Dynamic harmonic filter

Abstract

The invention provides a dynamic harmonic filter, mainly comprising a variable reactor (4), an anti-parallel thyristor trigger circuit (5), a control coil (6) and a capacitor group (7), wherein, one end of the variable reactor is in parallel connection with the capacitor group; two terminals of the anti-parallel thyristor trigger circuit are respectively connected with the both ends of the control coil to form a circuit; multiple groups of quick fuses (8) and a capacitor contactor (9) are in parallel connection with a series circuit of a capacitor (10) to form the capacitor group; when capacitive reactance of the capacitor group changes, the control coil is started under the action of the anti-parallel thyristor trigger circuit, and dynamically adjusts the inductance of the variable reactor. The dynamic harmonic filter of the invention forms a low-impedance loop to absorb the harmonic wave under harmonic frequency of f0; besides, the dynamic harmonic filter provides reactive current to improve power factor under the fundamental harmonic frequency. The dynamic harmonic filter creates conditions for reduction of harm of the harmonic wave to a transformer, a power cable, a motor, a control system, a communication system and the capacitor and the like.

Description

technical field [0001] The invention relates to technical fields such as overcoming harmonic hazards and improving power quality, and in particular to a dynamic harmonic filter used to dynamically adjust the inductance of a varactor to stabilize resonance frequency when the capacity of a capacitor changes. Background technique [0002] With the rapid development of industrial technology, many nonlinear loads, such as DC motors, DC power supplies, frequency converters, rectifier equipment, electroplating and electrolysis equipment, medium and high frequency induction heating equipment, battery chargers, thyristor temperature-controlled heating equipment, electric locomotives , communication equipment, audio-visual equipment, inverters, computers, etc. are connected to the power grid, and the harmonic content of the power grid is increasing year by year. Various hazards caused by grid harmonics are becoming more and more prominent, such as increasing the load of power faciliti...

AI Technical Summary

Problems solved by technology

In this way, there are some problems. For example, at the fundamental frequency, the traditional harmonic filter invests in a fixed capacitor bank to compensate the reactive power of the system, but due to the constant capacitive reactance, it is easy to cause overcompensation of the system; After being put into use for a period of time, the capacity of the capacitor will change. For example, the capacity of the capacitor will decay with temperature and time, resulting in a decrease in capacity. The capacitive reactance of the capacitor will increase, and the capacitance will decrease, so that the resonance frequency will increase. The filtering frequency of each unit of this type of filter is fixed, so the filtering effect will be greatly affected

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