Situation descriptions:
Owning to the increase of types of distribution network loads, the power quality becomes worse, even some sensitive loads cannot work normally, therefore the utilities pay more and more attention on the power quality for users. At the same time, power quality is important for guaranteeing the safety and stability of power grid as well as economic operation. In response to the current urgent requirements of distribution network power quality control (low voltage qualification rate, high three-phase imbalance, large harmonic component, low power factor, and voltage flicker), Banner Electric, relying on network communication and automation control technology, realized a reliable technical foundation for real-time, automatic, and systematic power quality monitoring information management of the distribution network. Based on years of experiences in the research R&D and promotion of smart grid power quality control, power distribution automation, and informatization, Banner proposed a complete solution schemes for the distribution network power quality treatment. The proposal is aimed to realize dynamic fine management of power quality of the distribution network. Solutions: The stability of the 10kV distribution network is the basis for the stable power supply of the 0.4kV distribution network. Due to regional differences and natural factors, the 10kV distribution network has some power quality problems such as low voltage qualification rate and voltage flicker
Bona Electric employs a segmented installation of 10kV static var generator to realize short-time voltage fluctuation speed control, local reactive power balance and current harmonic filtering simultaneously; and uses 10kV line automatic voltage regulator to solve the long-term unqualified voltage problems caused by poor power supply network or too long power supply radius. However, the 0.4kV power supply network features high complexity and variability, as well as serious power quality problems like low voltage qualification rate, unbalanced three-phase current, large harmonic component, low power factor, and voltage flicker. Faced with above issues, Banner Electric offers a centralized + distributed management approach to achieve comprehensive management of 0.4kV power quality. The specific method is to install a power electronic three-phase imbalance automatic adjustment device with three-phase current unbalance adjustment, reactive power compensation, and harmonic current filtering on the low-voltage side of the transformer in the transformer area to achieve comprehensive treatment at the area; for the area with large unbalanced three-phase current, the three-phase imbalance adjusting device with phase-change switch is installed for troubleshooting; and for the too long power supply radius or too low voltage, the 0.4kV three-phase four-wire voltage regulator and 0.22kV single-phase voltage regulator are applied to ensure the qualified voltage rate. Each power quality control device on the 0.4kV side is interconnected with the intelligent integrated management device for the transformer area to realize the dynamic adjustment of the operating parameters and perfectly solve all the power quality problems existing in the distribution network.
Available equipment and system:
10kV static var generator (SVG); 10kV line automatic pressure regulator; Intelligent transformer area integrated management device; Power electronic three-phase imbalance automatic adjustment device (0.4KV); Three-phase imbalance adjusting device with phasechange switch; 0.4kV three-phase four-wire pressure regulator; 0.22kV single-phase voltage regulator; Distribution network power quality control software
