Control device and method for improving stability of photovoltaic virtual synchronous machine system with small-capacity energy storage ratio

Abstract

The invention belongs to the field of new energy and the technical field of distributed power generation, particularly relates to a control device and method for improving the stability of a photovoltaic virtual synchronous machine system with a small-capacity energy storage ratio, and mainly relates to photovoltaic dynamic characteristic detection and photovoltaic virtual synchronous machine design. The device comprises a photovoltaic power generation system, a small-capacity energy storage device, an inversion device and a virtual synchronous machine device with DC end additional control. The power output end of the photovoltaic power generation system is connected with the small-capacity energy storage device and the inversion end of the inversion device, and then is connected with a power grid through the LC filter circuit and the line impedance. According to the invention, the phenomenon that the inverter fails to work due to sudden drop of direct-current voltage can be avoided; the problem that output active power and reactive power are affected by line impedance in inverter networking or grid-connected operation is solved, the problem that the load or the external environment cannot be predicted and controlled is solved, and the situation that the inverter fails to invert and is off-grid due to the fact that the voltage of the photovoltaic power supply is dramatically reduced and cannot return to a stable working area is avoided.

Description

technical field [0001] The invention belongs to the field of new energy and the field of distributed power generation technology, and particularly relates to a control device and method for improving the stability of a photovoltaic virtual synchronous machine system with a small-capacity energy storage ratio, and mainly relates to photovoltaic dynamic characteristic detection and photovoltaic virtual synchronous machine design . Background technique [0002] As the penetration rate of distributed power generation in the power grid increases, the excellent inertia and damping characteristics in the power system are gradually replaced, and the power system will be seriously threatened by low inertia and low damping. As a grid-connected inverter control method that simulates the external characteristics of synchronous generators, the virtual synchronous machine provides a new development direction for the grid-connected problem of distributed power sources. The virtual synchron...

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Problems solved by technology

However, the output of distributed photovoltaic power is easily affected by external environmental factors, and there are problems such as stable operation area and capacity limitation. The traditional virtual synchronous motor control strategy can easily make the output power of the inverter greater than the allowable upper limit of photovoltaic power output, making the photovoltaic The power supply enters the unstable working area, which may reduce the maximum output power or cause the inverter to crash

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