Low-voltage crossing method of two-stage type photovoltaic grid connected system of variable power tracking path

Abstract

The invention discloses a low-voltage crossing method of two-stage type photovoltaic grid connected system of variable power tracking path, which belongs to the field of new energy electric power system and micro power grid technology. Under the prerequisite that the original configuration of a two-stage three phase photovoltaic grid connected system is not changed and no auxiliary device is added, the power tracking path can be adjusted through the feed-forward control of the falling amplitude of voltage, the voltage at the photovoltaic cell end can be changed in a real-time manner, and the output of the photovoltaic cell power can be rapidly and effectively controlled, and the balance of power at two sides of an inverter can be realized. Through the cooperative control with a grid connected inverter, it can be guaranteed that under the prerequisite that the grid connected output of current of the inverter is not out of limit, active power and reactive power can be provided for the power grid as more as possible, the recovery of power grid voltage can be supported to the most extent, and the zero-voltage crossing of the photovoltaic grid connected system can be realized. Comparedwith the conventional control method, the invention is advantageous in that no additional device is required; safe and stable running of the system can be realized; the cost of the photovoltaic powergeneration system can be reduced, and practicality is better.

Description

technical field [0001] The invention belongs to the technical field of new energy power systems and micro-grids, and in particular relates to a low-voltage ride-through method for a two-stage photovoltaic grid-connected system with variable power tracking trajectory. Background technique [0002] With the continuous expansion of the scale of photovoltaic grid-connected power generation, the impact of the safe and stable operation of photovoltaic power generation systems on the power grid cannot be ignored. When a short-term fault occurs in the power grid, the large-scale off-grid of the unit will seriously affect the stability of the grid voltage and frequency, threaten the safety and stable operation of the grid, and may even cause a partial grid collapse, causing a large-scale power supply interruption. Therefore, the grid requires Photovoltaic generator sets have a certain low voltage ride through (LVRT) capability like traditional conventional units. The national standa...

AI Technical Summary

Problems solved by technology

The traditional low voltage ride-through strategy usually keeps the photovoltaic cells always working at the maximum power point, and only improves the topology of the photovoltaic system or adds auxiliary equipment to consume excess active power during the fault, which is not only expensive but also has a negative impact on system stability. certain influence

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