Virtual synchronous generator control method suitable for photovoltaic grid-connected system

Abstract

The invention relates to a virtual synchronous generator control method suitable for a photovoltaic grid-connected system. According to the method, modulated waves required by the generation of PWM pulses are controlled; the modulated waves are compared with carriers, so that PWM pulse signals are generated to control the switching on and switching off of the switch tube of a three-phase bridge DC / AC inverter; and the VSG (virtual synchronous generator) control of the photovoltaic grid-connected system can be realized. Experimental simulations show that the method of the invention can effectively control the DC / AC inverter in the photovoltaic grid-connected system, has good effects in maintaining power balance, voltage and frequency stability of the system and can improve the transient stability and dynamic quality of the photovoltaic grid-connected system.

Description

Technical field [0001] The present invention relates to distributed power generation grid-connected control, in particular to a virtual synchronous generator (referred to as VSG) control method suitable for photovoltaic grid-connected systems. Background technique [0002] Energy is an important factor that sustains human survival and social development. While playing an indispensable positive role, it also causes problems such as energy shortages and fossil energy pollution. In order to alleviate these problems, in recent years, the use of renewable energy such as solar energy and wind energy has gradually received attention from various countries and has been vigorously developed. Among them, solar photovoltaic power generation accounts for a considerable proportion. As of 2016, the world's cumulative installed photovoltaic power generation capacity has exceeded 300GW, and my country has ranked first in total photovoltaic installations for four consecutive years since 2013. As ...

AI Technical Summary

Problems solved by technology

This method has high requirements on the accuracy of the model, and it is difficult to guarantee the control effect when the system structure or parameters are uncertain.

[0005] For the distributed inverter power supply, the traditional control strategy is a current-based control strategy based on the decoupling of the rotating coordinate system. In the state, when using this control algorithm, the dynamic characteristics of the DC / AC inverter are poor

In addition, the traditional decoupling control generally controls the system by approximating the system to be linear. In fact, the mathematical model of the distributed DC / AC inverter presents nonlinear characteristics. Such approximation will undoubtedly affect the control effect.

Images