A parallel active power filter

Abstract

A parallel connection type active power filter comprises a current collecting unit, a voltage collecting unit, an IGBT drive unit, an IGBT switch unit and a grid access unit. The parallel connection type active power filter is further characterized in that a DSP chip, an FPGA chip, a grid access current collecting unit and a system operation state collecting unit are further included, the output of the current collecting unit and the output of the voltage collecting unit are respectively connected with the A / D input end of the DSP chip, the DSP chip is used for instruction current signals opposite to detection harmonic signals of a power grid in direction, the FPGA chip modulates PWM output signals according to the instruction current signals and outputting the PWM output signals to the IGBT drive unit, the IGBT drive unit drives the IGBT switch unit to form harmonic currents (compensation currents), the harmonic currents are injected into the power grid through the grid access unit, the grid access current collecting unit collects compensation current signals output by the grid access unit and outputs the compensation current signals to the FPGA chip, and at least the FPGA chip uses the compensation current signals to modulate the PWM output signals. Compared with the prior art, the parallel connection type active power filter improves the flexibility, the reliability and the safety of application.

Description

Technical field [0001] The invention relates to a parallel active power filter, which belongs to the class of active power filter devices. Background technique [0002] With the development of technology, more and more non-linear loads are widely used in industry and people’s daily life. The existence of these non-linear loads in the power grid forms a large number of harmonics. On the one hand, they form reactive currents, which directly affect The power factor of the entire power system affects the operating efficiency of the power system. On the other hand, these harmonics are a kind of pollution and a public hazard to the power system. In addition to posing a threat to the safe and economic operation of the power system itself, The operating environment of power electronic equipment will also have extremely harmful effects, which may even endanger the normal operation of various advanced precision instruments and equipment in the fields of information technology equipment, mi...

AI Technical Summary

Problems solved by technology

The problem with the active power filter disclosed in ZL200910061816.4 is that some of its core signal analysis and control signal formation units are composed of discrete unit modules, and there are problems in the stability and reliability of the system during operation. , the switching harmonics formed during the operation of the electronic inverter system will be connected to the power grid in series, forming secondary pollution. In addition, the whole system is formed from harmonic sampling to form a control instruction current, and finally forms an output voltage through the electronic inverter system. The closed-loop control system of this kind of closed-loop control system is particularly easy to form self-excitation when there are switching harmonics at the output end. More importantly, the entire system of the active power filter disclosed in ZL200910061816.4 is not reliable. The operation monitoring and guarantee system, once there is an abnormal situation during operation, can only be intervened manually, so the operation risk is particularly high

For the problem of switching harmonics formed during the operation of the electronic inverter system, the inventor of this case noticed the solutions disclosed in Chinese invention patent ZL201010275272.4 and CN201310049218.1. The common point of these two solutions is to add a dedicated The second current transformer to detect the output current of the electronic inverter system is essentially the compensation current of the real-time acquisition device, which is compared with the collected load harmonic current to form a closed-loop feedback control. Application practice shows that, This method is not a good solution, because the load harmonic current essentially includes the harmonic current in the compensation current. In this case, it is very complicated in algorithm to compare the two, and the system resources It is very costly and directly affects the response speed. Obviously, timely response is one of the prerequisites for the application of active power filtering. In summary, it is obvious that the existing technology needs further improvement.

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