JPS58157344A - Self-excited converter - 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] (+1) Description of the Technical Field The present invention relates to an automatic conversion device that mutually converts alternating current power and direct current power. The present invention relates to a self-excited converter having a function of controlling the power so as not to become excessively high.

(b) Description of prior art As seen in the development of fuel cells and solar cells, and power storage using storage batteries, the use of converting direct current/power into alternating current power is increasing. As a device, a self-excited converter that can control reactive power as well as power conversion is being considered.

FIG. 1 shows an example of the configuration of an automatic converter.

Gate turn-or-sai risk (GT) with bridge configuration
A single-phase converter 1 consisting of a thyristor (SCa) or a thyristor (SCa) having a commutation circuit is connected to a DC power supply 2 and a transformer 4. The other winding of transformer 4 is connected to the three-phase power transmission system K as a Y connection.
II Continue. Note that 3 is the impedance corresponding to the leakage current of the transformer.

For the above-mentioned main circuit, it is common to use constant voltage control and constant power control to control the output voltage and output power of the converter to a reference value.

That is, the temporal change in the voltage magnitude obtained from the voltage detection circuit 7 is compared with a voltage reference 9 that can be set arbitrarily, and the control angle ψ shown in FIG. 2 is controlled so that the values become equal. This is the voltage control loop. The constant power control loop uses the detected values of the current detection circuit 6 and the voltage detection circuit 7 to compare the temporal change in the magnitude of power obtained by the power calculation circuit 8 with the power reference 10, and calculates the difference. This is a loop that controls the phase difference θ between the output voltage shown in FIG. 2 and the voltage generated by the converter so that the voltage becomes zero. Using these two loose control outputs, 13 pulses serve to give an ignition pulse to the converter so that the control angle ψ and phase angle O5 correspond to the required voltage and power reference values. This is a generation circuit.

If we close the switch 14 in Fig. 1 and connect the two wires through the resistor 15, assuming a short-circuit accident in the AC system, the voltage between the short-circuited lines will decrease, so as shown in Fig. 3,
V and a change greatly to Vta, v and b to &g. In this way, when the voltage changes, even if constant power control and constant voltage control are performed, V, a and V, a and vlb decrease, etc., and the voltage generated by each phase of the converter and the AC side winding of the transformer change. Each phase voltage, that is, the converter current of the a and b phases that are connected to each phase of the converter increases.The magnitude of the first current is also related to the value of the resistor 15, but if this current increases, the converter will fail. Therefore, it is necessary to take measures to reduce the current and protect the converter.

(e) Purpose of the Invention The present invention has been made in view of the above-mentioned circumstances, and is intended to provide a self-commutated converter connected to a three-phase AC system, in which conversion at the time of a system fault occurs, and each phase at the connection point of the converter. Provide a circuit that detects temporal changes in voltage magnitude and its phase, a circuit that controls the voltage generated by each phase of the converter so that it is equal to that voltage, and a circuit that switches pulses between normal operation and fault conditions. In particular, it is an object of the present invention to provide a self-commutated converter having a line maintenance function against overcurrent during a system fault.

(d) Structure of the Invention The present invention will be explained below based on an embodiment shown in the drawings.

In FIG. 4, each phase voltage detection circuit 7 is connected to an AC winding terminal of the transformer 4, and its output is given to a firing time calculation circuit 19 for each phase pulse. Ignition time calculation circuit for each phase pulse 1
The output of 9 is given to the gate circuit of the converter 1 of each phase through the pulse generation circuit 13 and the failure determination pulse control circuit 16.

Note that the failure determination pulse control circuit 16 is also connected to the output of each phase voltage comparison circuit 17 which receives the seven phase voltage detection circuits as inputs.

(e) Function of the Invention Next, the function of the present embodiment configured as described above will be explained. Assuming a short circuit accident by closing the switch 14, the voltage between the lines that caused the short circuit decreases, and each The value and phase of the phase voltage changes. Each phase voltage detection circuit 7 detects the value and phase of each phase voltage.

Based on the detected values, the firing time calculation circuit 19 for each phase pulse generates the waveform as shown in FIG.

