静止同步补偿器对降低多馈入直流换相失败的应用研究

发布时间：2018-04-14 19:02

本文选题：高压直流输电 + 多馈入直流输电系统　；参考：《山东大学》2015年硕士论文

【摘要】：随着我国经济的快速发展,多馈入直流输电系统格局将越来越多的出现在全国各地。换相失败是该系统中最常见也是比较严重的故障之一,可能会导致系统直流电流剧增、换流阀寿命缩短、直流输电功率减少及逆变侧弱交流系统电压不稳定等严重后果。若换相失败后的处理方式不当,可能引发后续的换相失败,连续换相失败可能引起换流站双极闭锁,导致直流传输功率中断。而对受端进行有力的无功支撑能够改善直流输电系统的运行性能,抑制多馈入系统中可能出现的连续换相失败现象。因此,本文对静止同步补偿器在多馈入系统中的应用进行研究,具有深远的理论意义和现实意义。本文首先对直流换相失败机理、判据、抑制及恢复措施等问题进行了理论研究,在总结国内外研究成果的基础上扩展到对多馈入直流换相失败连锁反应的现象及机理进行初步探索,分析多馈入特点对换相失败现象的影响。同时,对多馈入地区模型进行初步研究,在电磁暂态仿真软件PSCAD中建立仿真模型,对两端直流输电系统及双馈入直流输电系统中的典型换相失败故障进行了仿真模拟。其次,引出动态无功补偿装置对于缓解换相失败现象的理论分析,提出了直流系统的无功补偿原则。简单比较两种常用的动态无功补偿装置后,认为在解决换相失败问题时应选用静止同步补偿器STATCOM。接下来,研究了STATCOM的工作原理及应用,并从暂态稳定性、经济性及工程实用性等角度详细比较了各种S TATCOM主电路拓扑,最终选择适合应用于高压直流系统换相失败研究工况的链式△型主电路结构。接下来,本文分别对直流换流站控制系统及链式STATCOM的控制策略进行工程应用设计,并实现了STATCOM 与 HVDC系统的配合控制。计算直流输电系统的无功需求,实现了对STATCOM的需求分析及性能指标的计算,在PSCAD中建立含STATCOM的HVDC模型,并验证了上述配合控制策略的有效性。最终,在仿真软件PSCAD中对STATCOM并入双馈入系统进行建模仿真,从静态指标和仿真波形两方面验证了STATCOM对降低直流多馈入地区换相失败风险的作用,证明STATCOM加入系统后,能增强系统的换相失败免疫能力、降低换相失败故障发生概率,同时,对扩大交流系统的母线电压运行范围、故障后直流功率恢复有一定作用,能在一定程度上降低多馈入换相失败的风险。本文由实际工程需求出发,研究了动态无功补偿装置STATCOM在多馈入直流输电系统换相失败问题中的应用情况,通过电磁暂态仿真,证明STATCOM加入系统后能够起到一定的支撑作用,对于多馈入地区电网的安全稳定运行有较大意义,该研究具有较强的工程实用价值。
[Abstract]:With the rapid development of China's economy, the pattern of multi-infeed direct current transmission system will appear more and more throughout the country.Commutation failure is one of the most common and serious faults in the system, which may lead to a sharp increase in the DC current of the system, a shortening of the life of the converter valve, a decrease in DC transmission power, and the voltage instability of a weak AC system on the inverter side.If the treatment method after the commutation failure is improper, it may lead to subsequent commutation failure, and the continuous commutation failure may cause the bipolar locking of the converter station and lead to the interruption of DC transmission power.The reactive power support can improve the performance of HVDC transmission system and restrain the possible continuous commutation failure in multi-infeed system.Therefore, this paper studies the application of static synchronous compensator in multi-infeed system, which has profound theoretical and practical significance.In this paper, the mechanism of DC commutation failure, criterion, suppression and recovery measures are studied in theory.On the basis of summarizing the domestic and foreign research results, the phenomenon and mechanism of the multi-feed DC commutation failure chain reaction are preliminarily explored, and the influence of the multi-feed characteristics on the commutation failure phenomenon is analyzed.At the same time, the multi-infeed region model is studied, and the simulation model is established in the electromagnetic transient simulation software PSCAD, and the typical commutation failure faults in the two-terminal HVDC transmission system and the double-fed HVDC transmission system are simulated.Secondly, the theoretical analysis of dynamic reactive power compensation device to alleviate commutation failure is introduced, and the reactive power compensation principle of DC system is put forward.The static synchronous compensator STATCOM should be used to solve the problem of commutation failure after comparing two kinds of commonly used dynamic reactive power compensators.Then, the working principle and application of STATCOM are studied, and various S TATCOM main circuit topologies are compared in detail from the aspects of transient stability, economy and engineering practicability.Finally, the chained main circuit structure suitable for the study of commutation failure of HVDC system is selected.Then, the control strategy of DC converter station and chain STATCOM are designed, and the coordination control between STATCOM and HVDC system is realized.The reactive power requirement of HVDC transmission system is calculated, the demand analysis and performance index calculation of STATCOM are realized, the HVDC model with STATCOM is established in PSCAD, and the effectiveness of the above matching control strategy is verified.Finally, in the simulation software PSCAD, the modeling and simulation of the STATCOM incorporated into the double feed system is carried out, and the effect of STATCOM on reducing the risk of commutation failure in the DC multi-feed area is verified from the static index and the simulation waveform, and it is proved that after the STATCOM is added to the system,It can enhance the immunity of commutation failure and reduce the probability of commutation failure. At the same time, it can enlarge the voltage range of AC system and restore DC power after fault.It can reduce the risk of multi-feed commutation failure to some extent.In this paper, the application of dynamic reactive power compensation device (STATCOM) in the commutation failure problem of multi-feed DC transmission system is studied according to the actual engineering requirements. The electromagnetic transient simulation shows that STATCOM can play a supporting role in the system.It is of great significance for the safe and stable operation of multi-infeed power network, and the research is of great practical value in engineering.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM721.1

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