The first localized back-to-back converter station started expansion

The first fully localized back-to-back DC intercon-nection project which connects Northwest and CentralChina power grids, 330-kV Lingbao Converter Stationhas now started construction for expansion.Lingbao back-to-back converter station situated inLingbao City of Henan Province is the first DC intercon-

Electromagnetic interference and shielding of valve hall in HVDC converter station

The electromagnetic interference(EMI)from the valve hall as an important consideration in the design of high voltage direct current(HVDC)converter stations is analyzed by electromagnetic field numerical method and measurements.By using moment method,the EMI filed strength level as well as radio interference level(RIL)of the valve hall during the normal operation are computed after an antenna model is built for the valve tower.According to the character of EMI obtained,the practical shielding measures for valve hall are discussed to satisfy the relative standards.The test results for the
500 kV converter station show that both the numerical method and shielding technique used in this paper are practical.

高压直流换流站中滤波电容器的振动与可听噪声(英文)

The filter capacitor stack is one of the main acoustic noise sources in high-voltage DC(HVDC) converter stations.As HVDC systems are built more and more recently,it is significant to research the audible noise of filter capacitors.In this paper,the current situation of research on vibration and audible noise of filter capacitors in HVDC converter stations,which is departed into three parts—generation mechanism,prediction methods,and reduction measures,is presented and the research achievements are discussed.Scholars have built the model that the alternating electric force caused by the voltage conduces to the vibration,which propagates to the enclosure and radiates audible noise.As a result,the parts contributing most to the generation of audible noise are the top and the bottom of capacitors. In the noise level prediction respect,several methods have been prospected including impact hammer,sweep frequency, impact current,monopole and Kirchhoff formula method,which are suitable for single capacitors or capacitors stacks individually.However,the sweep frequency method is restricted by experiment condition,and the impact current method needs further research and verified.On the other hand,CIGRE WG14.26 provides three sound reduction measures,but all of them are not so practicable,while MPP absorber and compressible space absorber prospected by Dr.Wu Peng are proved to be effective.The sound barriers are also considered by scholars,and the acoustic directivity performance of capacitors is also researched.Besides,the developing direction of each research field is prospected in corresponding part.

Complete Localization of HVDC Back-to-Back Project Realized

The first completely localized DC back-to-back project for asynchronous interconnection between Northwest and Central China plays an important role in realizing national power grid interconnection, spurring indigenous manufacturing industries and promoting DC transmission equipment. Insisting on the principle of autonomous innovation, this project was based on domestic forces in every aspect, from engineering organization, system design, equipment completion, engineering design, equipment manufacturing and procurement to construction and debugging. By passing through strict quality control, intermediate supervision and acceptance test and assessment, the project has been proved up to world advanced level.

An improved prediction method of subsequent commutation failure of an LCC-HVDC considering sequential control response

Subsequent commutation failure(SCF)can be easily generated during the first commutation failure(CF)recovery process in a line-commutated converter-based high voltage direct-current system.SCF poses a significant threat to the safe and stable operation of power systems,and accurate prediction of CF is thus important.However,SCF is affected by the operating characteristics of the main circuit and the coupling effects of sequential control response in the inverter station.These are difficult to predict accurately.In this paper,a new SCF prediction method considering the control response is proposed based on the physical principle of SCF.The time sequence and switching conditions of the controllers at different stages of the first CF recovery process are described,and the corresponding equations of commutation voltage affected by different controllers are derived.The calculation method of the SCF threshold voltage is proposed,and the prediction method is established.Simulations show that the proposed method can predict SCF accurately and provide useful tools to suppress SCF.

Economy Analysis of Flexible LCC-HVDC Systems with Controllable Capacitors

Commutation failure(CF)is a frequent dynamic event at inverter of LCC-HVDC systems caused by AC side faults which can lead to inverter blocking,interruption of active power transfer,and even system blackout.To eliminate CFs and improve system performance,new Flexible LCC-HVDC topologies have been proposed in previous research but with limited analysis on its economic performance.Therefore,to further validate the applicability of Flexible LCC-HVDC topologies,this paper utilizes Life-Cycle Cost Analysis model to analyze the life-cycle cost of inverter stations for conventional LCCHVDC,Capacitor Commutated Converter based HVDC(CCCHVDC)topology and Flexible LCC-HVDC topologies including Controllable Capacitor based Flexible LCC-HVDC,AC Filterless Controllable Capacitor based Flexible LCC-HVDC and improved Flexible LCC-HVDC.Through a case study based on a 500 kV,1000 MW LCC-HVDC scheme,comparison results show that the AC Filterless Controllable Capacitor based Flexible LCCHVDC topology and the improved Flexible LCC-HVDC topology have lower cost than the conventional LCC-HVDC and CCCHVDC topologies,which proves that the elimination of CFs can be achieved with reduced cost.

Experimental Analysis on Influence of Temperature and Bolted Torque to DC Contact Resistance of Terminal Connector in UHV Valve Hall

The overheating problems of terminal connectors severely threaten the operation of ultra-high voltage projects and cause enormous losses of economy,so a higher currentcarrying reliability of the connectors has an important engineering significance with the development of transmission capacity.In this paper,a bivariate mathematical model of contact resistance as functions of temperature and tightening torque was deduced based on the large current temperature rise tests.To perform such analysis,four typical terminal connectors,namely:overlapping terminal of aluminum plates,overlapping terminal of copper plates,overlapping terminal of plates with clad layer and overlapping terminal of copper rod with aluminum clamp,were chosen for the experiments.The changing rules of DC resistance with different tightening torques and different currents were studied.Then the empirical formula of contact resistance was deduced.Finally,temperature calculations of different terminal connectors were realized to verify the effectiveness of the bivariate mathematical model.