Method for parallel operation control suitable to be used for microgrid inverter

Abstract

The invention discloses a method for parallel operation control suitable to be used for a microgrid inverter. The method comprises: step 1, adding virtual impedance in a voltage and current loop of conventional droop control; step 2, through measuring output voltage and current values of a micro power source, obtaining average active power and average reactive power; step 3, obtaining output frequency and voltage of the micro power source; step 4, comparing the output voltage, frequency, and reactive power of the micro power source with corresponding reference values, to obtain respective difference values; step 5, obtaining required compensation values of voltage, frequency, and reactive power; step 6, obtaining compensated frequency and voltage; step 7, inputting the compensated frequency and voltage to a voltage and current double-loop controller, and finally the frequency and voltage are maintained at rated values, the reactive power is distributed rationally. The method realizes technical effects of improving electric energy quality and rationally distributing reactive power, and distribution precision of the reactive power is relatively high.

Description

technical field [0001] The invention relates to a control method in the field of micro-grid, in particular to a control method suitable for parallel operation of micro-grid inverters. Background technique [0002] In order to solve the energy crisis and environmental pollution problems, renewable energy and distributed generation are widely used. The microgrid is composed of distributed generation (distributed generation, DG), energy storage device, energy conversion device, protection device and load and other equipment. It operates in grid-connected and island modes. Distributed power sources such as wind power generation, photovoltaic power generation and fuel cell power generation are connected to the grid through the inverter interface. Voltage and frequency are stable. [0003] Droop control does not require communication lines and has plug-and-play features, and is widely used. Traditional droop control adjusts the output voltage amplitude and frequency of each inver...

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Problems solved by technology

[0018] The invention provides a control method suitable for the parallel operation of microgrid inverters, which solves the problem that the existing droop control method cannot realize reactive power equalization and cause reactive power circulation; when the load power fluctuates greatly, the traditional droop control will There is a large deviation between the voltage and frequency of the microgrid and the rated value, which affects the power quality of the grid, and the technical problems of low reactive power distribution accuracy have achieved improved power quality, high reactive power distribution accuracy, and load power. When the change is large, the voltage and frequency of the microgrid can still be maintained at the rated value; when the line impedance between the DG unit and the common connection point is different, the technical effect of reasonable distribution of reactive power can also be achieved

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