Inverter parallel operation optimization control method

Abstract

The invention provides an inverter parallel operation optimization control method. The method includes acquiring the rated capacity of each inverter in the parallel inverter system and the total load power factor angle of the parallel inverter system, determining the corresponding virtual impedance and sagging coefficient for each inverter according to the rated capacity and the total load power factor angle, determining the phase angle of each inverter based on the sagging coefficient, and then setting the same voltage amplitude for each inverter, determining the command voltage based on the voltage value, the virtual impedance, the phase angle, and the inverter output current, and controlling each inverter to output the active power and the reactive power according to the corresponding command voltage. The virtual impedance and sagging coefficient are determined by integrating the rated capacities of the inverters and the total load power factor angle of the parallel inverter system to realize the reasonable distribution of the active power and the reactive power of the inverters, the control effect of the inverters is optimized to reduce the voltage deviation, and the quality of the output energy of the inverters and the normal running of the user equipment or electric appliances are guaranteed.

Description

technical field [0001] The invention relates to the field of power electronic device control, in particular to an optimal control method for parallel operation of inverters. Background technique [0002] The inverter is a converter that converts DC power (battery, storage battery) into AC power (generally 220V, 50Hz sine wave). In the microgrid and UPS parallel redundant system, there are multiple inverters running in parallel. [0003] The control methods for parallel operation of parallel inverters mainly include: PQ control, constant voltage and constant frequency control, and droop control. Among them, droop control is a method of controlling the inverter by simulating the droop external characteristics of synchronous generators in the traditional power system. method. Such as figure 1 As shown, the main circuit of the circuit structure of the inverter adopting droop control in the parallel inverter system is a three-phase full-bridge circuit. The inverter output uses...

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Problems solved by technology

[0004] However, due to the difference in the characteristics of the inverter itself, the difference in output power of multiple inverters in parallel operation will decrease with the increase of frequency and amplitude droop coefficient, but with the increase of droop coefficient, the output power of multiple inverters will decrease. The voltage deviation between inverters will also increase accordingly. The introduction of virtual impedance will make the voltage deviation more prominent. When the voltage deviation exceeds the specified value, the control effect of the inverter will be deteriorated, resulting in the The power quality is degraded, which affects the normal operation of user equipment or electrical appliances connected to the inverter

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