多馈入直流输电耦合作用研究
发布时间：2019-01-21 18:16
【摘要】：多馈入直流输电换相失败故障发生频繁,研究电网换相直流输电(Line-Commutated-Converter High Voltage Direct Current, LCC-HVDC)系统换相失败和多馈入直流输电耦合作用是解决多馈入直流输电换相失败故障的基础研究内容,有必要对其进行研究。 文章从换相失败的故障机理及影响因素两个方面对换相失败进行研究,以此为基础提出了基于触发角上限和快速提前触发的换相失败预防方法,该方法由基于触发角上限的换相失败预判方法和快速提前触发换相失败预防方法组成。基于触发角上限预判方法的核心理论依据为触发角上限的计算方法,该方法由换相电压时间面积这一概念推导得出。提出快速提前触发换相失败预防方法的目的是为了提供一种简单可靠、迅速的预防指令,用以快速的提前触发晶闸管,预防换相失败。在PSCAD/EMTDC环境下仿真的结果表明该方法可以有效降低由单相故障引起换相失败的概率。 为从稳定运行区间分析多馈入直流输电耦合作用,引入了视在短路比增量这一稳态指标,该指标将直流子系统间的相互影响等效为对受端交流系统短路比的增量。随后对视在短路比的计算方法进行研究,分析了直流电流、直流子系统容量、电气距离对视在短路比的影响,进而分析了系统运行特性随这些影响因素变化的趋势。进行了PSCAD仿真,仿真结果表明了将视在短路比增量用于分析双馈入直流输电系统的正确性和有效性。 为从电压稳定性角度分析多馈入直流输电耦合作用,提出无功潮流耦合作用分析方法,该方法通过无功潮流的变化分析了当某子系统受到无功扰动之后,各子系统电压变化的机理。为定量分析多馈入直流输电各子系统之间的无功潮流支撑作用,提出了无功潮流支撑系数这一稳态指标,并推导了该指标的表达式。基于无功潮流耦合作用分析方法,推导了双馈入系统中多馈入静态电压稳定性的表达式。该表达式揭示了无功潮流支撑系数、多馈入交互作用因子与静态电压稳定性之间的关系,结合表达式对无功潮流支撑系数的影响因素进行分析。最后,在PSCAD环境下的双馈入直流输电模型中进行仿真,验证理论推导的正确性。
[Abstract]:Commutation failure of multi-infeed DC transmission occurs frequently. The research of power grid commutation DC transmission (Line-Commutated-Converter High Voltage Direct Current,) LCC-HVDC) system commutation failure and multi-feed DC transmission coupling are the basic research contents to solve the commutation failure fault of multi-infeed HVDC transmission, so it is necessary to study them. In this paper, the commutation failure is studied from two aspects: the fault mechanism of commutation failure and the influencing factors. Based on this, a method of commutation failure prevention based on the upper limit of trigger angle and fast early trigger is proposed. This method is composed of two methods: commutation failure prediction method based on the upper limit of trigger angle and fast early trigger commutation failure prevention method. The calculation method of the upper limit of trigger angle is based on the core theory of the upper limit prediction method of trigger angle, which is derived from the concept of time area of commutation voltage. The purpose of this paper is to provide a simple, reliable and rapid preventive instruction to trigger the thyristor in advance and to prevent the commutation failure. The simulation results in PSCAD/EMTDC environment show that this method can effectively reduce the probability of commutation failure caused by single-phase fault. In order to analyze the coupling effect of multi-fed HVDC transmission from stable operation interval, a steady-state index, apparent short-circuit ratio increment, is introduced, which equates the interaction between DC subsystems to the increment of short-circuit ratio to the receiving AC system. The influence of DC current, DC subsystem capacity and electrical distance on the apparent short-circuit ratio is analyzed, and the variation trend of system operating characteristics with these influencing factors is analyzed. The PSCAD simulation results show that the apparent short-circuit ratio increment is correct and effective in the analysis of double-fed HVDC transmission systems. In order to analyze the coupling effect of multi-feed HVDC transmission from the angle of voltage stability, a reactive power flow coupling analysis method is proposed. The mechanism of voltage variation in each subsystem. In order to quantitatively analyze the support function of reactive power flow between subsystems of multi-fed HVDC transmission, the steady-state index of support coefficient of reactive power flow is proposed, and the expression of the index is derived. Based on the coupling analysis method of reactive power flow, the expression of multi-feed static voltage stability in double-feed system is derived. The expression reveals the relationship between reactive power flow support coefficient, multi-feed interaction factor and static voltage stability. Combined with the expression, the influence factors of reactive power flow support coefficient are analyzed. Finally, the simulation of double feed in DC transmission model under PSCAD environment is carried out to verify the correctness of the theoretical derivation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1
本文编号：2412902
[Abstract]:Commutation failure of multi-infeed DC transmission occurs frequently. The research of power grid commutation DC transmission (Line-Commutated-Converter High Voltage Direct Current,) LCC-HVDC) system commutation failure and multi-feed DC transmission coupling are the basic research contents to solve the commutation failure fault of multi-infeed HVDC transmission, so it is necessary to study them. In this paper, the commutation failure is studied from two aspects: the fault mechanism of commutation failure and the influencing factors. Based on this, a method of commutation failure prevention based on the upper limit of trigger angle and fast early trigger is proposed. This method is composed of two methods: commutation failure prediction method based on the upper limit of trigger angle and fast early trigger commutation failure prevention method. The calculation method of the upper limit of trigger angle is based on the core theory of the upper limit prediction method of trigger angle, which is derived from the concept of time area of commutation voltage. The purpose of this paper is to provide a simple, reliable and rapid preventive instruction to trigger the thyristor in advance and to prevent the commutation failure. The simulation results in PSCAD/EMTDC environment show that this method can effectively reduce the probability of commutation failure caused by single-phase fault. In order to analyze the coupling effect of multi-fed HVDC transmission from stable operation interval, a steady-state index, apparent short-circuit ratio increment, is introduced, which equates the interaction between DC subsystems to the increment of short-circuit ratio to the receiving AC system. The influence of DC current, DC subsystem capacity and electrical distance on the apparent short-circuit ratio is analyzed, and the variation trend of system operating characteristics with these influencing factors is analyzed. The PSCAD simulation results show that the apparent short-circuit ratio increment is correct and effective in the analysis of double-fed HVDC transmission systems. In order to analyze the coupling effect of multi-feed HVDC transmission from the angle of voltage stability, a reactive power flow coupling analysis method is proposed. The mechanism of voltage variation in each subsystem. In order to quantitatively analyze the support function of reactive power flow between subsystems of multi-fed HVDC transmission, the steady-state index of support coefficient of reactive power flow is proposed, and the expression of the index is derived. Based on the coupling analysis method of reactive power flow, the expression of multi-feed static voltage stability in double-feed system is derived. The expression reveals the relationship between reactive power flow support coefficient, multi-feed interaction factor and static voltage stability. Combined with the expression, the influence factors of reactive power flow support coefficient are analyzed. Finally, the simulation of double feed in DC transmission model under PSCAD environment is carried out to verify the correctness of the theoretical derivation.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM721.1
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1 陈修宇;多馈入直流系统电压相互作用及其影响[D];华北电力大学;2012年
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