高压直流输电系统的仿真与交流侧故障时的换相失败特性研究

发布时间：2018-04-13 06:21

本文选题：交流非对称故障 + 直流控制系统　；参考：《华北电力大学(北京)》2017年硕士论文

【摘要】：随着直流输电技术的发展,直流系统的输送功率进一步提升。直流输电线路的增加也带来了更多换相失败的问题。因此能否正确的认识换相失败的问题,并能对其加以预测和判断成为一个亟待解决的问题。目前已经有很多专家学者对该问题展开了研究,现阶段研究发现,当交流系统发生非对称故障时,换流器的换相失败发生情况具有很强的随机性,不但取决于故障的类型,更与故障发生的时刻有关。此外通过对直流输电系统的仿真分析还发现,由于逆变侧相串联的换流器接入连接组别不同的换流变压器,导致换流器发生的换相失败的情况也有所不同。为了全面的分析直流的换相失败问题,对于本文的研究主要考虑了如下三个方面。首先,换相失败的问题受交流系统发生非对称的故障时刻影响,不同的故障时刻对发生换相失败的临界阻抗影响很大。本文利用换相面积的概念对此问题进行了详细的分析,并且在进行仿真分析时着重注意了故障发生时刻对换相失败造成的影响。其次,本文对换相失败的产生机理进行了详细的分析,并重点分析了换流器连接组别不同对换相失败问题的影响,并通过仿真与分析结合的方法对故障发生时刻影响同一故障点换相失败发生概率的问题进行了解释。此外结合换流阀在交流系统发生故障的实际触发过程对换相失败的判据进行了修改,基于该方法为分析解释造成换相失败的原因提供参考。最后,分析直流输电的控制系统,目前主流的直流输电控制系统可分为定熄弧角控制、定直流电压控制技术路线两种。两种控制系统均在我国直流输电工程中大量使用,工程实际经验表明两种控制系统均具有良好的控制响应特性,并能在换相失败后快速恢复。控制系统在交流系统发生故障时通常会采取提前触发的策略以避免换相失败的发生,本文将结合两种控制技术进行详细的介绍和分析。
[Abstract]:With the development of DC transmission technology, the transmission power of DC system is further improved.The increase in DC transmission lines also brings more commutation failures.Therefore, whether we can correctly understand the problem of commutation failure and be able to predict and judge it has become an urgent problem to be solved.At present, many experts and scholars have carried out research on this problem. At present, it is found that when asymmetric faults occur in AC system, commuter commutation failure has a strong randomness, which depends not only on the type of fault, but also on the type of commutator.More related to the time when the fault occurred.In addition, through the simulation analysis of HVDC transmission system, it is also found that the commutation failure of the converter is different due to the connection of inverter side phase converter connected to different converters of different transformer groups.In order to analyze the commutation failure of DC, the following three aspects are considered in this paper.Firstly, the commutative failure is affected by the asymmetric fault time of AC system, and the critical impedance of commutation failure is greatly affected by different fault time.In this paper, the concept of commutative area is used to analyze this problem in detail, and the influence of fault occurrence time on commutation failure is emphasized in the simulation analysis.Secondly, the mechanism of commutation failure is analyzed in detail, and the influence of commutator connection group on commutation failure is analyzed in detail.The probability of commutative failure at the same fault point is explained by the method of simulation and analysis.In addition, the criterion of commutation failure is modified in combination with the actual trigger process of commutation valve failure in AC system, which provides a reference for analyzing and explaining the causes of commutation failure.Finally, the control system of HVDC transmission is analyzed. At present, the mainstream HVDC control system can be divided into two kinds: constant arc angle control and constant DC voltage control technology.Both control systems are widely used in HVDC transmission projects in China. Practical engineering experience shows that the two control systems have good control response characteristics and can recover quickly after commutation failure.In order to avoid the commutation failure, the control system usually adopts the strategy of triggering in advance when the AC system fails. This paper will introduce and analyze the two control techniques in detail.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM721.1

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