Research On AVC Reactive Power Optimization Considering AC/DC Hybrid Grid

Compared with the high-voltage AC transmission system, high voltage direct current transmission technology has some distinctive features, such as transmission capacity, transmission loss and the power is easy to control, and so on. For this reason, in recent years an increasing number of HVDC connected to the grid, including some high voltage direct current lines to form AC/DC interconnected power system. Meanwhile, automatic voltage control (AVC) as an important means of control in power system, is very important for the maintenance of power system voltage stability. Because HVDC can serve as an important means of AVC (such as HVDC reactive power compensation devices), but also put forward new requirements for AVC, so it's very necessary to research on reactive power optimization considering AC/DC hybrid grid. Therefore research in this paper studies the problem and the main contents and results are as follows:1. Based on the modal analysis, dividing the control area based on the sensitivity relationship between reactive power and node voltage, making the nodes in the same area have similar voltage change characteristic. Laid a foundation for regional AVC control. Presenting a new selecting strategy for leading nodes. Considering introducing maximum reactive offset factor and maximum voltage offset factor to the object function. Compared with the traditional selecting strategy, the strategy presented in this paper can avoid nodes'reactive power and voltage changing significantly in some cases.2. Building the reactive power optimization model of AC/DC hybrid system, considering that HVDC voltage stability has an important significance for the stable operation of HVDC, so regarding maintaining the HVDC voltage stability as one of AVC control objectives, will help to improve the stability of HVDC, and solving the model using PSO algorithm. The simulation results indicate that the maintenance of the stability of DC placement voltage has an important impact on improving the stability of HVDC.3. Considering HVDC side reactive power compensation devices can be involved in reactive power optimization, reactive power compensation equipment can be used as one of the reactive power optimization control means, solving the test cases with Particle Swarm Optimization algorithm. The results indicate that the voltage quality of the entire system can be improved when the reactive compensation devices participating in the AVC control.