Font Size: a A A

Study On Electromagnetic Transient Simulation Of AC/DC Power System With Multi-infeed HVDC Systems

Posted on:2010-07-15Degree:MasterType:Thesis
Country:ChinaCandidate:J L BaiFull Text:PDF
GTID:2232330392951662Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
High voltage direct current (HVDC) system has been widely used allover the world due to its advantages. It plays more and more important role inlong-distance power transmission and large-scale power systeminterconnection. In China, with the rapid development of economy and therapid growth of power loads, HVDC has been increasingly applied in thelong-distance power transmission and large-scale power systeminterconnection. By2020,27HVDC projects are expected to be in China,including six ultra high voltage direct current (UHVDC) projects. The PearlRiver Delta region and the Yangtze River Delta region will become two loadcenters with multi-infeed HVDC systems (MIHVDC) at that time.While HVDC brings huge economic benefits, voltage instability,transient instability, dynamic over-voltage and harmonic instability problemsmay happen at the same time due to AC-DC system interactions, especiallywhen HVDC connects to a weak AC system. When several HVDCtransmission systems feed into one AC system, the interaction between ACand DC systems becomes more complex, and leads to even more specialproblems. In addition, because switching of the thyristors in HVDC system,electromagnetic transient simulation is applied to analyze the dynamiccharacteristics of AC-DC system. This thesis studies the dynamiccharacteristics of MIHVDC system and the electromagnetic transientsimulation of large-scale AC-DC system with multi-infeed HVDC system.The main results obtained are as follows:1) Study multi-infeed short-circuit ratio and multi-infeed interactionfactor of multi-infeed HVDC system, and the relationship between them. Theory deduction indicates that the two definitions of multi-infeedshort-circuit ratio appear in current literatures are the same in nature, and thesimplified formula of multi-infeed interaction factor and the relationshipbetween it and the system impedance are derived. Furthermore, thecalculation of transient over-voltage caused by HVDC suddenly blocking inMIHVDC transmission system is given. The multi-infeed short-circuit ratio,multi-infeed interaction factors, and transient over-voltage of East Chinapower grid with HVDC are calculated, and some significant meaningfulconclusions are drawn.2) Propose the principle and method of the electromagnetic transientsimulation modeling of large-scale AC-DC system with MIHVDC system,and the validation method is also given. HVDC system in practice and itscontrol system are studied, based on which the electromagnetic transientsimulation models of the HVDC system and UHVDC system are established.3) The electromagnetic transient simulation model of East China PowerGrid in PSCAD/EMTDC environment is established. The calcaulaton ofpower flow and U/I characteristics of HVDC system, as well as failures, notonly show the validity of the simulation model, but also prove the principlesand methods proposed by this thesis. The characteristics of East China PowerGrid are studied, and some reasonable suggestions to improve are also given.At last, we point out that the converter bus voltage decreasing and distortionlead to commutation failure of several HVDC systems simultaneously inMIHVDC system. Further work on APF and SVC to improve convertercommutation performance can be done.
Keywords/Search Tags:HVDC, UHVDC, Multi-infeed HVDC System (MIHVDC), Multi-infeed Short-circuit Ratio, Multi-infeed Interaction Factor, Electromagnetic Transient Simulation, Simulation Model, PSCAD/EMTDC
PDF Full Text Request
Related items