Coordinated Operation Control Strategy of AC/DC Hybrid Distribution System Based on Solid-state Transformer

doi:10.12204/j.issn.1000-7229.2023.04.012

Abstract

Abstract:

The AC/DC hybrid power distribution system based on solid-state transformer (SST) is of great significance for large-scale consumption of renewable energy. Reliable control strategy is the key to ensure stable operation of hybrid power distribution system. In this paper, the coordinated operation control strategy of AC/DC hybrid distribution system based on SST is proposed. The control strategy of “source, storage and load” in the subnet can realize the power balance in the subnet independently. The low-voltage level can maintain the low-voltage AC bus voltage and realize the mutual assistance of AC and DC subnets. The isolation level coupling medium-voltage DC bus and l low-voltage DC bus, support the medium-voltage DC bus voltage. Medium-voltage level can construct medium-voltage AC bus voltage, realize mutual support between low-voltage and medium-voltage levels, and adopt voltage-source output form when off-grid and grid-connected, without switching control strategy, and cooperate with pre-synchronization control to realize seamless switching between modes. RTDS simulation results show that the system can adopt a unified control strategy, and achieve power coordination and seamless switching between multiple modes in the AC/DC hybrid distribution system based on SST without communication, which verifies the effectiveness and feasibility of the proposed control strategy.

Key words: solid state transformer (SST), hybrid AC/DC microgrid, power coordination, no communication, seamless switch

CLC Number:

TM41

ZHANG Wenjie, Lü Shixuan, GAO Qixuan, ZHENG Lijun. Coordinated Operation Control Strategy of AC/DC Hybrid Distribution System Based on Solid-state Transformer[J]. ELECTRIC POWER CONSTRUCTION, 2023, 44(4): 103-112.

Figures/Tables 18

Fig.1 Topology of solid-state transformer

Fig.2 AC/DC hybrid power supply system based on SST

Fig.3 Control strategy of energy storage unit, photovoltaic unit and load in AC/DC subnet

Fig.4 Block diagram of the control strategy of low-voltage level

Fig.5 Block diagram of the control strategy of medium-voltage level and DAB

Table 1 Experimental parameters

Table 2 Description of working condition

Fig.6 Experimental waveforms under working condition 1

Fig.7 Experimental waveforms under working condition 2

Fig.8 Experimental waveforms under working condition 3

Fig.9 Experimental waveforms under working condition 4

Fig.10 Experimental waveforms under working condition 5

Fig.11 Experimental waveforms under working condition 6

Fig.12 Experimental waveforms under working condition 7

Fig.13 Experimental waveforms under working condition 8

Fig.14 Experimental waveforms under working condition 9

Fig.15 Experimental waveforms under working condition 10

Fig.16 Experimental waveforms under working condition 11

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