Synchronous pulse-based multi-converter control method

Abstract

The invention provides a synchronous pulse-based multi-converter control method, which comprises the following steps of: 1) selecting any converter from a microgrid as a master converter, periodicallychanging the phase of the master converter by power frequency, and taking the rest converters as slave converters; 2) when the phase of the main converter is within [theta0, theta0 + delta theta], continuously sending a synchronous pulse signal out; 3) enabling the slave converters to set the phases of the slave converters to realize phase synchronization among the converters. Compared with a traditional phase locking method, the method has the advantages that the problem that the phase locking performance is reduced due to three-phase imbalance of a synchronous signal source, high harmonic content, errors of a voltage sensor and the like is solved; according to the method provided by the invention, a phase gradual approximation method is adopted when the slave converter performs synchronization operation, and the phase is not directly assigned, so that the synchronization of the phase is ensured, and the circulation problem possibly caused by direct assignment is avoided.

Description

Technical field: [0001] The invention relates to the field of converter control, in particular to a multi-converter control method based on synchronous pulses. Background technique: [0002] In recent years, the renewable energy industry has continued to grow, its share in the electricity market has gradually increased, and it has entered a stage of large-scale development. Due to the decentralized nature of renewable energy, the traditional mode of centralized power generation and long-distance power supply in large power grids has shown certain limitations. Compared with the traditional large power grid, the microgrid has high reliability, low power investment and short construction period. [0003] The flexibility and reliability of the microgrid is based on its stable control. From the perspective of the system level, the microgrid generally adopts a hierarchical control mode based on multi-agent technology, with a central controller, which is divided into two or three...

AI Technical Summary

Problems solved by technology

When droop control is used, each converter is equal in status and has the output characteristics of a voltage source. Only local information is used for control, and the work reliability is high, but there are still many problems: the line impedance from the converter to the bus is not It is purely inductive or purely resistive, so the active power and reactive power cannot be completely decoupled and controlled; the droop control is a differential adjustment, and there are deviations in the frequency and amplitude of the bus voltage; the difference in line impedance prevents the power from completely following the set droop Coefficient distribution; improper design of droop coefficient will also cause system instability

However, the three-phase unbalance of the synchronous signal source and the error of the voltage sensor will lead to the degradation of the phase-locking performance and the inability to stably control the phase

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