特高压直流输电系统在受端交流故障情况下的换相失败仿真结果有时会与实际运行情况有所差异,其原因之一在于仿真模型没有计及实际工程中使用的换相失败预测控制.在阐述特高压天中直流工程发生的两起特殊事件的基础上,详细分析了换相失败预测控制模型对特高压直流仿真结果的影响,通过搭建包含换相失败预测控制的直流输电模型对这两起事件进行了准确的仿真反演,发现换相失败预测控制在交流系统励磁涌流下会频繁动作,造成直流功率波动,并提出了能躲过励磁涌流的换相失败预测控制改进措施,仿真验证了该改进措施的有效性.

The testing method of actual clock-synchronism precision for the electric power automation equipments has became a important research item along with the widespread application of GPS synchronous clock in electrical power system.A portable synchronous clock is developed based on high precision GPS receiver and Field-Programmable Gate Array(FPGA) technology.This paper describes the design principle and application methods of this device.This device can record the absolute occurring time of external event and output pulse according to the setting time.Its power supply is rechargeable battery.This device can be applied to the clock-synchronism precision test for microcomputer-based protection,fault recorder and so on.It has the characteristic of high precision and good practicality.

Based on power-frequency varying vector method and parallel compensatory voltage lift technology, a new approach to measure transmission-line parameters, that can resist interference voltage comprehensively, is proposed. As for the proposed method, using the π-shape model for one-terminal measurement and taking distributed parameter characteristic of transmission line into account, the interaction between impedance and capacitive reactance of transmission line can be determined by use of one-terminal measured data. In the proposed method, the variance coefficient is taken as the index to judge whether the measured result is creditable. Actual measured results and calculation results of power-frequency parameters of UHV AC transmission line show that the proposed method is feasible and effective.

Considering the running performance of 500kVar/10KV SSSC,the author has introduced one full digital control system.The control circuit of high potential and design scheme of valve base electronics are both presented,in addition,the working principle and component of unit controller are analyzed in detail,the structure and function of valve base electronics are also given in this paper.

Based on the existing model for turbines and the governing systems,this paper reckons in pure time delay and makes the model more effective.The paper presents parameters measurement and data processing method,and gives a simulating error standard.With integral analyzing program for electric power system,simulation study has been completed.The results show that equivalent over-modulated coefficient of HP cylinder power is related to running conditions.The conclusions are reasonably useful.It is significant for measurement to study the model, method and simulation.

The photoelectric firing and monitoring system of industrial sample 500kvar/10kV SSSC are introduced.According to SSSC running performances,the unit controller is established through the analysis of energy getting methods of high potential circuit and the research on IGBT driven circuit.The generation way of driven pulses is obtained by analyzing the carrier wave phase-shift PWM.The modulation board is designed.The experimental results prove that this system is reliable.

This paper introduces the main structure of 500kVar/10kV static synchronous series compensator model machine. Based on PSCAD/EMTDC,the electromagnetic simulation model is proposed. Taking practical environment of the model machine as background, it approves the rationality of parameter design for equipments such as low-pass filter, coupling transformer, DC capacitor and so on. The transient phenomenon during operational pattern switch is analyzed. The capability of DC voltage regulation and dummy bus voltage regulation is validated in this paper. These studies provide theories for the development of model machine.

Residential fan loads such as electric fan, oil-smoke absorbing fan and so on, which are rotating devices though, and the transient process of which is very short, can be treated as static loads in conventional stability analysis of electric power system. This paper describes the static load models of fan loads by test results.

A mathematical model of single-phase capacitor run asynchronous motor, considering saturation characteristics of the motor, is presented in this paper. The experimental method and algorithm for testing and measuring the parameters of this kind of loads are systematically proposed. Model parameters of clothes washer type motors could be gained by experiments. The model and its parameters provide the foundation for the analysis and study of power system stability.

The article has done some research related to residential heating and wetting devices, which has built static load model. This article addressed second-step approaching arithmetic based on dispersing Fourier transform first time that established corresponding static load model, especially for external characteristic load of devices such as induction cooker, PTC warming fan andmicro-wave oven.

This paper presents the basic working principle and electrical circuit structure of switch power supply firstly.Based on that,static load model,which is related to electronic devices such as computers and TVs and so on,has been established through the experimental research.The conclusion drawn from the paper provides the proof for analysis and calculation of power system stability.

