Research On Advanced Reactive Compensation Equipments And Their Coordinated Operation In Distribution Power System

The nonlinear and impulse loads have been increasing rapidly in low voltage distribu-tion grid of our country that results in the voltage deterioration of the power system. Since the consumers in distribution network have been using a great amount of precise electronic equipments, their requirements about stability of system voltage become stricter. At the same time, there is an enormous gap between our country and other developed countries from the level of power factor to the degree of reactive power compensation. There is a se-rious demand for adding a number of reactive power compensation equipments which are intelligent, dynamic and continuous so as to reduce the active power and reactive power losses in power transmission, improve voltage quantity in distribution network.SVC and D-STATCOM are the most two important shunt FACTS devices for reactive power compensation at present. Compared with traditional ones, they have some significant advantages in the aspects of controllability and response speed, etc. On the other hand, the cost of power electronics decreases successively with the technology development. There-fore, they have been gotten more and more attentions and applications. Their principles and key technologies have been analyzed in this paper. The control methods based on fuzzy PI and intelligent PID have been introduced for the special hardware platforms. The results of simulations and experiments have shown that the dynamic performance and robustness of devices have been improved greatly by using the proposed methods. These achievements afford useful reference for the application of these equipments.Predictably, with the widespread use of FACTS devices for reactive power compensa-tion and some special requirements, the situation that both SVC and STATCOM are used in the same bus would spring up frequently. The cases are analyzed in detail and the results of simulation show that the value of connected reactance and capacity of short circuit are the two key elements of interactive influence between them. Fuzzy predictive multivariable coordinated control method is present to suppress the bad interactive influence and realize optimal operation. The results of simulation show that even at the extreme case where the values of two elements mentioned above are low, the method can still play a role to sup-press the interactive influence between them and improve the system performance.