【作者】 袁世强；

【导师】 房大中；

【作者基本信息】 天津大学 ， 电力系统及其自动化， 2009， 博士

【摘要】 我国电网“西电东送,南北互供,全国联网”的基本格局已经形成,各区域电网之间的电气连接和功率交换不断增强,电力系统低频振荡现象时有发生,而且在某些区域电网呈反复发生的趋势。国内外报道的低频振荡事故中,有不少是由大扰动激发后出现的。已有文献表明,用于抑制低频振荡的电力系统稳定器(PSS)装置在增强系统小扰动稳定性的同时,可能对系统暂态稳定性产生不利影响,甚至损害整体功角稳定性。本论文针对这种情况,从多机系统PSS参数协调设计问题入手,力图寻找一种平衡方案,使系统整体的功角稳定性得以提高。本论文取得的主要成果如下:本论文通过各种经典分析方法,证实了当PSS提供过强的阻尼转矩分量时,也会提供负的同步转矩分量,因此在增强系统小扰动稳定性的同时,可能会损害暂态稳定性。对现有采用模拟退火法协调设计多机PSS参数的方案提出改进,合理地处理了自变量取值约束。提出了一种新的目标函数,旨在保证系统特征值阻尼比和振荡频率位于某一预设范围;针对不同的研究系统,更容易合理地给出该目标函数中的预设门槛值。引入了另一种同样简单实用的模式搜索法来求解该优化问题。在十机新英格兰测试系统上验证了以上算法的效果和效率。进一步发展了用于多机系统PSS参数协调设计的轨迹灵敏度方法。通过轨迹灵敏度方法,获得系统动态性能指标相对于PSS待设计参数的梯度信息,给出更新PSS参数向量的搜索方向,能够找到使系统整体功角稳定性改善的PSS参数配置新方案。与原有实现相比,本论文在中间变量选取、公式推导、初值选择、取值范围约束处理、寻优区间排查、梯度向量信息利用等各方面作出改善。提出将基于最优控制变分法的轨迹逆积分技术用于求解上述的多机系统PSS参数协调设计问题。详细分析了上述两种方法的计算特点,找出了快捷高效的计算途径,对比了不同的计算方案,在四机双区域测试系统和十机新英格兰测试系统上取得满意的效果。尝试使用一种结构简单的附加逻辑控制器,消除PSS在遭受大扰动后可能对发电机的同步转矩分量产生的不利作用,在四机双区域测试系统和十机新英格兰测试系统上验证其效果。更多还原

【Abstract】 The fundamental framework of Chinese national power grid has now been settled as“power transfer from West to East, between North and South, with countrywide interconnection”. The electrical link and power interchange between regional power systems have thus been greatly improved, but still low-frequency oscillations happen from time to time, especially in certain areas. Quite a few of the low-frequency oscillations reported at home and abroad are due to large disturbances. Power system stabilizers (PSS) could be detrimental to the transient stability while boosting the small-signal stability, with the whole rotor angle stability spoiled. This dissertation tries to solve the above issue by coordinated design of PSS parameters in the multi-machine power system. There are possible balancing solutions where the overall angle stability is enhanced. The contents of this dissertation are as follows.Using several classical analysis approaches, it is confirmed in this dissertation that the excessive damping torque component offered by PSS is accompanied by its negative synchronizing torque component, which is the cause for the boosted small-signal stability and the impaired transient stability.The current simulated annealing method used for coordinated PSS parameter design is improved on the treatment of the bound constraints of arguments. A new objective function is proposed to ensure the damping ratio and oscillation frequency within a specified range. The merit is that it is easy to specify reasonable gate values for different power systems. Pattern search, another simple and practical method, is also adopted to solve the proposed optimization problem. The effectiveness and efficiency of these methods are proved on the 10-generator New England test power system.The trajectory sensitivity (TS) method used for coordinated PSS parameter design is further developed by this dissertation. The TS method is utilized to compute the gradient vector of the dynamic performance index of the power system with respect to PSS parameters to be tuned. Moreover, the search direction for updating the PSS parameters is given, and new PSS parameter configuration could be found for better overall angle stability. Compared to the original implementation, the dissertation modifies the selection of intermediate variables, formula derivation, the pick up of initial values, the sifting of searching interval, the arrangement of gradient information etc.A technique called“backward integration along trajectory”(BIAT) based on the calculus of variation in optimal control is proposed to solve the aforementioned problem of coordinated PSS parameter design. The features of both the TS and BIAT methods are compared in details. Promising effect is suggested by the case studies on the 4-machine 2-area test power system and the 10-machine New England test power system.An additional logic controller with simple structure is proposed to remove the possible unfavorable effect offered by PSS on the synchronizing torque component for the generator. The results are tested on the aforementioned test power systems.更多还原