Rectangular wave (1) Calculate the time to generate pulses of each phase so that the amplitude of the fundamental wave component v1a(f) of 1m is equal to the amplitude I of the detected nine voltages, and the phase angle θ· is zero.

The pulse generating circuit 13 is responsible for generating pulses to the converter based on the calculated values. In other words, it is possible to control the pulses applied to the converter so that the fundamental wave components of the voltages v, a, Vl b , V, c generated by the converter are equal to the detected phase voltages. In the event of a failure, the current flowing through the impedance 3 of each phase, that is, the converter current, can be reduced.

By the way, as explained in Figure 1, in steady state it is necessary to give pulses based on constant voltage control and constant power control to the converter, so it is also possible to switch the pulses between steady state and system fault state. The failure determination pulse control circuit 16 is necessary and performs this function. In other words, the solder pressure detection times for each phase! By comparing the values of each phase voltage in the comparison circuit 17 for each phase voltage based on the value of 87', fault condition dust is determined from the difference in each phase voltage, and the fault discrimination pulse control circuit 1
Send a pulse switching signal to 6.

(f) Pond Embodiment Although the explanation has been given for a 6-phase converter in FIG. 4, the present invention can also be applied to a 12-phase converter 2 shown in FIG.

In Figure 5 of the 12-phase converter, a 3-winding transformer of 4 is used, and the AC side voltage is 3 for the converter side winding voltage of the transformer.
Since they are connected to shift the phase by 0, it is necessary to correct them in order to calculate the pulse firing time required by each converter from the voltage detected by each phase voltage detection circuit 7. . The voltage conversion circuit 18 performs the correction.
Six auxiliary transformers are connected in the same way as the transformers and connections in Figure 5, and the six output voltages obtained by inputting the n values obtained from each phase voltage detection circuit 7 are used as a pulse firing time calculation circuit. 14. That is, by adding the positive conversion circuit 18, even if the present invention is applied not only to 12-phase converters but also to other multi-phase converters, the functions thereof will not be impaired.

(g) Effects of the Invention As described above, according to the present invention, by detecting the output voltage of the converter, the pulse generation time such that the voltage generated by the converter becomes equal to the detected value is determined. By switching the on-off pulse applied to the converter gate between when a system failure occurs and when the converter is in a steady state, it is possible to suppress the overcurrent that flows through the converter at the time of a system failure, resulting in an inexpensive and highly reliable converter. can be provided.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a self-commutated converter connected to the power grid, Figure 2 is a diagram explaining the phase angle θ and control angle ψ, Figure 3 is a diagram showing voltage changes in the event of a system failure, and Figure 4 is a diagram showing the change in voltage during a system failure. This figure is a circuit diagram showing one embodiment of the present invention, and FIG. 5 is a circuit diagram showing another embodiment of the present invention. 1... Thyristor with a bridge configuration commutation circuit (
sca)t! or gate turn-off thyristor (UTO)
) converter 2...DC power supply 3...impedance 4 corresponding to the leakage impedance of the transformer...transformer transformer 4...phase-shifted pressure converter transformer 5...AC system, 6. Current detection circuit, 7.7
...Each phase voltage detection circuit, 8...Power calculation circuit, 9...
・Voltage reference generation circuit, 10・Power reference generation circuit, 11.
...Voltage control system amplifier 12...Power control system amplifier. 13.13...Pulse generation circuit, 14...Failure occurrence switch, 15...Resistance at failure point, 16...Failure determination pulse control circuit, 17...Each phase voltage comparison circuit, 18... Voltage conversion circuit, 19...Pulse firing time calculation circuit. (7317) Agent Patent Attorney Aide Ken fn(4
or 1 person) Figure 1 371 Figure 2 Figure 3 2b Figure 4/7

Claims (1)

[Claims] In a self-excited converter that has a plurality of self-excited unit converters and combines the outputs of these self-excited unit converters to obtain a multiphase AC output, a voltage detection circuit that detects the voltage of each phase, and this voltage A circuit that calculates the ignition pulse to be applied to the self-excited unit converter according to the amplitude and phase of the output voltage of each phase detected by the detection circuit, and a dust accident due to the magnitude of the detected output voltage. An automatic conversion device that is equipped with a circuit that determines the state and controls the pulse (between a steady state and an accident).