Control method of virtual synchronous generator based on direct power control when grid voltage is unbalanced

Abstract

A virtual synchronous generator control method based on direct power control when the grid voltage is unbalanced. First, ROGI is used to obtain the positive sequence component of the grid voltage and grid-connected current, the instantaneous power output by the inverter, and the average instantaneous power; the average instantaneous power is used as feedback Using the traditional virtual synchronous control strategy to obtain the reference modulation signal in the αβ static coordinates; the vector proportional integral resonant controller is used to establish a direct power control loop, and the output instantaneous power is used as the feedback quantity. By setting different power command values ​​respectively, the direct power control loop is used The power control obtains the modified modulation signal; the reference modulation signal and the modified modulation signal are superimposed to obtain the final modulation signal, which is sent to the SVPWM modulation module to achieve two independent control goals of sinusoidal and balanced output current and constant output power without fluctuation. The invention retains the original control characteristics of the VSG, does not need a phase-locked loop, improves the dynamic response capability of the system, and is easy for engineering realization.

Description

technical field [0001] The invention belongs to the technical field of distributed power generation, and relates to a virtual synchronous generator control method when the grid voltage is unbalanced. Background technique [0002] The development of renewable new energy and the improvement of the utilization efficiency of renewable energy are the inevitable ways to solve human energy problems. Renewable energy needs to be connected to the grid through power electronic converters, with the goal of injecting maximum power into the grid. When the installed capacity of distributed generation is relatively low, the original traditional synchronous generators in the system can provide sufficient support for the power system, and the access of distributed generation units will not pose a threat to the stability of the power system. Since the distributed generation units interfaced with power electronic converters do not have the inertia and damping of synchronous generators, with t...

AI Technical Summary

Problems solved by technology

[0003] The distributed generation unit is installed at the end of the power grid, away from the main power network, the power grid is fragile, and the power grid environment is relatively complex, the grid voltage has high harmonic content and the grid impedance is large, and grid voltage imbalance faults are prone to occur

These non-ideal grid environments will directly affect the power quality and stable operation of virtual synchronous generators, and also have a negative impact on the safe and stable operation of the grid.

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