电力系统在线主动解列控制算法

对在线主动解列策略的判定及控制框架进行简要介绍,提出电力系统在线主动解列算法:借助机组分群情况确定各个孤岛的主要电源,按照发电机和负荷的功率分配关系,研究负荷分群算法和设计解列断面搜索算法,实现负荷分群;考虑孤岛中功率调节特性,计算各个孤岛的不平衡功率情况,确定进一步切机、切负荷控制措施;在IEEE标准系统及实际电力系...     

电力系统功率分配的解析模型和算法

基于顺流分配矩阵提出一种有效快速的潮流跟踪解析模型及求解算法,并给出顺流分配矩阵、发电机出力矩阵和负荷矩阵等的构造方法及其相互间的关系,以此计算潮流跟踪分配系数矩阵,即可建立发电机对负荷分配的解析模型及求解算法.该模型直接解析表达了发电机出力与负荷功率间的解析关系,且可给出发电机对线路的功率分配关系.文中用定理证明了算法的正确性,保证了算法的可行性.该模型不需任何分摊原则,如：比例分摊原则等,而是通过矩阵分析直接得到解析模型.应用IEEE-14、IEEE-RTS系统及改变的IEEE-14环流系统证实了算法的有效性和正确性;同时,算例还证实了文中方法可用于无环流网络和环流网络,拓展了算法的应用范围.     

电力系统紧急情况下的动态分区和自主解列策略

在电力系统第三道防线的紧急控制中,当系统发生严重级联事故时,为保持系统稳定运行,自主解列控制是最后的有效手段。它的目标是保持各子分区的稳定性,并使整个系统在故障后的负荷总损失最小。本文讨论了电力系统紧急控制中的动态二分区和自主解列策略,首先结合发电机的慢同调分群算法,确定了系统的最优慢同调分群数,将振荡模式相近的发电机组等效为虚拟的发电机节点,然后在Laplace分区策略的基础上,提出新的加权指标,对Laplace分区策略进行改进,并提出启发式邻域搜索分区方法。最后将启发式就近削负荷方法应用于所有这些可能的割集,并计算各分区的负荷削减量,得到系统故障后总负荷损失最小的割集,即最佳解列控制策略。在IEEE118系统上的应用验证了改进的权重指标和所提出的混合分区策略的有效性。     

满足静态电压稳定增强要求的发电机最佳调整方法

为增强电力系统的静态电压稳定性,同时最大限度地减小运行人员的操作工作量,提出了一种综合经济性和静态电压稳定性的发电机最佳调整模型。该模型以发电机参与调整台数最少和发电成本最小为目标,约束条件包括系统负荷裕度满足设定提升要求和电力系统安全运行要求。该问题的数学本质是一个多目标非线性混合整数规划问题。为实现上述问题的求解,首先以线性灵敏度方法快速估算所需调整出力的发电机,求解控制数量最少的整数规划问题。然后以发电成本最小为目标,利用线性规划法求解各台发电机的调整出力值。最后在IEEE39节点算例和IEEE118节点算例进行仿真验证,结果表明所提模型与求解方法能很好地解决系统的静态电压稳定性增强控制问题。     

Enhanced state estimator incorporating adaptive underfrequency load shedding under contingencies via the alternating optimization method

An enhanced state estimator (SE) is proposed to incorporate the real-time underfrequency load shedding (UFLS) information in this paper. During contingencies, the historical SCADA measurements are not accurate enough while the PMU measurements may be inadequate for the SE. Considering that load shedding strategy is a common practice to prevent the system from collapse during contingencies, we can use the shedding information as a viable option to update/correct the SCADA measurements by employing proper techniques. The auxiliary binary variables and scheduled load shedding amount are introduced in the traditional weighted least square formulation so that a more accurate SE can be obtained. The alternating optimization method is utilized to solve the SE problem. Case studies are conducted on the IEEE 30- and 118-Bus system to illustrate the proposed methodology and demonstrate the evident improvements on the reconstructed states.     

