Yu Qingguang

The asymmetric control strategy of ASVG

The ASVG (advanced static VAr generator) system with high power thyristor GTOs, is an important device in a FACTS (flexible AC transmission system). The research into asymmetric control of an ASVG takes an important role in reforming of the power net and improving its technology in the 21/sup st/ century. The paper presents a control strategy which is based on fuzzy-self-study control theory, which accomplishes the corresponding control with a multi-object in a nonlinear ASVG system.

Research for power load redistribution according to optimized strategy

In response to the three-phase unbalancing problem and for alternative solution to traditional manual operation, the author has proposed new method to achieve optimized load-distribution. The load redistribution device which operates based on the switch-matrix has the ability of plugging available loads into any one of the three phases without cutting down the power supply. The goal of calculating perfect load distribution pattern is achieved by a nonlinear 0–1 Integer Programming method which will be under comprehensive discussion. In the end, as well as the simulating result, prototype of a 60kVA device is given. This solution is easy to understand, simple to implement as well as reliable for practice.

Three level high voltage VSI adjustable speed IM drive system with IGCTS

In this paper, a three level high voltage VSI (voltage source inverter) adjustable speed IM (induction motor) drive system with IGCTs (integrated gate commutated thyristors) is developed. Two IGCTs are in series connection in each cell of the inverter in order to obtain a 6 kV high voltage output. The DSP (data signal processor) with FPGA (field programming gate array) controller is adopted to fulfill an optimized constant V/Hz control strategy. SHE-PWM (selective harmonic eliminated)-(pulse width modulation) method is carried out to keep sine wave output.

Failure analysis of IGCTs (5SHX 08F4502) in series connection in three level VSI

IGCTs (integrated gate commutated thyristors) was developed by ABB to be widely used in high voltage converters. IGCT also has been adopted in series to get higher output voltage of the converters. In this paper, failure analysis of IGCTs in series connection in three level VSI (voltage source inverter) was put forward, we share our experience, and discuss how to make full use of IGCTs.