SVG control function and realization of modular multi-level DC ice melting device

Abstract

In recent years, transmission line icing caused by ice and snow disasters threatens the safe and stable operation of power system. Among the existing ice melting devices, the modular multilevel DC ice melting device has the characteristics of less harmonic content, small volume, simple switching mode, low failure rate and small power capacity, which has significant advantages in economy and technical feasibility. However, because the modular multilevel DC ice melting device is only used during the freezing period in winter, the problem of low utilization rate of the device is also prominent. In order to solve the problems of large volume, high harmonic content, high cost and low utilization rate in the operation of traditional DC ice melting device, this paper proposes a control function and implementation method of modular multilevel DC ice melting device based on SVG. During non-ice melting period, the control strategy can output or absorb reactive power according to the needs of the system to support the grid voltage and improve the utilization rate of equipment. This paper first analyzes the topology and working principle of the modular multilevel DC deicing device, then introduces the carrier phase shift modulation strategy of the modular multilevel DC deicing device, and puts forward the SVG control strategy of the modular multilevel DC deicing device under three-phase balanced and unbalanced conditions, so as to realize load dynamic reactive power compensation and grid voltage drop suppression, The reliability of the system is improved significantly. Finally, based on the above method, the Simulink simulation model is established to verify the effectiveness of the control strategy, and the simulation waveform is given for analysis.