A High Voltage Ride-Through Control Method for Two-Stage Photovoltaic Grid-Connected Systems

By adjusting the reactive current reference value in the two-stage photovoltaic grid-connected system, the problem of active power loss during high-voltage faults was solved, reactive power absorption and DC bus voltage stabilization were achieved, and the high-voltage ride-through capability of the system was improved.

CN115051411BActive Publication Date: 2026-05-26PANZHIHUA POWER SUPPLY COMPANY STATE GRID SICHUAN ELECTRIC POWER
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
PANZHIHUA POWER SUPPLY COMPANY STATE GRID SICHUAN ELECTRIC POWER
Filing Date
2022-07-15
Publication Date
2026-05-26

AI Technical Summary

Technical Problem

Existing high-voltage ride-through control strategies in photovoltaic grid-connected systems are costly and difficult to control, and result in severe active power loss during high-voltage faults, leading to high grid disconnection frequency.

Method used

A high-voltage ride-through control method for a two-stage photovoltaic grid-connected system is adopted. By controlling the downstream grid-connected inverter to continuously output the same active power as when there is no fault, and adjusting the reactive current reference value according to the voltage change at the grid connection point, reactive power is absorbed to stabilize the DC bus voltage and reduce the voltage at the grid connection point.

Benefits of technology

Without adding hardware circuitry, the high-voltage ride-through capability of the photovoltaic grid-connected system is improved, active power is kept stable, grid connection point voltage fluctuations are reduced, and the system's fault ride-through capability is enhanced.

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Abstract

This invention discloses a high-voltage ride-through control method applicable to a two-stage photovoltaic grid-connected system. When a voltage surge occurs at the grid connection point, this method controls the downstream grid-connected inverter to continuously output active power equal to the active power output when the voltage surge is not present, thereby maintaining the stability of the DC bus voltage. Simultaneously, it adjusts the reference value of the reactive current on the DC grid side of the downstream grid-connected inverter according to the voltage surge situation, thereby changing the reactive power output of the downstream grid-connected inverter to reduce the grid connection point voltage. The control method provided by this invention is a combined active and reactive power strategy. During high-voltage fault ride-through, it still controls the downstream grid-connected inverter to maintain an active power output substantially equal to that when the voltage surge is not present, improving the high-voltage ride-through capability of the photovoltaic grid-connected system without sacrificing active power, and without requiring additional hardware circuitry.
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