Photovoltaic power generation system low voltage ride through reactive control method

Abstract

The invention relates to a photovoltaic power generation system low voltage ride through reactive control method. The method comprises the following steps: (1) calculating and storing output active power Ppre of a photovoltaic grid-connected inverter before faults; (2) detecting whether actual voltage E of a grid-connected point drops, and 0.2EN<=E<=0.9EN, EN being nominal voltage of the grid-connected point, if yes, executing step (3), if no, using a grid-connected control method when network voltage is normal to control; (3) switching the photovoltaic grid-connected inverter to a low voltageride through reactive control mode, specifically including (31) obtaining maximum active power Pmax the photovoltaic grid-connected inverter allows to output, (32) if Ppre<=Pmax, making the photovoltaic grid-connected inverter work in a MPPT mode, otherwise, making the photovoltaic grid-connected inverter work in a non-MPPT mode; (4) returning to the step (2) and executing in a looping manner. Compared with the prior art, the method makes use of capacity of the photovoltaic inverter to the maximum extent, investment of reactive equipment is saved, and resources are saved.

Description

technical field [0001] The invention relates to a technology for integrating a photovoltaic power generation system into a power grid, in particular to a low-voltage ride-through reactive power control method for a photovoltaic power generation system. Background technique [0002] Environmental and energy issues are becoming more and more prominent. The development and utilization of renewable green energy is an effective measure to solve the current environmental degradation and energy shortage. Photovoltaic power generation, as an important way of green energy development and utilization, has attracted the attention of countries all over the world, and the proportion of photovoltaic installed capacity is increasing. A large number of photovoltaic power generation systems are connected to the grid. The traditional method of quickly cutting photovoltaic power generation systems out of the grid due to grid failure can no longer meet the requirements. Suddenly cutting out lar...

AI Technical Summary

Problems solved by technology

Conventional voltage outer loop and current inner loop dual-loop grid-connected control strategy cannot achieve low-voltage ride-through when the grid voltage drops

When the grid voltage drops, due to the imbalance between the output active power of the photovoltaic array and the output power of the photovoltaic inverter, the current on the AC side of the photovoltaic inverter increases sharply, and the voltage on the DC side increases, which will burn the inverter components

In addition, when the power grid fails, reactive power compensation devices such as capacitors and SVC are usually connected to supplement the reactive power demand, ignoring the reactive power output capability of the photovoltaic power generation system itself, resulting in a waste of resources

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