Three-phase voltage unbalance degree determination method and device for wind power collection area

Abstract

The invention provides a three-phase voltage unbalance degree determination method and device for a wind power collection area. The method comprises the steps of determining a three-phase impedance matrix of an unbalanced line according to line parameters of the wind power collection area; establishing an equivalent model according to power grid parameters and a topological structure of the wind power collection area, and determining three-phase voltage and three-phase current of an equivalent node in the equivalent model; determining a positive sequence voltage and a negative sequence voltageof an equivalent node of the wind power collection area according to the three-phase impedance matrix, the three-phase voltage of the equivalent node and the three-phase current; and determining thethree-phase voltage unbalance degree of the wind power collection region according to the determined positive sequence voltage and negative sequence voltage of the equivalent node of the wind power collection region. By utilizing the method, the key factors influencing the three-phase voltage imbalance of the wind power plant can be simply and clearly analyzed, and the method has important guidingsignificance for exploring the voltage imbalance mechanism of a large-scale wind power collection region.

Description

technical field [0001] The invention relates to electric power technology, in particular to a method and device for determining the unbalanced degree of three-phase voltage in a wind power collection area. Background technique [0002] Wind power mostly adopts the mode of large-scale centralized development and long-distance transmission. Due to the lack of support from conventional power sources and the weak grid structure, voltage imbalance often occurs in areas where large-scale wind power gathers. Severe voltage imbalance will endanger the safe and stable operation of wind farms and power grids. Unbalanced voltage will cause heating and loss of wind turbine stator and rotor windings, and even trigger the unbalance protection action of wind turbines, resulting in wind turbine off-grid accidents. The voltage unbalance degree of the power grid needs to meet the requirements for the limit value of the voltage unbalance degree of the public connection point of the power syst...

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Problems solved by technology

[0003] In addition, according to the existing technical design specifications, overhead transmission lines with a length of less than 100 kilometers are erected without transposition. Non-transposition of lines will cause unbalanced impedance parameters of transmission lines, and different outputs of wind turbines will also affect the voltage of wind farms. Balance

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