A low-voltage transformer area electric energy quality control device

Abstract

The invention provides a low-voltage transformer area electric energy quality control device comprising a transformer and a control loop. The transformer is a ZigZag transformer. The control loop comprises an inverter, a sampling circuit, a PWM modulator, a protection circuit and a filter. With the transformer and the control loop, zero-sequence current of external lines can be effectively detected and can be timely compensated for effectively to filter zero-sequence current.

Description

technical field [0001] The invention relates to a device for controlling electric energy, more specifically, relates to a device for controlling the quality of electric energy in a low-voltage station area. Background technique [0002] Over the past ten years, with the rapid development of power electronics technology, the number of high-power power electronic devices in the regional power distribution system has increased day by day, which has not only improved the efficiency and automation level of the regional industrial devices, but also brought about its power distribution system. Reactive problem. Due to the existence of inductive loads, there is a phase difference between the current and voltage in the regional distribution network, thereby generating reactive power and resulting in a low power factor. In addition, another type of problem is caused in the distribution network, that is, the three-phase unbalanced problem. The reason is that the traditional three-pha...

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Problems solved by technology

Due to the existence of inductive loads, there is a phase difference between the current and voltage in the regional distribution network, thereby generating reactive power, resulting in a low power factor

In addition, it also causes another type of problem in the distribution network, that is, the three-phase unbalance problem

The reason is that the traditional three-phase four-wire distribution transformers are mostly connected in the regional distribution network, and the transformer capacity is less than 100kVA, accounting for about 50% of the global transformers, and these small-capacity transformers are vulnerable to seasonal single-phase loads. (such as single-phase tea frying machines, etc.), which in turn causes low-voltage single-phase loads in the distribution network to be unable to be fully distributed manually, the actual operating rate of the distributed loads differs too much, and the uncontrollable capacity increase of single-phase users is inevitable. Three-phase unbalance problem caused by low-voltage distribution network

[0003] This unbalanced three-phase load will inevitably lead to an increase in the neutral wire current. Since it is equal in magnitude and opposite in direction, superposition on the neutral wire will cause neutral wire overload, overheating, and electromagnetic interference, affecting the supply voltage waveform, insulation Layer damage, lower power factor, lower service life of transformers and electrical equipment, etc., will ultimately seriously affect the regional voltage qualification rate index

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