孤网全黑状态的恢复网架和分区优化算法

电网故障后解列出的孤网是电力系统的重要组成部分,优先恢复系统中的孤立电网具有简化计算、加速电网恢复和及时带动重要负荷的优点。文中针对恢复的快速性和稳定性,综合考虑了孤网全黑状态的分区策略和各分区的恢复网架,引入最短启动时间算法和整数条件下的线性规划法,提出一种全新的孤网分区优化算法。该算法以机组、负荷最短启动时间为目标函数,以分区内的机组稳态有功、无功功率平衡为约束,将复杂的多目标非线性规划问题化简为单目标多约束的线性规划问题。文末以新英格兰10机39节点系统作为算例验证本文算法的有效性。     

能源互联网中基于多微网校正控制的安全约束最优潮流

近年来,能源互联网因其具有双向按需传输和智能分配能源的优点受到了高度重视。基于Benders分解的求解算法,提出了在能源互联网中通过多微网实现校正控制的安全约束最优潮流模型;在此基础上,提出了利用协调多个微网和系统机组解决故障后线路过载的激励控制策略。不同于直接负荷控制,该方法能够更好地促进主网与多微网之间的双向潮流以利于故障后电网的恢复。通过IEEE118节点标准系统验证了模型与算法的可行性与有效性。     

电力系统主动解列断面搜索方法与孤岛调整策略

主动解列是一种基于电力系统实时动态信息的紧急控制手段。及时而恰当的主动解列可以阻隔故障传播,避免保护连锁动作可能导致的系统崩溃,有利于大扰动后电力系统的快速恢复。在此背景下,提出一种包括快速搜索解列断面和优化调整孤岛的系统主动解列方案。首先,对在机器学习领域发展起来的谱聚类算法进行改进,提出含约束谱聚类算法,以计及发电机组的同调约束,从而将解列断面搜索问题转化为广义特征值求解问题。为克服在含约束谱聚类算法中采用传统k-medoids算法存在的对初始中心点敏感、搜索效率低的缺点,提出改进k-medoids算法并将其与约束谱聚类算法相结合,以求取最优解列断面。然后,对于解列后每个不满足安全约束的孤岛,优化调整其发电机组出力,必要时也可削减一些负荷,以维持每个孤岛的安全运行。最后,以IEEE 118节点系统和实际电网为例,说明所提方法的可行性和有效性。     

Real-Time Cascading Failures Prevention Through MAS Algorithm and Immune System Reinforcement Learning

The current options power engineers have during a pending CFs event have been limited to those that require load shedding. In this work, a novel algorithm is proposed that avoids loss incurrence as it does not use load shedding and involves real-time power redispatch from the generators through an appropriate combination. This method requires that the system possesses MAS capabilities to intelligently effect the power changes. A tool is needed to select the right combination for each system state as the use of lookup table and heuristics would be ineffective for large systems. The innovative use of AIS, as a reinforcement learning tool and not an optimization tool, is proposed for selecting the appropriate combination. The results obtained when lookup table, heuristics, and AIS are used to select the combination for a real-time experimental system are compared. The test system is the generation and transmission side of IEEE 30-bus system; and the CFs prevention algorithm is activated once the system is in an N-1 contingency state. IEEE 118-Bus System was also used to test the efficacy of AIS-MAS algorithm on large systems. The AIS-MAS algorithm proposed showed great promise for preventing CFs.     

Representation of a grid-tied microgrid as a reduced order entity for distribution system dynamics and stability studies

Microgrids comprising multiple distributed resources are being increasingly considered for integration into electricity networks. Considering the multiplicity of the distributed resources in a single location and distributed nature of such single entities, it is impractical to represent them as detailed models in power system simulations. Hence, it will be attractive for electricity utilities to employ simplified models of microgrids in dynamic studies. This paper proposes a method for representing grid-tied microgrids as simplified generator or load units in such studies. For this purpose, the paper takes an approach in investigating the applicability of modal analysis as a tool for model equivalencing of grid-tied microgrids with inverter and non-inverter interfaced distributed generators. Validity of the reduced order dynamic equivalents is tested under different operating conditions: power export and import modes, with different load types and fault conditions. Scalability of the model equivalencing approach is demonstrated using a case study developed based on the IEEE 13-Bus test feeder. Furthermore, the model equivalencing is applied on microgrids in a multi-microgrid environment to validate the methodology. The dynamic model equivalent of the microgrid can be represented as a current source at the point of common coupling while retaining all imperative dynamic characteristics. The proposed methodology is also applicable to distribution network clusters comprising distributed generators.     

