电容式电压互感器介损的测试方法

介绍了电容式电压互感器(CVT)中电容器部分的介损和电容量现场测量方法，即采用正接法直接在电容器两端加试验电压的办法测量。克服了二次加压法现场试验比较烦琐、对试验人员要求比较高，以及由于二次加压不当造成互感器损伤等缺点。     

集合式电容器的缺陷分析处理

本文对一台绝缘油色谱异常的集合式电容器进行了分析,找出原因,提出解决方法,通过实践证明集合式电 容器运行中应增加绝缘油色谱试验项目。     

Integrated standalone hybrid solar PV,fuel cell and diesel generator power system for battery or supercapacitor storage systems in Khorfakkan,United Arab Emirates

Renewable energy resources play a very important rule these days to assist the conventional energy systems for doing its function in the UAE due to high greenhouse gas (GHG) emissions and energy demand. In this paper, the analysis and performance of integrated standalone hybrid solar PV, fuel cell and diesel generator power system with battery energy storage system (BESS) or supercapacitor energy storage system (SCESS) in Khorfakkan city, Sharjah were presented. HOMER Pro software was used to model and simulate the hybrid energy system (HES) based on the daily energy consumption for Khorfakkan city. The simulation results show that using SCESS as an energy storage system will help the performance of HES based on the Levelized cost of energy (LCOE) and greenhouse gas (GHG) emissions. The HES with SCESS has renewable fraction (68.1%) and 0.346 $/kWh LCOE. The HES meets the annual AC primary load of the city (13.6 GWh) with negligible electricity excess and with an unmet electrical load of 1.38%. The reduction in GHG emissions for HES with SCESS was 83.2%, equivalent to saving 814,428 gallons of diesel.     

Optimal capacitor placement for enhancing voltage stability in distribution systems using analytical algorithm and Fuzzy-Real Coded GA

Two algorithms for optimal capacitor placement, with a view to enhance voltage stability are introduced. In the analytical algorithm the nodes, whose voltage stability index values are lower than a threshold value, are ranked in ascending order as the candidate nodes for compensation. The additional reactive power compensation to be provided at a node is obtained by solving linearized VSI formula. The maximum compensation at each node is limited to the initial reactive power delivered by the respective node prior to compensation for avoiding over-dimensioning of the capacitor banks. However, capacitor placement based on voltage stability index has proven less than satisfactory and not always indicated the appropriate placement.As an alternative a fuzzy expert system is used for extracting suitability of capacitor location from power loss reduction index and improving the voltage profile within voltage constraints. A combination of fuzzy expert system for capacitor placement and real coded GA for capacitor sizing, with a view to enhance voltage stability is proposed for optimal capacitor placement. The result is enhancement of the overall system stability index and potential achievement of maximum net money savings due to power and energy loss reduction vs. expenditure in capacitors.The overall accuracy and reliability of the proposed Fuzzy-Real Coded GA algorithm has been validated and tested on 33-node radial distribution system. Comparison of obtained results with those in recent publications showed that the Fuzzy-Real Coded GA algorithm is capable of producing high-quality solutions with good performance of convergence, and demonstrated viability.     

Capacitor placement of distribution systems using particle swarm optimization approaches

Capacitor placement plays an important role in distribution system planning and operation. In distribution systems of electrical energy, banks of capacitors are widely installed to compensate the reactive power, reduce the energy loss in system, voltage profile improvement, and feeder capacity release. The capacitor placement problem is a combinatorial optimization problem having an objective function composed of power losses and capacitor installation costs subject to bus voltage constraints. Recently, many approaches have been proposed to solve the capacitor placement problem as a mixed integer programming problem. This paper presents a new capacitor placement method which employs particle swarm optimization (PSO) approaches with operators based on Gaussian and Cauchy probability distribution functions and also in chaotic sequences for a given load pattern of distribution systems. The proposed approaches are demonstrated by two examples of application. Simulation results show that the proposed method can achieve an optimal solution as the exhaustive search can but with much less computational time.     

一起变压器过励磁保护动作的试验及仿真分析

对一起由电容式电压互感器二次电压异常造成500k V主变跳闸的事件进行了研究和分析,对电容式电压互感器进行了故障模拟试验和仿真分析,找到了故障原因,并提出了运行维护的措施和建议。     

电容式电压互感器二次电压在线监测在故障检测分析中的应用

介绍了一起电容式电压互感器的底座上端发热故障案例,找出了电容式电压互感器出现该类故障的原因,提出了一种基于EMS系统的电容式电压互感器二次电压在线监测的方法。     

Pseudo-V2 control with adaptive compensation for fast-transient current-mode buck converter

A type of pseudo-V² control, with on-chip adaptive compensation to achieve fast transient (FT) response for current mode DC–DC buck converter, has been proposed and simulated using 0.18 μm CMOS technology in this paper. Based on a new on-chip capacitor multiplier, adaptive compensation is achieved by making the compensation capacitance to track the load current. The proposed pseudo-V² control utilizes the output ripple to determine the duty cycle during load transient. Thus the overshoot/undershoot voltage and the transient recovery time are effectively reduced. Simulation results demonstrate the transient ripple is smaller than 50 mV and the transient recovery time is shorter than 10 μs for a 450 mA load current step. The maximum power conversion efficiency is 94.6% at 1 MHz switching frequency when input and output voltages are 5 V and 1.8 V, respectively.     

无功控制在南桥换流站的应用

葛南直流控制保护系统在运行15年后进行了全面改造,无功控制有较大改进,根据优先级原则,防止部分交流滤波器组因故被切除后造成运行中的其它交流滤波器谐波过负荷,通过无功控制保证系统与换流站之间交换的无功功率在现有电网允许的范围内,通过投/切交流滤波器维持稳态交流电压在过压保护动作的水平以下,大大提高了交、直流输电系统的可靠性。     

电力电容器不锈钢外壳搪锡工艺探讨

通过对不锈钢搪锡的特点分析,介绍了电容器不锈钢外壳套管孔搪锡使用的焊剂配制,提出了用磷酸代替盐酸配制新型焊剂的方法。