【作者】 王峰；

【导师】 徐政；

【作者基本信息】 浙江大学 ， 电气工程， 2011， 博士

【摘要】 由于我国能源资源与需求呈逆向分布,客观上决定了我国要实行“西电东送、南北互供、全国联网”的电力资源优化配置,以实现能源的大范围转移,而直流输电技术在远距离、大容量输电方面的优势决定了其是最好的选择。虽然我国在直流输电技术方面起步较晚,但发展迅速,为了进一步提高直流工程的国产化水平,全面推动自主研发和科技创新,开发具有自主知识产权的高压直流输电基本设计软件包是其重要内容之一,本论文主要研究了高压直流输电基本设计中的几个关键问题,主要研究内容如下：(1)研究了换流变压器参数的确定方法。根据换流阀的浪涌电流水平,结合交流侧最大三相短路容量和直流系统的额定直流电压、电流等参数,应用数学解析公式计算最低要求的换流变压器短路阻抗,避免了工程上反复迭代的过程,并基于确定的短路阻抗值计算其他参数。以整流侧定电流逆变侧定电压控制方式为研究对象,考虑系统参数及相关的测量误差,研究了换流变压器分接头级数的计算。(2)论述了高压直流输电主回路稳态参数计算需要的基础参数,包括运行方式、约束条件和原始数据。接着讨论了与主回路稳态参数计算密切相关的换流变压器分接头控制,包括其功能、分类以及各自的优缺点。然后在考虑这些基础参数,并基于整流侧定电流逆变侧定电压,两侧换流变压器分接头角度控制方式,具体研究了主回路稳态参数计算的过程,并制定了详细的计算流程。(3)论述了无功设备的投切原则和高压直流输电无功管理需要考虑的因素。根据系统参数及无功设备容量,并基于主回路稳态参数计算结果和保持交直流系统间无功交换量在一定范围内的原则,详细研究了无功设备投切点的计算,并为确定和校验换流站无功设备投切顺序以及绘制无功投切曲线制定了详细的计算流程。(4)基于主回路稳态参数计算结果,研究了在考虑各种非理想条件下采用确定性算法计算三脉动谐波电压源,包括特征与非特征谐波。计算时采用时域分段算法,该算法根据各三脉动组中三个阀的状态,将三脉动电压波形在一个周波内分为六段。根据计算获得的分段区间将交流基频电压与各次谐波电压作用下的三脉动电压按此六个分段区间分别进行傅立叶分解,然后再将同次谐波合并获得最终三脉动源各次电压。(5)以计算高压直流输电工程的等效干扰电流衡量直流滤波器性能为目的,研究了在给定两侧三脉动谐波电压源条件下,线路采用全相耦合模型并结合网络分序模型计算沿线各次谐波电流的算法,包括直接流过直流极导线、接地极线路的谐波电流和感应到直流线路、接地极线路地线中的谐波电流。并基于直流侧谐波电流论述了等效干扰电流的计算过程。(6)研究了一种基于滤波器等效原则并且适用于工程实际的直流滤波器设计方法。通过将多调谐滤波器等效成对应个单调谐滤波器,以多调谐滤波器的主电容值和调谐次数为限制条件,先计算各个单调谐滤波器参数,再经过等效公式得到多调谐滤波器的参数。根据该方法,可以方便地通过调整等效单调谐滤波器的参数而改变多调谐滤波器的参数,同时能保持多调谐滤波器的主电容值和调谐次数的不变,提高了直流滤波器设计的效率。更多还原

【Abstract】 The fact that there is a reverse distribution between the energy resources and the demands determines our country has to implement the power optimal configuration, e.g. west-to-east power transmission, power exchange between south and north and nationwide interconnection. The advantages of HVDC in the field of long distance and large capacity transmission determine HVDC is the best choice. Although the HVDC technology starts relatively late in our country, it develops rapidly. In order to make further improvement in the localization of HVDC, and promote independent development and technological innovation comprehensively, developing HVDC design software package with independent intellectual property is an important content. This thesis makes researches on several important issues in basic design of HVDC and the main works are organized as follows:(1) According to the valve’s surge current level, in combination with three-phase AC maximal short-circuit capacity, rated DC voltage and DC current, the determination of minimal short-circuit impedance of the converter transformer is carried out through analytical formulas, avoiding the procedure of iteration in practical engineering. Based on the actual impedance, the other parameters of converter transformer are calculated. Considering the system’s parameters and measuring tolerances, tap range of converter transformer is calculated in detail.(2) The basic parameters for the calculation of main-circuit steady state’s parameters in HVDC transmission are discussed, including operation modes, constraint conditions and original data. Then the tap changer control of converter transformer which has close relation with steady state’s parameters is introduced, including its functions, categories, advantages and disadvantages. Based on the basic parameters and tap changer control, as well as the system’s control, the flow for calculation of main-circuit steady state’s parameters is established in detail.(3) The switch principle of reactive power equipments and the factors influencing the reactive power management for HVDC transmission are discussed. According to the system’s parameters, the capacity of reactive power equipments and the results of main-circuit steady state’s parameters, as well as the switch principle that keeping the exchange of reactive power between AC and DC system within a certain range, the calculation process for reactive power management is established in detail.(4) An algorithm for calculating the three-pulse harmonic voltages in the DC side is researched. In the algorithm, various asymmetries in firing angle, commutation reactance and transformer winding as well as the imbalance of ac voltage are considered. According to the states of valves, the waveform of the three-pulse voltage is divided into 6 segments in one cycle. In each segment, the voltage of the three-pulse model is calculated by considering the AC fundamental and harmonic voltages respectively. Then, through applying Fourier decomposition to the results of three-pulse voltage and merging the same orders of the harmonics, each harmonic order of the three-pulse voltage is obtained.(5) Based on the three-pulse model, an approach for calculating the DC side harmonic currents in HVDC systems is presented, including the harmonic currents flowing directly in the DC line and the grounding electrode line, as well as the harmonic currents induced in their screening wires. The DC transmission line is treated as a network element, and its coupled phase model is used to form the network nodal admittance matrix. The harmonic currents along the DC line are calculated in positive and zero sequence respectively, and then the whole harmonic currents along the DC line are synthesized by the two sequences. The calculation of equivalent disturbing current is also described.(6) For the purpose of designing DC filter more effectively, a DC filter design method which is based on the equivalent principle and is suitable for practical engineering is presented. By transforming multi-tuned filter to several single tuned filters, first the parameters of single tuned filters are calculated according to the restrictions of the multi-tuned filter’s main capacitor value and the tuned frequencies. Then transforming the single tuned filters back, the parameters of multi-tuned filter can be calculated. With this method the parameters of multi-tuned filter can be adjusted freely, meanwhile, the main capacitor value and the tuned frequencies can be kept unchanged.更多还原