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Research On Electromagnetic Transient Key Problems And True Line Test Methods Of Half Wavelength AC Transmission Technology

Posted on:2019-08-15Degree:MasterType:Thesis
Country:ChinaCandidate:P GuFull Text:PDF
GTID:2382330545466689Subject:Power system and its automation
Abstract/Summary:PDF Full Text Request
The half wavelength AC transmission technology has the advantages of strong transmission capability,self balancing of the whole line reactive power,no installation of reactive power compensation equipment,good economic and reliability.In the near future,under the situation of building the global energy Internet,the semi-wavelength transmission technology,as an alternative to the UHVDC transmission technology,has received wide attention.In this paper,the multi conductor transmission line model of half wavelength transmission line is established by the electromagnetic transient simulation program of power system.Based on this,the problems of unbalance,potential supply current and overvoltage of UHV half wavelength line are studied and analyzed.Finally,the related research on half wavelength transmission engineering test is put forward.The main contents of the article are as follows:(1)this article uses the electromagnetic transient simulation program to establish the distribution parameter model of the line,and enumerates the layout scheme and transposition scheme of the multi group and half wavelength transmission lines.In the constructed point to the UHV half wavelength AC transmission system,the line imbalances and the system irregularities under different schemes are analyzed and studied.The distribution of voltage along steady state and steady state operation is considered,and a proposal is given considering its economy.(2)this article analyzes the potential supply current caused by the single phase grounding fault considering the transposition factor.The research shows that the half wavelength transmission line will produce a large potential supply current after the single phase grounding fault occurs.The maximum submersible current is obviously smaller after transposition,but it is still at a high level.The method of suppressing the submersible current by high-speed grounding switch is studied under the condition of line transposition,and the effect of line transposition point on the suppression effect of high speed grounding switch is analyzed.The conclusion is that the more close the line transposition point is to the high speed grounding switch,the better the effect of the high speed grounding switch restraining effect.(3)this article studies the steady running voltage of the half wavelength transmission line,the overvoltage of the power frequency load rejection,the overvoltage of the switching operation and the fault overvoltage,and analyses the time domain waveform of the related overvoltage electromagnetic transient process.For severe fault overvoltage,the suppression measures of "half wavelength line neutral point position forced grounding + arrester" are put forward.(4)this article takes into consideration the factors such as voltage grade,line length,network frame structure,operation condition and so on.From the Northwest 750 kV power grid,the line is picked out to be connected before and after,and a test scheme of the true type point pair half wavelength transmission system with a true type point to net structure of about 3000 kilometers is proposed.On the basis of this scheme,the steady-state and transient problems that need to be considered in the test process are analyzed and studied.The corresponding solutions for the more serious problems of the fault overvoltage and the potential supply current in the test process are put forward.
Keywords/Search Tags:Half wavelength AC transmission, Imbalances, Submersible current, Internal Overvoltage, Test for the true type transmission line
PDF Full Text Request
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