【作者】 杨朋朋；

【导师】 韩学山；

【作者基本信息】 山东大学 ， 电力系统及其自动化， 2008， 博士

【摘要】 随着国民经济发展和企业的变革,电力系统规模和经营机制日益迅猛发展和变化,发电与用电的地域和时域差异、负荷峰谷差、不确定性及市场竞争的程度等都在加大,电力系统运行调度决策越来越复杂。在这一背景下,电力系统运行调度理论面临挑战、完善和适应,有针对性的对其深入研究具有重要的理论意义和实际价值。本文以数学优化理论为基础,以实际电力工业发展为背景,以机组启停、优化调度等电力系统运行调度理论的核心问题为线索,开展了细致而深入的研究与实践工作,该工作也是国家自然科学基金项目“电力系统运行调度中刚性优化与柔性决策理论研究”中的重要内容,本论文是这一研究、实践工作的总结。论文分为8章,第1章是绪论,第2章至第7章是在前人研究、实践基础上的主要工作,第8章是结论与展望。本论文的研究工作和创新性成果主要体现在如下方面:1.对机组组合与经济调度中拉格朗日乘子的差异及作用机理进行了研究与分析,在逆序排序的机组组合(Unit Decommitment)方法中提出一种新的拉格朗日乘子的修正方法,免去了繁复的经济调度计算,并对机组的搜索范围及机组运行的经济指标进行了相应的改进,在保证原有算法解的经济性的同时,使计算速度得到显著提高。2.机组投运风险水平与机组强迫停运容量呈离散型的分布关系,因而难以与机组组合的拉格朗日松弛法等有机结合。就这一问题,对系统投运风险曲线的两种拟合形式,即高斯函数和指数函数,进行了分析和研究,发现前者精度较后者明显提高。在此基础上,将投运风险度约束以解析表达的方式引入拉格朗日松弛法中,有机一体的完成了机组组合概率备用约束的优化处理,对大规模电力系统有良好的实用前景。3.将计及安全约束机组组合问题分解为两个子优化问题,建立了两个子优化问题间衔接与协调的约束表达,由此提出了两个子优化问题间交替求解的算法。两个子优化问题分别为无安全约束的机组组合问题和计及安全约束的优化潮流问题,通过在后者中引入虚拟变量来反映机组组合对电网输电元件安全的牵制及影响,并借用虚拟变量和发电转移因子,构建前者与后者间关联的补充约束条件,从而形成前者随后者变化的影响机制及优化方向的修正手段。算法充分兼容现有成型方法,符合电力系统实际,对解决安全约束对机组组合的制约,以及对机组组合方案评价,有良好的适应性。4.在对传统计及有功安全约束机组组合问题研究的基础上,进一步引入了电压无功约束,构建了较全面的机组组合优化模型,对该模型依据Benders分解原理,将其分解为主从两层及层间联系的表达,由此提出相应的主从决策迭代算法。其中,主决策是以直流潮流模型为基础的安全约束机组组合,从决策为给定有功模式下的系列无功优化,通过从决策引导的Benders割形成了主从关联的附加约束。在本文算法机制下,可充分兼容各种优秀的成型方法,形成了从无网络制约的机组组合,到仅考虑有功安全约束的机组组合,再到考虑电压无功制约的机组组合的灵活决策机制,符合大规模电网实际。5.针对考虑机组输出功率速率约束的安全经济调度问题,建立了Dantzig-Wolfe分解的主从优化问题及其迭代机制来求解。主问题是仅计及时间关联约束的优化问题,从问题是按研究期间所划分时段数构成的若干静态子优化问题。主问题在由从问题确定的解空间内寻优;从问题依据主问题解所对应的拉格朗日乘子来修正其目标,以间接松弛时间关联约束。在给出主从问题交替求解的收敛条件及其论证的基础上,提出了详细的计算方法和特殊问题的处理手段。此方法能有效解决带有时间关联约束的一类安全经济调度问题,具有对大规模系统实际应用的前景。6.在电力系统一定运行模式(有功、无功给定)下,通过潮流方程雅可比矩阵的特征结构规律分析,发现雅可比矩阵最小特征值对应的特征向量与无功分布有密切关系,进而可以作为电压支撑薄弱环节发现、二次电压控制及其中区域划分的依据,同时也可用以检验机组组合及机组有功功率分布是否合理。更多还原

