【作者】 莫育杰；

【导师】 何奔腾； 江道灼；

【作者基本信息】 浙江大学 ， 电气工程， 2013， 博士

【摘要】 随着电力电子器件电压等级和容量的不断增加,基于电力电子器件的固态限流器在电力系统中具有日益广泛的应用前景,而其中新型固态限流器以正常运行时对系统影响小、短路故障时无延时插入限流、无电压电流振荡冲击、以及桥路所承受电压等级较低等优点得到国内外研究的广泛关注。本文在对新型固态限流器已有的研究基础上,进一步对其关键技术做了深入研究,主要包括以下内容：提出了新型固态限流器中饱和型耦合变压器的设计方法。首先分析了饱和型耦合变压器的三种运行工况,并建立了在每一工况下的等效电路,在此基础上提出了饱和型耦合变压器的设计目标：在满足系统限流要求的前提下使正常运行时漏抗及故障限流时的副边电压尽量达到最小值。其次,论文针对此设计目标,得出了饱和型耦合变压器的详细设计步骤：1)确定变压器原副边变比及导线截面积；2)在空心电抗器设计的基础上,运用场路耦合的有限元法,得出满足限流要求的饱和型耦合变压器的一系列匝数与芯柱半径组合；3)进一步得出饱和型耦合变压器正常运行(副边等效短接)时的漏抗压降及故障限流(副边等效开路)时副边电压随心柱半径的变化规律,并通过曲线拟合寻优,得到最佳设计。最后通过一款应用于100V/1A系统的小样机试验与仿真结果进行对比,验证了以上设计方法的合理性。根据三相饱和变压器耦合固态限流器工作原理,建立了三相饱和变压器器等效磁路和限流器等效电路,并根据磁路和电路基本定律,结合铁芯分段线性磁化曲线,用解析法推导了三相饱和变压器耦合固态限流器工作过程。然后,在Ansoft/Maxwell软件及Anosft/Simplorer软件中分别建立了三相饱和变压器的三维有限元模型及限流器主电路模型,通过以上两款软件联合,采用场路耦合的三维有限元仿真,在对三相饱和变压器内部磁场分析的基础上,全面研究了限流器的工作过程,并重点对故障限流阶段三相饱和变原副边相电压间关系、原副边线电压间关系以及副边相电压及线电压间关系做了对比分析。最后为研究该限流器在多机系统中的限流效果,论文利用以上有限元仿真结果,获得了该限流器的非线性电感模型,并将该模型应用于3机12节点系统中进行了仿真研究。通过上述理论与仿真研究,得出该限流器的以下重要特性：正常运行时电压损耗很小,对系统影响可忽略,故障发生时可无延时自动插入限流,在故障限流阶段三相饱和变压器副边相电压及线电压远低于对应的原边相电压及线电压,且副边线电压峰值与相电压峰值之比远小于(?)3倍,这对于减小副边桥路的电压等级、直流电感及整套装置体积与成本具有重要意义。提出了适用于高压系统的自耦变压器耦合固态限流器的两类拓扑结构——双绕组自耦变压器耦合固态限流器以及三绕组自耦变压器耦合固态限流器,同时为了加速故障限流时桥路关断时间并减小直流电感,在以上拓扑结构中引入了带复合开关的全控桥路拓扑结构。之后论文采用解析法研究了以上两类限流器的工作原理,同时将全控桥路拓扑与常规桥路拓扑进行了对比研究,以证明全控桥路拓扑的优势所在。根据上述理论,设计了应用于220kV/1.5kA系统的双绕组及三绕组自耦变压器耦合固态限流器,采用了Matlab/Simulink软件分别仿真了双绕组和三绕组自耦变压器耦合固态限流器工作过程,并通过对比得出以上两款限流器的各自特点；为了进一步研究作为核心限流器件的自耦变压器,论文在Anosft/Maxwell中建立了其有限元模型,并与Ansoft/Simplorer中所建立的限流器主电路仿真模型联合,分析了应用于220kV/1.5kA系统的双绕组及三绕组自耦变压器在各个工作阶段的磁场分布特性,并在磁场分析的基础上,采用场路耦合的有限元法,得出了限流器的工作特性。最后通过小样机模型试验与仿真结果对比,验证了方案的合理性。为了解决FACTS装置在系统发生故障时的保护问题,研究了新型固态限流器在FACTS装置保护中的应用,提出了具有短路限流功能的FACTS装置的单相和三相拓扑结构,其中包括带饱和型串联变压器及故障旁路模块的拓扑结构。在建立装置在故障限流时副边等效电路的基础上,推导了故障时副边电感电流及电容电压的变化规律,并给出了其中关键参数的设计依据。然后以应用于1OkV/1kA系统的三相拓扑为例,通过仿真研究了其中限流器模块对FACTS装置的过压过流保护作用,其中包括对拓扑中串联变压器分别采用常规变压器和饱和变压器两种方案进行对比研究,以突出饱和变压器在故障保护中的优势；同时也对拓扑中引入故障旁路模块的方案进行了仿真,验证了该模块在抑制故障时FACTS装置中电容电压上升的重要作用。最后通过380V/3kVA限流式UPFC小样机试验,验证了方案的合理。更多还原

