JPS63146113A - Reactive power controller - Google Patents

Abstract

PURPOSE:To enlarge a protective range, and to prevent a damage of main circuit parts, which is caused by a leading overcurrent, by allowing both leading and lagging overcurrents to have drooping function. CONSTITUTION:The titled control unit is provided with a means for outputting two dropping characteristic signals in each opposite direction, when an output overcurrent of an inverter 4 is detected and goes to an overcurrent exceeding a set value, and a means for detecting a phase difference to an output voltage of an output current of the inverter 4, selecting two signals in accordance with lead and lag, and inputting them to an automatic voltage control circuit 10. In such a state, an overcurrent is limited by allowing an inverter output voltage to rise against an overcurrent of a leading current, and fall the inverter output voltage against an overcurrent of a lagging current. In such a way, a protective range can be enlarged.

Description

[Detailed Description of the Invention] A. Industrial Field of Application The present invention relates to a reactive power control device when an inverter and another power source such as a power system are operated in conjunction with each other, and the present invention relates to a reactive power control device when an inverter and another power source such as a power system are operated in conjunction with each other. It relates to something with voltage droop characteristics.

B1 Summary of the Invention An inverter is operated in conjunction with another power source, the phase of the output voltage and output current of the inverter is detected, and when this phase difference exceeds a set value, the voltage of the inverter is controlled by an automatic voltage control circuit. When the output overcurrent of the inverter is detected and the overcurrent exceeds the set value, C: Two drooping characteristics in opposite directions. The present invention is equipped with means for outputting a signal, and means for detecting the phase difference between the output current of the inverter and the output voltage, and selecting the two signals according to lead and lag, and manually inputting the signals to the automatic voltage control circuit. It is characterized in that the inverter output voltage is increased in response to the overcurrent of the delayed current, and the inverter output voltage is decreased in response to the overcurrent of the delayed current to perform overcurrent limitation.

C6 Conventional technology In electric power systems, etc., as power transmission systems become longer distances and have larger capacities, resulting in greater reactance, maintaining stability becomes an important issue. Reactive power compensation is performed by the /parter ζ2.This control method generally gives the voltage control loop a voltage drooping characteristic due to the reactive power 1:.

That is, FIG. 3 shows a conventional reactive power control circuit that operates in conjunction with this type of inverter and another power source, where 1 is another power source that is operated in conjunction with the inverter, which will be described later, 2 is a load connected to the other power source 1, L is a reactance, 3 is a rectifier that rectifies the power of the AC power source AC, and 4 is an inverter, the DC input side is connected to the rectifier 3, and the AC output side is connected to the other power source 1 via the breaker CB. There is. 5 is a reactive power detection circuit;
The output voltage and output current of the inverter 4 are extracted from two voltage detectors and a current detector CT, and are used as input to detect the phase difference between the voltage and current. B is a non-camellia reactive power control amplifier which compares a signal proportional to the phase difference detected by the reactive power detection circuit 5 with the reactive power setting device S1 and amplifies the difference signal. 7 is an AC-DC converter circuit that replaces the output voltage of the voltage detector PT with a DC signal; 8 is an overcurrent droop characteristic circuit that inputs the output of the current detector CT; When the flow exceeds the one set in S2, the output signal is suddenly decreased. 9 is a comparator that compares the setting of the output voltage setting device SS; direct and length-direct R conversion circuit 7;
The output of the reactive power control amplifier 8 is also input to the gate circuit 11 of the inverter, and the gate circuit 11 is controlled to control the output voltage of the inverter.

To control reactive power, when the output voltage of inverter 4 is made larger than the grid voltage, inverter 41111 supplies lagging reactive power to the grid side (taking leading phase reactive power from the grid side).
In addition, if the output voltage of the inverter 4 is made smaller than the grid voltage, conversely, the inverter side supplies the grid side ζ: phase-advanced reactive power, and the power factor on the grid side is adjusted. That is, when the reactive power exceeds the set value of the reactive power setting device S1, the automatic voltage control circuit 1
The gate circuit 11 is controlled in the direction of lowering the output voltage of the inverter 4 to supply phase-advanced reactive power.

In addition, when the output current of the inverter 4 increases by controlling the reactive power and the overcurrent exceeds the set value of the overcurrent setting device S2, the output signal of the overcurrent droop characteristic circuit 8 is outputted via the comparator e. The output of the automatic voltage control circuit 10 controls the gate circuit 11 to lower the output voltage of the inverter 4 and limit overcurrent.

D0 Problems to be Solved by the Invention According to the above control device, the current phase of the system is voltage phase 4.
It has an adjustment function when supplying binary phase reactive power in the delayed direction relative to system 2, that is, system 4, but does not have a function when supplying delayed reactive power to the opposing ship system. Therefore, depending on the load, an overcurrent droop characteristic function is required even for leading current, but there is a problem that this cannot be dealt with.

