Energy storage inverter virtual synchronization method and system for adaptive optimization of grid strength

Abstract

The invention provides an energy storage inverter virtual synchronization method and system for adaptive optimization of power grid strength. The method includes data acquisition, power calculation, output calculation of a virtual speed governor, output calculation of a rotor mechanical equation, power grid impedance calculation, damping value spline interpolation fitting and parameter updating. Improvement is made on the virtual damping link. By introducing differential into the virtual damping link, the virtual damping has no effect on the virtual difference coefficient, and the steady stateerror of the primary frequency modulation of a virtual synchronous machine is eliminated. Meanwhile, a first-order inertia link is introduced to improve the stability of the system. Adaptive parameter optimization control is carried out on the virtual damping link. The impedance of the power grid is detected online by harmonic injection, and the parameters of the damping link are adjusted onlineaccording to the detected impedance of the power grid and an adaptive formula, so that the virtual synchronous machine can have better response characteristic before and after the change of power gridstrength.

Description

technical field [0001] The invention relates to the technical field of power generation and transformation, in particular to a method and system for virtual synchronization of energy storage inverters for self-adaptive optimization of grid strength. Background technique [0002] New energy power generation is integrated into the grid through power electronic converters. Due to the lack of damping and inertia similar to synchronous machines, it cannot independently respond to power changes in the power system, making the high proportion of new energy connected to the grid a threat to the safe and stable operation of the power system. Therefore, some scholars have proposed a control method that uses an inverter to simulate the characteristics of a synchronous motor. By increasing the damping, inertia and frequency modulation and voltage regulation characteristics, the operation stability is improved. This control is called virtual synchronous generator control (VSG, virtual syn...

AI Technical Summary

Problems solved by technology

[0003] The core of virtual synchronous control lies in virtual inertia link and virtual damping link. The first-order inertia link formed by virtual damping and virtual inertia used in traditional virtual synchronous technology is an open-loop control, which leads to mutual coupling between virtual damping and virtual adjustment coefficient, making The actual virtual adjustment coefficient is significantly smaller than the design value, which leads to excessive response of the virtual synchronous generator when the grid frequency fluctuates, causing adverse consequences

However, when this steady-state error is eliminated only by transforming the virtual damping link, the parameters of the virtual synchronous machine will not be unified under the strong network and the weak network, resulting in poor response of the virtual synchronous machine.

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