The global project of AVC system based on hybrid control system and the theory of hybrid control are presented first.The paper analyzes the AVC system structure on the basis of its applaction in Zhongshan power system based on the integration SCADA/EMS platform.
为提高220 kV变压器预试的工作效率,减低劳动强度、停电时间和拆接引线遗留缺陷的风险,探索出220kV变压器不拆线进行预试的方法.经过拆线试验的数据对比和分析,证明220kV变压器不拆引线预试是可行的.
GIS是先进的电力设备,在运行中一旦发生故障,检修困难、时间长.因此需要对GIS设备的选型、监造、包装、运输、贮存、现场安装、验收、检修和运行维护等方面提出全过程管理的要求.通过一些实例,介绍GIS设备的全过程管理,供变电同行参考.
The correct actuation rate of the unbalance current protection for capacitor of AC filter is very low in HVDC system of SCG.It was found that most of the mis-operation of this protection occurs at the moment when inrush current of AC filter happened.Here the reason that inrush current happens at the moment when switching on AC filter is formulated theorectically at first,then with analyzing the practical operation examples,improvement suggestions are put forward to improve the reliability of HVDC system operation.
The structural particulars and working principle of zinc-oxide arrestor is formulated.With the defects found in the 500 kV E-BO circuit I phase A arrestor and that of Transformer #3 HV-side arrestor in 500 kV Dongguan substation as examples,the reason that caused these defects is analyzed.Counter-measure for detecting and preventing these defects in advance is put forward.
Through disassembly analysis of homemade GIS abnormal sound defects at the SF_6 Current transformer chamber,it is found out that the abnormal sound defect is caused by the assembly technical problems.Treatment methods and counter-measures are put forth.
Owing to the large scale and complicacy of mordern power grid,despatch mis-operation will arouse serious impact and loss in power grid and society as well.Here through analyzing the causes of various mis-operations,it shows that to enhance the technical quality and safety conscentiousness of the despatchers,improve the management system of despatch technical materials, are the fundamental works to prevent the happening of mis-operation.Basing on these,a workable anticipate control scheme to ensure power grid despatch safety is formed.
The method and process of surveying the coordination of Qiongzhou channel submarine power cable via side-scan sonar are introduced.With analyzing the benthic physiognomy images obtained,the submarine cable routes are measured and determined.
Analyzing the circumstance of over-crossing 500 kV transmission line of Yunguang±800 kV HVDC Transmision Line,and comparing with the normally used overcrosing construction method,a safe and suitable construction scheme is drawn for reference of similar crossing engineering.
Limited by the depth of both oil sump and that of the foundation,the pile raft cap is always designed rather thick, and the reinforcing bar is usually disposed in double way empirically.Here with finite element method the analysis to the conventional power transformer's pile raft foundation is made,basing on the tension compression member theory of the deep caps, improvement to the design of transformer foundation pile raft is proposed.Practice has proven that the improvement can ensure safety and reduce the construction cost of the pile caps.
Through analyzing the interior and exterior factors of toughed-glass insulator self-shattering,it is shown that pollution,high runnig voltage,high tension and breeze-vibration are the main factors that causes self-shattering of the toughed-glass insulator.To meet the needs of insulator replacement on a 500 kV power transmission line,a self-developed new tool for replacing the insulator closing the conductor in a combined insulator-string is introduced here for the reference of the similar maintenance work.
To solve the problems of power supply for Xunzhou Island,technical and economic analysis on three power supply schemes,local diesel power generation,marine-crossing of overhead line and marine-laying power cable is made.With comparing these schemes on construction scale,construction duration,the coordination with overall planning of the Chaozhou Harbor, engineering project design,construction,operation and maintenance afterward,taking into account the investment cost,environment protection and the increasing of power supply reliability,practice of two years' and half,has verified that the marine power cable is the best choice.
With an 110 kV unmaned substation as example,the calculation of substation DC power source batteries capacity and charger equipment calculation capacity configuration is introduced for the reference of substation colleaghes.
With an engineering practice as example,the various factors that affecting the HV transmission line construction cost are approached.Design optimizations,e.g.optimization of route,tower structures and foundations,the implementation of costlimiting are proposed to achieve engineering construction cost control under the maximum extend.
The vulnerability,out-of-day equipment and under-automation are the general problems of Jieyang distribution network in present,thus it can't meet the needs of social development in present.Opinions that should be taken into account when programming the distribution network are issued.In succeeding the plan,it is stressed that principle of planning first and implementation in steps.
With the reforming 220 kV overhead power line into under ground cable as an example,several schemes of cable metallic sheath grounding are analyzed and compared.The reasonable grounding scheme suited to the site conditions is optimized for the reference of the similar engineering.
With eigenvalue of state equation,the mechanism of low-frequency power swing is analyzed.Basing on phase compensation via vector-graphy analysis,an suppresion method is drawn.Parameters design process of PSS is discussed in detail. Using PSS-E simulation for two-generators system,the result has demonstrated intuitively the significance of PSS in suppressing low frequency power swing.Finally some suggestions are put forth for the further investigation on this topic.
To study the ecological effect of electro-magnetic field of HV AC transmission line,with analyzing the characteristics of its power frequency electro-magnetic field,the ecological effect and the improvement measures,model was built to calculate human induced current,human internal electric field intensity,human ion displacement amplitude.Results showed that when power frequency electric field intensity from HV AC transmission line was 4 kV/m,total induced current passing through human body is 60μA,human body internal electric field intensity is 0.176×10~(-3)V/m,and human body ion transferring amplitude is 8.01×10~(-12) m.
Obliquely inserted excavation pile foundation is a new-typed foundation for power transmission line tower developed in recent year.The joint between the cilindrical excavation pile and the oblique column with square cross-section is the key-point design of this structure.Here with the design of obliquely inserted excavation pile foundation in certain project as example, three-dimensional simulation analysis using finite-element software ANSYS is made.The stress disposition and displacement at cross-section changing /rigidity changing parts gained are in accordance with the theoretical analysis and reality.It can be the reference for the design and engineering practice afterward.
An B-phase instant earthing fault happened on the 500 kV Shanhua circuit No.2 of 500 kV Ling-xianshan substatoin. One of the two circuit breakers(C/B) of this circuit failed to reclose and tripped three phases C/Bs while another C/B reclosed normally.With analyzing series of relay protectoin actuations during the fault,and demonstrating relevant simultations,the reasons that causes such mis-operatoin is found.Corresponding counter measures are drawn..
