CN85203734U - Wattless power compensating device - Google Patents

Abstract

The utility model discloses a wattless power compensating device, which can be used for wattless power compensation for a power supply. Compared with the traditional wattless power compensation method, the utility model is characterized in that the utility model conduct compensation according to the actual measured value of the power factor, the utility model utilizes a phase locked loop which is designed according to a principal of minimum ripple to achieve the compensation under the control of a microcomputer, so the utility model is a digital compensation apparatus. The utility model has the advantages of short time of regulation, stable running, high sensitivity, small volume, low cost, etc.

Description

A kind of inactivity compensation device

A kind of reactive power compensation device can carry out the compensation of power supply reactive power according to the measured value of power factor.

Traditional Compensation methods of reactive power, it is the reactive power that is detected load by analog quantity, decides the capacitance that drops into or excise building-out capacitor according to giving fixed threshold value again.But in service in reality, under same reactive power value, the active power of load is different, thereby only compensate according to reactive power, tend to cause overcompensation, promptly bring in from power supply, capacitive load can appear, thereby increased the number of times of round switching building-out capacitor, this is undesirable, the invention is characterized in, it is to decide according to detected power factor value to drop into or the capacitance of excision building-out capacitor, it has reflected the relation between active power and the reactive power all sidedly, thereby has just fundamentally overcome above-mentioned defective.And, the detection of power factor is under the control of microcomputer, realize by a phase-locked loop that designs by least ripple principle, compare with traditional analog compensation arrangement, it is a kind of digital reactive power compensation device, can in each cycle, detect, thereby just improve the sensitivity and the governing speed of compensation arrangement greatly power factor.

The principle of this reactive power compensation device is as follows: the voltage and current signal of detection power factor value is earlier respectively by becoming square-wave signal behind the waveform transformation circuit according to this.Voltage square wave signal wherein will be sent to the phase-locked loop by the least ripple principle design, and it is made up of phase discriminator, low pass filter, voltage controlled oscillator and frequency divider.The Frequency Design of voltage controlled oscillator becomes 360 times of frequency input signal, thereby, the interval of the adjacent pulse of voltage controlled oscillator output is 1 ° just, voltage square wave signal by the phase-locked loop input is converted to pulse train OP, simultaneously, the square-wave signal of voltage and current then forms the square-wave signal v ' that can represent phase difference between them after by phase difference detecting circuit

I '.Like this, OP, v '

I ' and voltage square wave signal v ' can obtain being used for representing the count pulse CP of the phase difference between voltage and current after being sent to the phase difference impulse circuit, and are sent to computer.If with voltage square wave signal as the step-by-step counting control signal, with current square-wave signal as the lead-lag control signal, then under these two signal effects, computer just can calculate power factor according to the value of CP, and detects capacitive load or inductive load.Just can determine the capacitance of the building-out capacitor that drops into or excise then by o controller.Correspondingly, the voltage signal V of input is converted to excess voltage detection signal V behind overvoltage signal input circuit and voltage comparator _PAnd be sent to computer.Like this, the overvoltage that computer just can be carried out line voltage detects, and excises whole building-out capacitors by o controller after overvoltage occurring, treats to begin to carry out the compensation control of reactive power after voltage recovers normally again.O controller wherein by the display that can show realtime power factor, show that relay and contactor that each road building-out capacitor drops into the light-emitting diode of situation, shows superpotential light-emitting diode and is switched on or switched off each road electric capacity form.

Thereby, comparing with traditional reactive power compensator, that the present invention has is stable, the adjusting time is short, highly sensitive, volume is little and plurality of advantages such as with low cost.

Description of drawings:

Fig. 1: reactive power compensation device

1---the voltage signal input circuit;

2---filter;

3---the waveform transformation circuit;

4---phase-locked loop;

5---phase difference detecting circuit;

6---the phase difference impulse circuit;

7---voltage comparator;

8---computer;

9---o controller;

10---phase discriminator;

11---low pass filter;

12---voltage controlled oscillator;

13---frequency divider;

14---current transformer;

V---voltage waveform;

V '---voltage square wave (step-by-step counting control signal);

I '---electric current square wave (lead-lag detection signal);

V '

I '---phase signal;

OP---the pulse train of voltage controlled oscillator output;

CP---count pulse;

V _P---excess voltage detection signal.

Fig. 2: oscillogram

Claims (2)

1, a kind of reactive power compensation device is characterized in that, it is a kind of digital compensation arrangement of microcomputerization.

2, according to claim 1, wherein said digital compensation arrangement is characterized in that, its design has a phase-locked loop by the least ripple principle design.

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