltage only between u and v, and the reactor between vw and wu does not require a control operation, so that the single phase load It is possible to perform proper and high-speed control without receiving interference from other phases. In the above, the example of the reactor in which the fluctuating load is a single phase has been described, but it goes without saying that the same measure can be applied to any unbalanced load.

If the current of the load causing the voltage fluctuation can be measured, the reactive power of the load is detected and its output signal is
If the reactor is controlled by adding it to the output of the regulator 83 in the figure, the residual voltage fluctuation in the reactive power detection control moves in such a direction as to be corrected by the control system of the present invention.

As described above, it is possible to quickly suppress sudden voltage fluctuations.

[Brief description of drawings]

FIG. 1 shows an example of a voltage suppression device to which the present invention is applied. FIG. 2 is a detailed diagram of a reactive current circuit including a series reactor and a thyristor switch. FIG. 3A is an explanatory diagram of a circuit when a single-phase load is connected, and FIG. 3B is an explanatory diagram of each phase and a voltage relationship between the phases when the load connection is made. FIG. 4 shows an example of the thyristor control device used in the present invention. 1 ... Infinity bus, 2 ... Power source impedance, 3 ...
Bus bar, 4 ... Series reactor, 5 ... Thyristor switch, 6 ... Parallel capacitor, 7 ... PT, 8 ... Control device, 81 ... Voltage detector, 82 ... Subtractor, 83 ... Regulator,
84 …… Pulse generator, 85 …… Adder / subtractor.

Claims (1)

[Claims] 1. An unbalanced voltage due to an unbalanced load is detected,
In the circuit for controlling the imbalance by changing the consumed reactive power, the sum of the two phase voltage fluctuations forming one line voltage fluctuation is taken as the difference between the remaining one phase voltage fluctuations. A voltage fluctuation suppressing device which is used as a control signal for reactive power between lines of the summed phases.