【Abstract】 With the increase of the voltage level and capacity of the power electronic devices, the solid state fault current limiters based on the power electronic devices have more and more extensive application prospect, of which the novel solid state fault current limiters (SSFCL) with the following advantages:negligible impact on the power system during the normal operating state, automatic response to limiting the fault current without time delay and without voltage and current oscillation and strike upon the fault inception, has been paid extensive attention in the field of the investigation of the fault current limiting technology both at home and abroad. Based on the achievements in the past, the key technologies of the SSFCL have been focused and studied in this paper, including:The design methodology of the saturated coupling transformer (SCT) in the novel SSFCL is proposed. Firstly, the three operating stages are analyzed, and the equivalent circuit is setup during each stage, based on which, the main objective of the design of the SCT is obtained, which is to reduce the leakage inductance during the normal operation stage(the secondary winding is equivalent to be short-circuited) and the secondary voltage of the SCT during the fault current limiting stage (the secondary winding is equivalent to be open-circuited)as soon as possible on the premise of the satisfying the requirement of the fault current limiting. Secondly, to achieve the design objective, the detailed design steps of the SCT are given:1) choose the turns ratio between the primary and secondary windings and the cross section of the wire of the SCT;2) based on the parameters obtained from the design of the air-core transformer, a series of the combinations of the parameters of the turns of the winding and the radius of the steel core of the SCT are obtained, by applying the field-circuit coupling FEA method;3) in addition, the change law of the leakage reactance voltage drop in the normal state and the secondary voltage of the SCT in the fault current limiting state with the core radius is achieved, and the optimal result is obtained by curve fitting and optimization. Lastly, the validity of the design methodology proposed is verified by the comparison between the results of the simulation and the experiment of the small-scaled prototype employed in the100V/1A system. Based on the operating principles of the three-phase saturated transformer coupling SSFCL, the equivalent magnetic and electrical circuits are obtained, and the working process of the SSFCL is analyzed applying the fundamental magnetic and electrical circuits principles combined with the subsection linear magnetization curve. Then the3-D FEA model of the three-phase saturated transformer and the topology model of the SSFCL are built up in the Anosft/Maxwell and the Ansoft/Simplorer software respectively. Applying the field-circuit coupling FEA method, and combining the two software packages above, the magnetic field inside the three-phase saturated transformer and the whole working process of the SSFCL is studied, during which, the emphasis is paid on the research of the relationships between the primary and secondary phase voltages, the primary and secondary line voltages, and the secondary phase and line voltages of three-phase saturated transformer during the fault current stage. Lastly, in order to research the fault current limiting effect of the SSFCL in the ulti-machine power system, employing the results of the FEA simulation achieved above, the nonlinear inductance model of the SSFCL is obtained, which is simulated in the3-machine12-node system. The analysis and simulation results show that the novel SSFCL has the following advantages:negligible impact on the power system during the normal operating stage, automatic response to the short-circuit fault, and during the fault current limiting stage the secondary phase and line voltages are far less than the values of the primary winding, further more, the ratio of peak values of the secondary line and phase voltage is far less than√3, which are of great significance to the reduction of the bridge voltage level, the DC reac, as well as the volume and cost of the whole equipment.Two topologies of the novel autotransformer coupling SSFCL employed in the high voltage level power system—two-winding and three-winding autotransformer coupling SSFCL(ATCSSFCL) are proposed, meanwhile, the fully controlled bridge topology with the combination switch is introduced to speed up the shutting off of the bridge and reduce the DC inductance. Then the operating principles of the two schemes of the ATCSSFCL are analyzed, in addition, both of the conventional and the novel bridge topologies are comparative studied, highlighting the advantages of the novel fully controlled bridge topology. According to the principles proposed above, the schemes of the two-winding and three-winding ATCSSFCL employed in the220kV/1.5kA system are designed, which are simulated in the environment of the Matlab/Simulink, and the respective characteristics of the two schemes are obtained by the comparative analysis of the simulation results. In order to research the autotransformer as the key fault current limiting device, its FEA model is set up in the environment of the Anosft/Maxwell, utilized to analyze the magnetic field distribution of the autotransformer employed in the220kV/1.5kA system during each operating stage combined with the circuit model built in the Ansoft/Simplorer software, based on which, the whole performance of the ATCSSFCL is obtained employing the field-circuit FEA method. Lastly, the feasibility of the proposed schemes are verified by the comparison between the results of simulation and experiment of the small-scaled prototype.To solve the problem of the protection for the FACTS equipments upon the short-circuit fault, the application of the SSFCL for the protection of the FACTS is studied, the single and three phase topology of the FACTS equipments with the fault current limiting function, including the topologies with the saturated transformer and the fault shunt module, are proposed. Based on the equivalent circuit of the secondary side during the fault current limiting, the change law of the DC inductance current and the voltage across the capacitor is obtained as well as the guidance for the key parameters of the scheme. Then the three-phase topology employed in the lOkV/1kA system is taken as the case study, the protection principle for the over voltage and over current is studied by simulation, including the comparative study between the schemes with the conventional and saturated transformer, which highlights the advantage of the saturated transformer in the fault protection, meanwhile, the scheme with the fault shunt module is also simulated to show its positive effect on suppressing the capacitor voltage rise. Lastly, the feasibility is verified by the380V/3kVA prototype experiment.更多还原