【作者】 王鹏；

【导师】 邱晓燕；

【作者基本信息】 四川大学 ， 电力系统及其自动化， 2003， 硕士

【摘要】 随着HVDC输电系统在电力系统中投入越来越多，交直流并联系统和多馈入HVDC系统正在逐渐增多。在这种情况下，交流系统和直流系统，不同的HVDC系统间都将存在相互作用。为了确保这种相互作用对整个电网的电压稳定性没有不利的影响，用系统化的方法来分析这些系统就显得尤为重要。最近，一种基于特征值分解技术的模态分析方法，已用于交直流混合系统的电压稳定性分析中。在此方法中，不仅用最小特征值来估计系统电压稳定性，而且它们的相关特征向量也包含着重要的信息，如系统中干扰对整个系统的影响大小等。 本论文进一步研究了这些模态信息在电压稳定性分析中的使用。用一种简单的方法可以求得降阶雅可比矩阵，由于降阶雅可比矩阵的元素都是交直流混合系统中一些参数的代数函数，如有效短路比、功率基准比、连接阻抗和系统潮流等，因此，矩阵的特征值也与这些参数相关。对于交直流并联系统，采用电力系统分析综合程序(PSASP)验证了负荷改变时最小特征值的变化情况。对于多馈入HVDC系统，在最小特征值为零的情况下，可以根据这种关系作出有效短路比—连接阻抗图，即电压稳定图。利用电压稳定图即可确定整个系统的电压稳定边界，从而确定整个系统的电压稳定运行区域和不稳定运行区域。这样就可以比较简便地判断出一个具体的运行状态是否是电压稳定的。在求最小特征值的同时，求出该最小特征值对应的左、右特征向量，利用左、右特征向量来计算在最小特征值为零时的换流母线参与因子。参与因子最大的母线就是临界母线，即电压稳定性最差的母线。该母线也是采取补偿措施来提高电压隐定性的最有效位置，根据电压稳定图和最小特征值图可以评估补偿措施的效果。本文还讨论了一些系统参数对电压稳定性的影响，包括换流器控制模式和四川大学硕士学位论文(2003)功率基值比。当换流器控制模式从定功率控制变为定电流控制时，总是改善系统的电压稳定性。更多还原

【Abstract】 With the increased use of HVDC transmission systems in power systems, situations have arisen and will be even more frequent in the future, where sigle-infeed HVDC system with a parallel AC line and several HVDC systems are located in close of each other. It is evident that interactions between the different HVDC systems will occur in such configurations, and it is of importance to analyze such systems in a systematic way to ensure that there are no risks of adverse interactions. A method based on the eigenvalue decomposition technique, known as modal analysis of multi-infeed HVDC systems. In this method, not only the critical eigenvalues are useful in evaluating the voltage stability of the system, but their associated eigenvectors also contain information on the most severe disturbances to the system.In this paper, the use of these modal information for such analysis id further exploited. The elements of the Reduced-Jacobian Matrix are functions of some parameters of the system. For example, Effective Short Ratio , Power Base Ratio , Coupling Impedance and Load Flow of the system. For single-infeed HVDC system with a parallel AC line, Computer simulations using Power System Analysis Software Package (PSASP) were performed. For multi-infeed HVDC systems, when the minimum eigenvalue of the system becomes zero, the voltage stability graph can be plotted Effective Short Circuit Ratio as function of coupling impedance. Using the voltage stability graph, the voltage stability margin can be known. The bus participation factors can be computed from the left and right eigenvectors associatedwith the minimum eigenvalues. The AC commutation bus with the largest participation factors is the critical bus, meaning that it has the largest involvement in the voltage instability. Consequently, it is also the most effective system location for implementing remedial measures.The significant influence of system parameters on the voltage stability are also investigated. A change in converter control mode from constant-power to constant-current always improve system voltage stability.更多还原