Photovoltaic virtual synchronous generator control strategy of two-stage photovoltaic power generation system

Abstract

The invention discloses a photovoltaic virtual synchronous generator control strategy of a two-stage photovoltaic power generation system. A control strategy combining photovoltaic array virtual impedance characteristic disturbance and flexible power point tracking control is adopted in a preceding stage DC / DC link, when the illumination condition changes, a photovoltaic array stable working pointis positioned according to the supply and demand balance relation of the source power and the load power, and the voltage of a direct current bus is kept stable. An improved virtual synchronous generator control strategy based on preamble differential control is adopted in a post-stage DC / AC link, and system power frequency oscillation in the transient transition process is restrained.

Description

technical field [0001] The invention belongs to the technical field of distributed photovoltaic power generation control, and in particular relates to a photovoltaic virtual synchronous generator (PVVSG) control strategy of a two-stage photovoltaic power generation system. Background technique [0002] With the rapid development of the economy, the demand for energy in social production is increasing, the traditional fossil energy is decreasing, the environmental pollution is becoming more and more serious, energy and environmental problems are becoming more and more apparent, and the development of green renewable energy to replace fossil energy has become an energy source. inevitable trend of development. [0003] As a typical green renewable energy, solar energy can solve the energy crisis caused by the depletion of traditional fossil energy, and photovoltaic power generation is currently a major form of solar energy development and utilization. The output of photovoltai...

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Problems solved by technology

However, MPPT control always keeps the photovoltaic array at the maximum power output state regardless of the power demand of the external load. In the case of high penetration of photovoltaic power generation, it is easy to cause excess power in the system, thereby causing frequency instability of the power system and other power quality problems. question

[0004] The distributed photovoltaic inverter itself does not have rotational inertia and damping. When its penetration rate to the grid is high, it is not conducive to maintaining the stable operation of the power system.

CVSG control introduces virtual inertia and damping control to the post-stage DC / AC link of the two-stage photovoltaic power generation system, which is conducive to improving the operation stability of the power system in the case of high penetration of distributed photovoltaic power generation, but the photovoltaic inverter based on CVSG control The converter is prone to power fluctuations in the transient process

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