【作者】 周俊；

【导师】 郭剑波；

【作者基本信息】 华中科技大学 ， 电力系统及其自动化， 2012， 博士

【摘要】 随着特高压交直流输电工程的实施,交直流电网之间的相互影响变得日益复杂,电网运行特性不断变化,为保证规模巨大、结构复杂的交直流电网安全可靠运行,出于经济和技术层面考虑,必须采用有效的仿真手段对系统稳定特性、运行和控制技术进行全面深入的研究。与数字仿真软件相比,配备有与实际工程参数相一致的物理直流仿真装置可以更加准确的反映交直流相互影响特性,因此有必要采用电磁暂态全数字实时仿真与直流输电物理仿真相结合的方式,建立多回直流和特高压交流骨干网混合输电的数模混合仿真系统,对特高压电网的稳定特性进行试验研究。本文工作结合国家电网公司重大科技项目以及多个国家电网科技项目对数字物理混合仿真技术进行了相关的理论和试验研究,主要研究内容包括：(1)对大规模电力系统进行实时仿真时,并行计算效率是必须首先考虑的因素。本文分析了交直流大电网数模混合仿真系统的并行计算效率,确定了各因素对并行计算效率的影响,为实现大规模电网的实时仿真提供了依据和参考。要实现大规模电力系统的数字实时仿真,必须借助于大型计算机系统进行并行计算,同时必须综合考虑各个因素对并行计算效率的影响,以平衡系统性能,从而得到最优并行计算效率。(2)在广泛研究现有的数字物理混合仿真接口方法的基础上,结合实际数模混合仿真中各种不同的网络拓扑结构,分析了现有的输电线解耦方法存在的不足,提出了改进方法,系统解决了长线路,短线路,无线路情况下数字网络与物理仿真装置的接口问题；对于长度大于50km的输电线路可直接选择线路进行解耦,对于长度在50kn以下的线路通过补偿电容的方法转换成50km线路后也可实现数字侧与物理侧解耦,而对于无线路情况下,可选择支路部分电感,转换成1km线路再进行解耦。改进的接口方法使得数字物理网络分割可以在任意节点进行。(3)本文深入分析了数模混合实时仿真接口稳定性的形成机理,对接口延时、直流偏移、阻抗参数匹配、串并联谐振以及多端口相互影响对混合仿真接口稳定性的影响进行了深入分析。提出了改进的混合仿真接口方案,选择合适的软件和硬件实现了特高压直流输电系统与全数字仿真软件的数模混合实时仿真,全物理仿真与数模混合仿真结果的比较验证了改进的混合仿真接口具有较高的稳定性和仿真精度,解决了数模混合实时仿真的接口稳定性问题。(4)结合实际电网,对交直流大电网数模混合实时仿真系统进行了测试和试验研究。在世界上首次实现了多回高压/特高压直流输电系统的交直流大电网数模混合实时仿真,针对三华交直流混合输电系统中直流多馈入系统中交流系统故障对直流系统的影响,包括换相失败情况、系统恢复时间等一系列问题,采用本论文开发的数字物理混合仿真系统作了仿真分析,验证了离线仿真计算的结论,证明了本论文研究工作的实用性和必要性。本文研究成果初步实现了大规模电力系统数字物理混合实时仿真,将为我国联网电力系统的规划、运行提供有力的仿真分析工具。更多还原

【Abstract】 With the development of the UHVAC and UHVDC projects, interactions between ac and dc network are becoming more complex. To ensure the security and safety operation of such a large ac/dc hybrid power system, it’s necessary to study the system stability, operation and control issues in detail. For economic and technology concerns, a simulation tool has played important role. Compared with the digital simulator, the physical HVDC simulator with actual control and protection system can better reflect the interactions. Therefore, it’s necessary to combine the advantages of the electromagnetic transient full digital simulator with physical HVDC simulator, establish the multiple HVDC and UHVDC hybrid transmission system and study the stability issues of the UHV grid. This work is supported by key projects of the State Grid Corporation as well as several National grid projects of science and technology, the relevant theoretical and experimental research about power system digital and analog hybrid simulation technology are presented. The main contents are organized as follows:The parallel calculation efficiency is the paramount issue in large power system real time simulation. This paper analyzes the parallel efficiency of AC\DC grid analog digital hybrid simulation, determines the impact of various factors on the parallel computing efficiency and provides a basis and reference for real-time simulation. To achieve real-time digital simulation, super computer must be used. While factors that affect the simulation efficiency should be considered in order to get the most optimal calculation efficiency.On the basis of extensive research of existing interface method in accordance with the actual network topologies, the shortcomings of the existing transmission line decoupling method are analyzed, then the improved interfacing method under different conditions (long lines, short lines and none line) are given. If the length of the decoupling line is more than 50km, transmission line decoupling method can be used directly. If the length of the decoupling line is less than 50km, a capacitor compensation method is used to overcome the limit of the length of the decoupling line.If there is none lines, parts of the branch inductance is selected and converted to a lkm line. The improved interface method makes the digital and physical network decoupling can be carried out at any node.The closed-loop stability is the paramount issue in power hardware in-the-loop (HIL) simulation in regard to the operational safety and the experiment reliability. In this paper, a stability analysis of the power HIL simulation using TLM is first introduced with a simple example. Several factors (such as time delay, dc offset and resonance of the interface circuit) with respect to the interface stability are analyzed in detail. Then improvements are adopted to ensure interface stability. Through hybrid simulation and full physical simulation of the power hardware-in-the-loop (HIL) of a UH VDC link, it is revealed that the interface exhibit higher stability and accuracy than before under the given conditions.To more accurately study the interaction between ac and dc grid, PHIL simulation was used in a large power grid existing in China power system. PHIL simulation of a large power system with multiple HVDC\UHVDC lines has been achieved for the first time in the world. An interaction study is performed, including the commutation failures, the recovery characteristics after failure, etc. Comparisons of PHIL simulation against off line simulation proved the usefulness and necessity of this paper.The results of this study are the first realization of the digital and analog hybrid real-time simulation of large scale power network, this will provide strong technical support for planning and operation of interconnection power system in China.更多还原