Microgrid system with asymmetric nonlinear load and power balance control method

Abstract

The invention discloses a microgrid system with an asymmetric nonlinear load and a power balance control method. The system includes a plurality of parallel DG units and line impedances respectively connected to each DG unit. The line impedance is connected to the microgrid through a PCC point. On the power grid bus, the three-phase balanced resistive load, asymmetric linear load and diode rectified nonlinear load of the load unit are all connected to the microgrid bus through the PCC point, and the microgrid bus is also connected to the positive sequence for measuring the fundamental voltage of the PCC point. , negative sequence component and harmonic component measurement module, the microgrid bus is connected to the 10kV main grid through static switches and transformers in turn. The invention utilizes the selective virtual impedance based on the virtual fundamental wave positive sequence, negative sequence impedance and virtual variable harmonic impedance to realize the reactive power and harmonic power balance of the microgrid, and the harmonic and unbalanced voltage compensation controller can realize unbalanced The equal sharing of balanced power and harmonic power solves the problem of microgrid harmonic and voltage imbalance.

Description

technical field [0001] The invention belongs to the technical field of new energy distributed power generation and micro-grid control in power systems, and relates to a micro-grid system with asymmetric nonlinear loads and a power balance control method, in particular to an island with asymmetric nonlinear loads Unbalanced reactive power and harmonic power balance control method for microgrid. Background technique [0002] The widespread application of new energy distributed generation (Distributed Generation, DG) systems such as photovoltaic power generation and wind power generation has made the microgrid system based on distributed power sources, energy storage devices, loads and control devices an important part of the smart grid. Different from the traditional distribution network, the microgrid system can work in both grid-connected and islanded operation modes. In the island mode, the microgrid system needs to realize power sharing between DG units. However, the powe...

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Problems solved by technology

[0004] In summary, the existing microgrid control technology mainly studies the single case of linear symmetric load or nonlinear load, and there is no report on the case of asymmetric nonlinear load and inconsistent line impedance.

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