本文针对常用的照明用电设备包括白炽灯和气体放电灯,进行了试验研究。在此基础上,采用最小二乘法建立了照明负荷随电压变化的静态负荷模型。该类负荷模型为电力系统负荷集结及等值,进而为电力系统的稳定分析和研究奠定了基础。

Due to the separate phase control capability, low output current harmonics and fast response characteristics, cascade inverters based STATCOM is suitable for balancing compensation of 3-Ph unbalanced load. Main circuit configuration and integrated voltage-reactive power control scheme for balancing compensation with cascade inverters based STATCOM is proposed. The 3-Ph compensation current is obtained through vector transform with symmetrical weight method. The single phase reactive power is calculated with single phase instantaneous reactive power concept. Selective harmonics eliminated PWM (SHE-PWM) is employed to ensure that the THD of output current is less than 5% and the DC voltage is controlled. Simulation results verify the effects of the fast response of output reactive power for balancing the unbalanced load.

采用特征值及灵敏度分析技术,给出一种发电机降阶前后保持敏感振荡模式特征值实部不变的等效异步阻尼系数的算法.算例表明由该算法求得的等效异步阻尼系数,可准确描述阻尼绕组对电力系统稳定的作用.

DWK-3型变电站电压无功调节控制装置的研制,填补了河南省空白,其抗谐波功能、无时钟误差逆调压功能等具有国内领先水平.在论述装置的研制及其功能和技术特点的同时,还介绍了部分单位采用此装置后的应用效果,可预测其装置应用前景是无量的.

To improve the stability of power transmission system in He'nan Province, He'nan Electric Power Company and Tsinghua University have jointly investigated and developed ± 20 Mvar STATCOM employing GTO inverters. The STATCOM consists of four six-pulse voltage source inverter units rated 5 MVA each which use 48 GTOs rated 4. 5 kV/4 kA each to eliminate the 12 k ± 1 (k=1, 2, 3⋯)order harmonic components in the output voltage. A new type of GTO overcurrent protection. GTO turn-off low loss snubber circuit and a new method of suppressing DC over-voltage are proposed. The controller adopts a duplex system. Its functions, including sampling, control calculation and pulse generating, are all implemented with high-speed digital processing method based on 32-bit TMS320C31 DSP chip. The STATCOM has been installed in a 220 kV substation and has been put into operation successfully since April 1999. The field tests were carried out to verify the performance and the long-term reliability of the installation. The outline, technical features and field test results of the ±20 Mvar STATCOM are given. This project is the original Power Ministry Science and Technology Key Project.

The application background of ± 20 Mvar STATCOM developed jointly by He'nan Provincial Electric Power Company and Tsinghua University is described. And the fundamental principle and the overall scheme of designing large capacity STATCOM are outlined. Moreover, the connection between ±20 Mvar STATCOM and the system. together with the configuration of STATCOM and the design principle are also described. This project is the original Power Ministry Science and Technology Key Project.

This paper analyzes the generation of over-voltage V1, V2 and V3 during the turnoff of gate turnoff thyristor (GTO) and proposes a measure to decrease the overvoltage. Analyses of the features of conventional RCD snubber circuits and three kinds of low-loss snubber circuits are used to develop the snubber circuit for 4.5 kV/4 kA GTOs in a ±20 Mvar static synchronous compensator (STATCOM) installation. Experimental results demonstrate that the proposed snubber circuit is very effective for large capacity two-level GTO inverters.

This paper analyzes the generation of over voltages V 1 , V 2 and V 3 during the turnoff of gate turn off thyristor (GTOs) and proposes measures to decrease the over voltages. Analyses of the features of conventional RCD snubber circuits and three kinds of low loss snubber circuits are used to develop the snubber circuit for 4.5kV/4kA GTOs in a ±20Mvar static synchronous compensator (STATCOM) installation. Experimental results demonstrate that the proposed snubber circuit is very effective for large capacity two level GTO inverters.

An approach controlling the triggering pulse of GTOs of the advanced static var generator (ASVG) to generate a negative sequence voltage component while generating positive sequence voltage to counteract the system negative sequence component in order to suppress the negative sequence current through ASVG caused by system negative sequence voltage is presented. An algorithm to control the triggering pulse of ASVG is proposed based on modelling ASVG with the function of switching method. ASVG can operate normally and not overcurrent under a 15% negative sequence voltage component in the system voltage with this control algorithm. Simulation results show that the analysis and algorithm are correct.