Research On A Novel Transformer-type Controllable Reactor

Controllable reactors (CR) are general FACTS (Flexible AC Transmission System) apparatus, which have been widely used for regulating reactive power, stabilizing voltage and improving the electrical load character in the power system. In this dissertation, based on the comprehensively summarizing of the present development reactance-controlled techniques and the existing research productions of ourselves project team, a novel CR of transformer type is brought up, which has more advanced performances and costs less. Emphasizing the practice, over-all analysis and introduction for a single-phase shunt apparatus is provided on model establishing, control strategies, prototype designing and application, which verified by the experiment results at the same time. For detail, the original researches of the author are listed as following:Generalizing and deepening of "CR based on transformer magnetic flux compensation" is supplied. The consistency of multiple-windings and single-winding structure for this CR is discussed; and common reactance-adjusting principle by control of "linear two-port network" is provided.By combination of "stepping" and "infinitive" regulating, a novel hybrid controllable reactor of transformer type is proposed. The principle and operating analysis is provided; as well as some key problems about reactance stepping regulated with switches are settled. The comparison between the old and new CR technique is offered, which approves that the former have less cost and far more outstanding performance.Designing calculation and realization approaches for the reactor entity of the new CR are discussed; and with the aiding of ANSYS software, a single-phase rated 6kV, 630kVA prototype is designed successful, and the expected and measuring values of the impedance parameters are approximate.Embedded analysis for the PWM (Pulse width modulation) inverter-control system of the apparatus is provided. First, based on the conventional triangular carrier current control method for voltage source inverter, the model of the control system is established, and the stability and power balance of it is studied. Then, two control strategies for the system are brought up: close loop control for both current and DC side voltage, also the close loop control for only current, meanwhile, feasibility, operating characters and working conditions of control strategies are analyzed. Last, the determinations of main circuit parameters for the control system are provided.The experiment for the prototype verify the feasibility of the whole theoretical analysis, designing and operating schemes, as well as the excellent characteristics of the novel controllable reactor such as high control accuracy, little harmonic, fast response, wide continuous-adjusting range, etc.Some work of the engineering development for the CR applying in automatic tuning ASC (arc-suppression coil) is introduced. Some new opinions are offered about ASC devoting and exiting operation, value setting of initial reactance, etc: a novel method for measuring capacitive current and distinguishing high-resistance grounding of distributing network is presented, together, a adapting signal signal-processing algorithm is put forward, comparing to the traditional schemes, the new method has merits such as more real-time, accurate, and convenient. The researching progress of prototype is reported, and the experiment results declare the superiority of the new controllable reactor technology too.