考虑暂态稳定的风电穿透功率极限计算模型

为保证风电并网系统的稳定性,建立考虑暂态稳定的模糊随机机会约束规划模型计算风电穿透功率极限。针对风电出力和负荷的不确定性,模型中将两者作为模糊随机变量处理;模型中考虑暂态稳定约束时,根据发电机有功出力和转角的关系,通过时域仿真分析将系统的暂态稳定约束转化为发电机的出力限制约束。采用数学优化方法和时域仿真法相结合来求解所提模型。最后通过在IEEE14节点上仿真分析,证明了暂态稳定约束是风电穿透功率极限的关键约束条件之一。     

空调聚合商参与下的负荷控制与配电网重构

空调负荷的激增降低了配电网运行安全裕度,空调负荷聚合商已成为参与分散式温控负荷控制的新兴商业模式。文中提出面向聚合商参与的配电网温控负荷控制与运行重构策略模型,通过运行方式调整和负荷响应调节,耦合作用于系统安全运行。其中,不同聚合商以空调负荷调节协议方式集中管理温控负荷资源,并以分段报价方式争取市场利益;配电公司以最小化结算成本为目标,统筹多时段运行重构和负荷控制决策。通过凸规划方法进行约束条件等效,利用Mosek求解处理后混合整数二阶锥规划模型,确保了策略的计算效率。采用改进的IEEE 33节点系统算例验证了所提方法的适用性与有效性。     

基于信息间隙决策理论的气?电耦合配网滚动调度方法

面向气?电耦合配网，提出一种基于信息间隙决策理论（information gap decision theory，IGDT）的多能协同优化调度方法。首先，采用二阶锥优化(second-order conic program, SOCP)松弛描述配电网与天然气管网的能量流特征，利用电/气/冷/热多能互补及协同转化作为运行灵活性提升的重要手段，以经济性最优为原则，建立气?电耦合配网调度的确定性优化模型。在此基础上，提出基于IGDT的多能协同滚动调度方法，生成时变的动态风险边界。最后，在基于IEEE 33节点配电网和比利时20节点天然气网络的多能耦合系统中对所提方法进行了测试验证。算例结果表明，所提调度方法可以充分发挥气?电耦合配网的多能互补优势，并克服了传统滚动调度方法对于可再生能源预测精度的依赖，有效提升了系统对不确定性风险的承受能力，进而在鲁棒性与运行经济性之间取得合理权衡。     

考虑最少线路切换数量的电压稳定性增强优化方法

为提升电力系统的电压稳定性,提出一种基于输电线路切换的电压稳定性增强控制模型,该模型以最少的切换输电线路数量为目标来满足电力系统负荷裕度的提升需求。为灵活构建线路切换数学模型,提出基于支路追加法将线路切换融入原问题模型中。为降低模型求解难度,提出一种阶段式求解策略：基于负荷裕度对线路参数的灵敏度快速预筛选出可以提高系统负荷裕度的候选切换集,降低0-1整数变量的搜索范围;基于外逼近和松弛策略将原问题分解为2个子问题进行迭代求解,进一步提高模型的求解速度和精度。IEEE 118节点和IEEE 662节点系统仿真结果验证了所提模型与方法的有效性。     

Two approaches to transient stability-constrained optimal power flow

Formulation of transient stability-constrained optimal power flow (TSC-OPF) and finding a practical solution for the problem have gained much attention recently. In this paper, two approaches to include transient stability constraints in the OPF problem considering detailed dynamic models for generators and their controls are introduced. The first method is based on the maximum relative rotor angle deviation (MRRAD) of generators which suits systems that have specific requirements on MRRAD. The second method represents the transient stability margin of the system based on generators output power (GOP) and hence does not rely on MRRADs. The transient stability boundary can be represented by a nonlinear function of GOP. The Artificial Neural Network (ANN) curve-fitting tool is used to derive a mathematical formulation for the transient stability boundary (TSB). The closed form representation of the TSB is then inserted in the OPF problem as a new constraint. The proposed method is examined using the WSCC 9-bus, the New England 39-bus and the IEEE 300-bus test systems. The results indicate that the proposed methods lead to lower computational time in solving TSC-OPF which has been a serious challenge for this problem.     