【Abstract】 With the development of the national economy and the reform of enterprises, the scale and the operation mechanism of power systems are rapid developing every day. The degrees of areal and time difference between energy generation and consumption, the uncertainty and the difference between peak and valley load, the electricity market competition are all increasing which make the operation dispatch decision-makings ever more complicated. Against this background, the theory of power system operation and dispatch is facing challenge and must be improved to accommodate the situation. So it is of important theoretical and practical significance to make an in-depth study on the theory. The thesis, based on mathematical optimization theories and guided by power system operation and dispatch theory, performs meticulous and thorough work of research and practice. At the same time, the work summarized by the thesis is also the important content of the project entitled ’Rigid Optimization and Flexible Decision-making in Electrical Power System’ and supported by National Natural Science Foundation of China. There are 8 chapters in the thesis. The first chapter is the introduction. Chapter 2 to chapter 7 are the main works based on the accumulated research and practice. Chapter 8 is the conclusion and future works. The main works and innovative achievements of the thesis are as follows:1. On the basis of expounding the difference between Largrangian multipliers in ED and the ones in UC and their mechanisms of action, a new method of modifying Largrangian multipliers in unit decommitment (UD) method is proposed to reduce the burden of numerous economic dispatch computations. The proposed method not only reduces the search range but also improves economical indices of units correspondingly. Thus the accuracy and calculation speed of the original method are evidently enhanced.2. The relation between unit commitment risk and unit forced outage capacity is discrete, which leads to a difficult combination with the Lagrangian relaxation method of unit commitment. Two kinds of curve fitting of the unit commitment risk are analyzed. They are the Gauss function fitting and exponential function fitting. The research shows that the results of Gauss function fitting are more accurate than those of the exponential function fitting. By incorporating the analytic expressed unit commitment risk constraints into the Lagrangian relaxation method of unit commitment, the probability reserve constrained unit commitment problem can be truly achieved and optimized.3. The security-constrained unit commitment problem is decomposed into two subproblems. The constraint expression of connection and coordination between them is built, by which an alternative algorithm is proposed. The two subproblems are the unit commitment problem without security constraints and the optimal power flow problem considering security constraints. Virtual variables are introduced into the latter to reflect the restriction and influence of the unit commitment to transmission elements. Hence complementary constraint conditions correlating the two subproblems are set up by the use of the virtual variables and generation shift factors. They form the influence mechanism that the former subproblem varies according to the latter one and the means to modify the optimizing direction. The proposed algorithm is sufficiently compatible to the present method but also conforms to the reality of the power system. Thus it is quite adaptive to solve the security restraint phenomenon of the unit commitment and to evaluate the results of unit commitment problems.4. Based on the traditional research on the unit commitment considering active power security constraints, the voltage and reactive power constraints are further introduced to build a relatively comprehensive model. Using Benders decomposition, the optimization problem is decomposed into a master problem and a subproblem and the corresponding iterative process is also proposed. The master problem solves unit commitment considering security constraints based on the DC power flow model, the subproblem is composed of a series of reactive power optimization problems. Benders cuts guided by the subproblem form the additional constraints correlating the master problem and the subproblem. With the proposed optimization mechanism, all kinds of present methods are applicable, and a flexible decision-making mechanism, from unit commitment without network constraints to one with active power security constraints and finally to one with voltage and reactive power constraints is set up. It is applicable to the large scale power system in practice as well.5. For the security economic dispatch problems considering generator ramp rate limits, a master-slave optimization model and iterative solving mechanism based on Dantzig-Wolfe decomposition are proposed. In the master problem, only time correlation constraints are considered with the solution areas determined by slave problems. Depending on the study periods, the slave problems are made up of some static optimization sub-problems. In order to decouple the time correlation constraints indirectly, the slave problems objective functions are modified with the Lagrangian multipliers corresponding to the optimal solution of the master problem. Based on the convergence conditions and examples of the iterative solutions, the detailed algorithm and special problem solutions are proposed. The proposed method can solve the kind of security economic dispatch problems considering time correlation constraints effectively and also has the prospect of large scale application in practice.6. Under the condition that the operation pattern of the power system is given (active power and reactive power are given), analyzing Jacobian matrix eigenstructure variation mode of the power flow finds that the eigenvector determined by the minimum eigenvalue is closely related to reactive power distribution. This is the basis of searching weak links of voltage support, network partition in secondary voltage control and also can be used to test whether the unit commitment result and the active power distribution are reasonable.更多还原