Microgrid seamless switching control system and method for voltage and current coordinated control

Abstract

The invention discloses a voltage and current cooperation control micro-grid seamless switching control system and a voltage and current cooperation control micro-grid seamless switching control method. When a micro-grid is in grid-connected operation, a basic voltage loop and an additional current loop simultaneously participate in adjusting cooperation control, and a controller works in a current source mode. In the seamless switching process of switching grid-connected operation into an island, output of the additional current loop is limited within a set range during detection of the island, and the basic voltage loop continues control. After the state of the island is detected, the additional current loop is switched off, the basic voltage loop individually works, and the controller is switched from the current source mode to a voltage source mode. In the seamless switching process of switching the island into grid-connected operation, the basic voltage loop and a phase pre-synchronization model controls voltage pre-synchronization, a PCC (program-controlled computer) point grid-connected switch is closed after grid-connected requirements are met, the additional current loop is closed again to work, output given current values of the controller are adjusted, the basic voltage loop and the additional current loop simultaneously work and perform cooperation control, and thecontroller works in the current source mode again.

Description

technical field [0001] The invention relates to the intersecting field of micro-grid operation and control and power electronics technology, in particular to a micro-grid seamless switching control system and method for voltage and current coordinated control. Background technique [0002] With the global environmental pollution and energy shortage, the research and application of renewable energy such as photovoltaics and wind power have been promoted. Microgrid is a very important way to absorb and accept these renewable energies. It connects distributed power generation units such as photovoltaics and wind power into the system, and configures energy storage units and protection devices. Through appropriate control methods, the entire system can be guaranteed. stable operation and utilize renewable energy to the greatest extent. The microgrid needs to ensure the normal operation of the two working modes of grid-connected and island. The control methods and structures of ...

AI Technical Summary

Problems solved by technology

Before the island is detected, the main inverter of the traditional control strategy still works in the current source mode, and the output power remains unchanged, so the voltage and frequency of the load will change suddenly due to the power imbalance

After the island is detected, the controller directly switches from PQ control to V / F control, and the inverter is controlled as a voltage source, but the hard switching of the control structure further deteriorates the voltage quality

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