Novel coordinated control strategy of urban DC distribution system for large-scale loads reduction

Abstract

In order to improve the load characteristics of urban power grid in China, the measure of shaving large-scale controllable loads (LSCLs) has been carried out in the peak load period which causes the fluctuations of distribution system's voltage and frequency. On the other hand, more and more decentralised rooftop photovoltaic systems (RPSs) have been employed in Chinese cities, whose grid-connected converters furtherly increase the difficulty of voltage and frequency stability control of distribution system. This study proposes a novel coordinated control strategy for the urban DC distribution system, which includes both distributed RPSs and LSCLs. The virtual synchronous motor-based control is innovatively applied to the rectifier of the DC distribution system in the coordinated control strategy. Based on the coordinated control strategy, the equivalent model of the DC distribution system is established in the form of ‘the prime mover–the generator–the variable load’. The LSCLs reduction has effects on the voltage and frequency of the DC distribution system. The simulated results show that the effects are effectively restrained by adopting the proposed control strategy.

Keywords

• power grids
• synchronous motors
• machine control
• photovoltaic power systems
• voltage control
• frequency control
• stability
• LSCLs
• China
• voltage control
• large-scale controllable loads
• urban power grid
• load characteristics
• large-scale loads reduction
• prime mover–the generator–the variable load
• virtual synchronous motor-based control
• distributed RPSs
• urban DC distribution system
• novel coordinated control strategy
• frequency stability control
• decentralised rooftop photovoltaic systems
• peak load period