Means for solving problem E1: means for detecting inverter output overcurrent and outputting two droop characteristic signals in opposite directions when the overcurrent exceeds a set value; and output voltage of inverter output current. means for detecting the phase difference between the two signals and selectively inputting the two signals to the automatic voltage control circuit by leading and delaying them.

28 Action When the lead current flows in excess of the set overcurrent value, the output of the function generator is increased, the output voltage of the inverter is increased, and the lead current is decreased, and conversely, the lagging current flows in excess of the set overcurrent value. When this occurs, the output of the function generator is reduced to lower the output voltage of the inverter and reduce the delay current.

G. Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention. Components that are the same as or similar to those in FIG. 3 are given the same reference numerals and their explanation will be omitted. Reference numeral 20 denotes a function generator for overcurrent drooping characteristics, which takes the output of the current detector CT and the output signal of the reactive power detection circuit 5 as input signals, and sends the output signal to the automatic voltage control circuit 10 via the comparator 8. Add.

Figure #f2 is a circuit diagram showing an embodiment of the overcurrent droop characteristic function generator 20 in Figure 1, in which the current of the current detector CT is compared with the overcurrent setter SR, and the overcurrent exceeding the set value is detected. an overcurrent detection amplifier 21 that outputs a drooping output signal A and an output signal B obtained by inverting the drooping output signal A, and a reactive power detection circuit 5.
A phase detection comparator that operates based on the lead or lag of the current phase detected by the comparator 22+.
:! The output signal A of the overcurrent detection amplifier 21 and the output signal δ
It is composed of analog switches 23, 24 and an inverting circuit 25 that selectively output the signal B and the comparator 9 (= output).

There is.

Next, the effect will be explained. The phase of the output voltage and output current of the inverter 4 is detected by the reactive power detection circuit 5, and the detected signal is compared with the reactive power setter S1, and when it exceeds the set value, it is amplified by the reactive power control amplifier 6. Automatic voltage control times M
10 is done by two people as in the past, but the present invention is characterized in that the above-mentioned function generator 20 is newly provided in place of the overcurrent droop characteristic circuit. Therefore, the output current of the inverter 4 is If it lags behind the voltage, the output signal of the reactive power detection circuit 5 is the signal (G), so when this is manually input to the function generator 20, the phase detection comparator 22 in FIG. 23 is closed and the output signal A of the overcurrent detection amplifier 21 is input to the automatic voltage control circuit 10 via the comparator S. In this state, the output of the current detector CT is set to the overcurrent setting device S20. When the value exceeds the value, the output signal is suddenly reduced to lower the output voltage of the inverter 4 and reduce the lagging current.Reverse 1: If the output voltage of the inverter 4 advances with respect to the output voltage, The output signal of the reactive power detection circuit 5 is different from the signal (c), and the inversion circuit 25 is inverted by the output of the phase detection comparator 22 of M2, and the analog switch 24 is closed and the overcurrent detection amplifier 21 is inverted. The output signal B II is connected to the automatic voltage control circuit 10. In this state, when the output of the current detector CT exceeds the set value of the overcurrent setter 5t (l), the output signal is suddenly increased and the inverter The output voltage of 4 is increased and the lead current is decreased.

H0 effect As mentioned above, since it has a painter's function for both leading and lagging overcurrent C, the protection range is expanded, and in particular, damage to main circuit components caused by leading overcurrent is completely prevented. In addition, since the objective can be achieved by adding a simple control circuit, it is inexpensive and has the effect of being C: Possible.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing an implementation of an overcurrent droop characteristic function generator used in the present invention, and Fig. 3 is a conventional reactive power control circuit. It is. 1...Other power supply, 2...Load, 4...Inverter,
5... Reactive power detection circuit, 6... Reactive power control amplifier, 10... Automatic voltage control circuit, 11... Gate circuit, 20... Function generator for overcurrent droop characteristic, 21...
- Overcurrent detection amplifier, 22... Phase detection comparator, 52G... Overcurrent setting device.

Claims (1)

[Claims] The inverter is operated in conjunction with another power source, the phase of the inverter's output voltage and output current is detected, and when this phase difference exceeds a set value, the automatic voltage control circuit controls the output voltage of the inverter to detect the phase difference. is controlled within a set value, when the output current of the inverter is detected and this detected current exceeds the overcurrent set value, an output signal A that suddenly decreases, and an output signal that increases conversely. B
means for generating two signals; and means for detecting whether the output current of the inverter leads or lags the output voltage, and outputs the output signal B when the output current is a lead, and outputs the output signal A when the output current is a lag.
A reactive power control device comprising: means for inputting each of the voltages into the automatic voltage control circuit.