An energy-saving filter type power transformer

Abstract

The invention discloses an energy-saving filtering power transformer, which comprises a transformer main body and a main circuit. The transformer main body includes a primary terminal and a secondary terminal. The primary terminal is connected to the mains, and the secondary terminal is connected to the main circuit. 1. The main capacitor, the main inductance coil, and the main capacitor form a series resonance or parallel resonance on the main circuit. The inductance of the main inductance coil can be controlled and adjusted according to the magnitude of the higher harmonic component on the secondary end. The power transformer also includes a signal circuit, the signal circuit is connected in parallel on the side of the main circuit close to the secondary terminal; the signal circuit includes a signal resistor and several signal branches, and each signal branch is provided with a first inductance, a first capacitor and a At the signal transmission end, the inductance and capacitance on each branch form the high-order resonance at this position. The signal transmission end on each branch obtains the branch current and uses it to control the inductance of the main inductor coil.

Description

technical field [0001] The invention relates to the field of circuit filter transformers, in particular to an energy-saving filter power transformer. Background technique [0002] Due to the complexity of the equipment of each user in the power grid, such as many induction motors, frequency regulators and many devices that do not operate with power frequency current, they transmit the load current of the power grid with many high-order harmonic currents. For example, there are not only 50hz power frequency currents in the power grid, but also several harmonic currents with multiple frequencies of 3, 5, 7..., if this part of current (voltage) reaches the ordinary user end, it is likely to damage the user's equipment , so effective harmonic suppression means are needed. [0003] In the prior art, harmonic suppression is divided into passive filters and active filters. Among passive filters, double-tuned filters are widely used. Combining series resonance and parallel resonanc...

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Problems solved by technology

[0003] In the prior art, harmonic suppression is divided into passive filters and active filters. Among passive filters, double-tuned filters are widely used. Combining series resonance and parallel resonance, they can effectively filter two specific frequency (the most commonly used is the frequency corresponding to the 3rd and 5th order), but when the harmonic in the power grid is the third frequency, there is nothing you can do, although the common ones are the 3rd and 5th order harmonics, but , as long as there is a seventh-order harmonic with a large effective value, then the device at the user end will be greatly damaged. Moreover, no matter whether the harmonic current of the 3rd or 5th order in the circuit is large, its impedance always exists in the circuit Among them, it will occupy power to form reactive power loss and reduce the overall power factor. Sometimes we hope that when the effective value of harmonic current of this order is very small, we will not filter this order, but there will be a larger harmonic current in the power grid. filter the order current

The filter of the existing device can only be achieved by the active filter. However, when the active filter is working, due to the filtering principle, it will consume a lot of power. The passive filter filtering principle is built in the circuit structure for a certain frequency In a low-resistance path, other frequency currents pass through the load, while most of the current at a specific frequency passes through the resonant path, which is equivalent to short-circuiting the load at a specific frequency, so in principle it can be completed without consuming energy, while active In short, the working principle of the filter is to superimpose the current of the corresponding order in the circuit to achieve the purpose of elimination. The superimposed high-order current needs to be provided by an independent power supply

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