Improved multilevel bipartitioning for controlled power system islanding

Nowadays interconnected power systems work close to their limits because of increased economic benefits. If a severe disturbance occurs in any part of the interconnected power system, it can be propagated through it. If no intelligent supervisory action is taken, a power system may be driven into an emergency state which could either cause system collapse by natural islanding or total system blackout. One possible measure to be put in effect in an emergency state is controlled power system islanding. In this paper, our previously proposed multilevel approach for controlled islanding is improved by using slow coherency grouping of generators in the aggregation phase. The approach has been applied to the IEEE 118 bus power system. The results indicate that the best partitioning of the power system is obtained with minimum generation/load imbalance in the islands, and with the coherent groups of generators maintained in each island making the restoration easy. A comparison of the computational complexities involved in the spectral, multilevel kernel k‐means and the improved multilevel approaches is made by applying these methods to the IEEE 9 bus, the IEEE 30 bus, the IEEE 39 bus, the IEEE 57 bus, the IEEE 118 bus, the IEEE 300 bus, the 2383 bus Polish and the 2746 bus Polish power systems to show the suitability of the proposed approach for controlled islanding of large‐scale power systems. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

计及冷负荷效应时变特性的含风储联合系统负荷恢复策略

随着风电大规模接入电力系统,风电与储能结合构成的风储联合系统成为提高风电消纳能力的重要措施之一。在电力系统恢复阶段,如何构建合理的风储联合系统调度策略以加快系统恢复速度成为当前的研究热点。为此,提出了一种计及冷负荷效应时变特性的含风储联合系统负荷恢复策略。介绍了输电系统恢复后期的负荷恢复优化方案;提出了考虑冷负荷效应时变特性和风储联合系统运行约束的输电系统负荷恢复模型,将冷负荷效应描述为关于停电时间的函数,并在风储联合系统的运行约束中考虑了储能系统的寿命约束。为了提高模型的求解效率,提出了基于Benders分解的求解框架,所构建的主问题模型和子问题模型均为混合整数线性规划模型,可调用商业求解器进行高效求解。以IEEE 39节点系统为算例验证了所提模型和方法的有效性。     

全局输配电网电压稳定故障筛选与排序的分布式计算方法

随着传统配电网向含大量分布式电源的主动配电网转变,输电网、配电网电压稳定评估已不再适宜各自独立计算。基于输电网、配电网分属于不同控制中心调控,提出一种全局输配电网电压稳定故障筛选与排序的分布式计算方法。该方法分为两阶段：阶段1中采用输配电网主从分裂分布式潮流工具在系统要求最小负荷裕度值的工况下进行各预想故障的潮流计算,采用最优乘子法筛选出潮流不可解的严重故障;阶段2中采用基于输配电网分布式连续潮流的步长加速二次曲线拟合方法计算严重故障的负荷裕度并进行排序。由1个IEEE 118节点输电网和2个IEEE 33节点配电网组成的全局输配系统的仿真算例表明所提方法能够快速可靠地实现全局输配电网电压稳定故障筛选与排序。     

考虑光-荷不确定性和旋转备用约束的主动配电网经济优化调度策略

分布式光伏、储能装置等大量分布式电源接入主动配电网(active distribution networks,ADN)后,光伏出力、负荷和旋转备用容量的多重不确定性对主动配电网经济调度的可靠性提出新的挑战。考虑了光伏出力及负荷不确定性,对旋转备用容量进行概率约束,以调度过程中运行成本最小为目标函数提出了一种主动配电网经济优化调度模型。通过所提出的潮流约束线性化方法和离散步长变换方法,将机会约束规划(chance constrained programming,CCP)模型转化为易于求解的确定性混合整数线性规划(mixed-integer linear programming,MILP)模型,并通过CPLEX求解器进行求解。基于IEEE-33节点配电网系统对所提方法进行验证。算例结果表明,所提策略的系统计算时间显著减少,优化效果更好,且可以通过适当设置旋转备用容量概率约束的置信水平实现主动配电网可靠性与经济性间平衡。     

考虑光-荷不确定性和旋转备用约束的主动配电网经济优化调度策略

分布式光伏、储能装置等大量分布式电源接入主动配电网(active distribution networks,ADN)后,光伏出力、负荷和旋转备用容量的多重不确定性对主动配电网经济调度的可靠性提出新的挑战。考虑了光伏出力及负荷不确定性,对旋转备用容量进行概率约束,以调度过程中运行成本最小为目标函数提出了一种主动配电网经济优化调度模型。通过所提出的潮流约束线性化方法和离散步长变换方法,将机会约束规划(chance constrained programming,CCP)模型转化为易于求解的确定性混合整数线性规划(mixed-integer linear programming,MILP)模型,并通过CPLEX求解器进行求解。基于IEEE-33节点配电网系统对所提方法进行验证。算例结果表明,所提策略的系统计算时间显著减少,优化效果更好,且可以通过适当设置旋转备用容量概率约束的置信水平实现主动配电网可靠性与经济性间平衡。