Regulating system for controlling three-phase imbalance in electrical transformer district

Abstract

The invention discloses a regulating system for controlling the three-phase imbalance in an electrical transformer district. The regulating system for controlling the three-phase imbalance in the electrical transformer district comprises a data acquisition module, a master controller, a single-phase load phase changing extension set and a three-phase load phase changing extension set; the master controller is connected with each of the single-phase load phase changing extension set and the three-phase load phase changing extension set and is used for controlling the single-phase load phase changing extension set to shift the phase of single phase-loaded single phase current and controlling the three-phase load phase changing extension set to regulate and switch three phase-loaded three-phase current among a phase A, a phase B and a phase C according to the imbalance degree of the three-phase current of a bus on a low voltage side and the imbalance degree of the three-phase current of the bus of each branch acquired by the data acquisition module. The single-phase load phase changing extension set and the three-phase load phase changing extension set are arranged for regulating cooperatively, so that the three-phase imbalance degree of the current of the phase A, the phase B and the phase C of the bus of on the low-voltage side and the three-phase imbalance degree of the currentof the phase A, the phase B and the phase C of the bus of each branch are reduced.

Description

technical field [0001] The invention relates to the technical field of low-voltage load distribution of power distribution transformers, in particular to an adjustment system for controlling three-phase unbalance in a distribution transformer area. Background technique [0002] The end users of the low-voltage distribution power system include a large number of single-phase loads and three-phase loads, especially commercial and residential facilities, such as air conditioners, computers, electric water heaters, refrigerators, lighting and various household appliances, etc., and the number is increasing , the power is getting bigger and bigger, and the seasonality and randomness of electricity consumption will cause the dynamic imbalance of the three-phase load to become more and more serious. [0003] When the three-phase load is balanced, the three-phase currents are equal. Because the fundamental wave phase angle difference is 120 degrees, the vector sum of their neutral l...

AI Technical Summary

Problems solved by technology

The neutral line current is shunted in the windings of each phase of the distribution transformer with current components of equal magnitude and same direction at the neutral point, which is called zero-sequence current. When the three-phase load is seriously unbalanced, the distribution transformer will generate relatively large Large zero-sequence current, the zero-sequence current flowing in the distribution transformer will inevitably generate zero-sequence magnetic flux, the zero-sequence magnetic flux passes through the iron core, metal shell and heat pipe of the transformer to form a circuit, and the zero-sequence magnetic flux cuts the metal components of the transformer Induction potential is generated, and a current is formed in the metal conductor, that is, eddy current. The eddy current flowing in the metal conductor of the transformer will generate heat, that is, eddy current loss, which will increase the loss of the transformer, reduce the power factor, and even endanger the safe operation of the transformer in severe cases.

[0004] The dynamic unbalance of the three-phase load brings serious harm to the power system. The dynamic unbalance of the three-phase load will cause increased line loss, additional iron loss of the transformer, voltage offset, and additional power system. Copper loss, the increase of additional copper loss will cause the transformer to heat up and reduce the operating efficiency of the transformer

[0005] In the prior art, the problem of unbalanced three-phase loads only involves the adjustment of three-phase balance of single-phase loads. With the increase of three-phase loads, only adjusting from single-phase loads will result in low accuracy of adjustment results

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