考虑电压和热稳定约束的可利用传输能力的快速算法

在现代电力市场环境,可利用传输能力(ATC)需要尽快提供给使用方。而在计算中要考虑的所有N-1故障因素导致了ATC计算任务非常繁重。基于此,提出了一种应用故障过滤与排序技术的ATC快速计算方法。首先,采用迭代线性潮流法(ILPF)对电网的N-1故障进行排序以筛选出热稳定极限和电压幅值约束条件下最严重的故障情况;然后,应用原始-对偶内点法对最严重故障情况进行ATC的计算,解决了ATC计算的耗时问题。算法的有效性通过IEEE30母线系统的仿真得到了验证。     

考虑电压和热稳定约束的可利用传输能力的快速算法

在现代电力市场环境,可利用传输能力(ATC)需要尽快提供给使用方.而在计算中要考虑的所有N-1故障因素导致了ATC计算任务非常繁重.基于此,提出了一种应用故障过滤与排序技术的ATC快速计算方法.首先,采用迭代线性潮流法(ILPF)对电网的N-1故障进行排序以筛选出热稳定极限和电压幅值约束条件下最严重的故障情况;然后,应用原始-对偶内点法对最严重故障情况进行ATC的计算,解决了ATC计算的耗时问题.算法的有效性通过IEEE30母线系统的仿真得到了验证.     

考虑电压稳定性约束的输电能力综合计算

在分析原-对偶内点法和连续性潮流方法计算系统输电能力各自优缺点的基础上．将两者结合,提出了一种系统输电能力的综合计算方法。该方法用原-对偶内点法优化得到的发电机出力值为连续性潮流方法提供最优的发电机出力方向。并用连续性潮流追踪系统从初始运行点到电压崩溃点的过程中各离散事件的变化过程,控制其向最优值靠近,从而提高系统的输电能力。对IEEE-14,30,118节点的算例做了测试,试验证明,该算法既能获得更大的输电能力,又能模拟系统实际运行状况,是常规的连续性潮流方法的完善。     

考虑暂态稳定约束的可用输电能力的计算

基于传统的最优潮流模型及多机电力系统的经典数学模型,利用隐式梯形积分法,将电力系统中所有发电机转子摇摆方程差分化为等式约束、发电机转子相对摇摆角稳定极限作为不等式约束,将其作为暂态稳定条件加入最优潮流的等式约束和不等式约束方程中,提出了一种考虑暂态稳定约束的可用输电能力计算的计算方法,用原始-对偶内点法求解该模型,并通过引入一个非线性互补函数改进原对偶内点法中的互补松弛变量在每次迭代中都必须保持正向的缺点,使优化问题的求解效率得到提高.14节点系统计算为例说明了该方法的有效性.     

考虑暂态稳定约束的可用输电能力的计算

基于传统的最优潮流模型及多机电力系统的经典数学模型,利用隐式梯形积分法,将电力系统中所有发电机转子摇摆方程差分化为等式约束、发电机转子相对摇摆角稳定极限作为不等式约束,将其作为暂态稳定条件加入最优潮流的等式约束和不等式约束方程中,提出了一种考虑暂态稳定约束的可用输电能力计算的计算方法,用原始-对偶内点法求解该模型,并通过引入一个非线性互补函数改进原对偶内点法中的互补松弛变量在每次迭代中都必须保持正向的缺点,使优化问题的求解效率得到提高。14节点系统计算为例说明了该方法的有效性。     

暂态稳定约束的可用输电能力计算

提出了一种基于暂态约束的最大可用传输容量的发电计划调整方法,利用单机等面积定则原理(SGEAC)对预想事故快速扫描、找出严重故障,并计算出临界机组的功率转移量的估计值,进而提出发电计划调整策略.该方法既具有时域仿真方法的精确性与良好的适应性,又能获得单机稳定裕度.与其他能量函数相比,该方法不必进行失稳模式的判别,避免了穷尽式搜索,能够适应多重故障、多摆失稳场景和不同的失稳模式.同时,该算法对所有严重故障集同时处理,满足了实时预防控制的要求.通过对不同失步模式的实例分析验证了所提方法的有效性.     

输电系统可用传输能力的研究

针对电力工业市场化改革的需求，综述了在电力市场环境下，输电网可用输电能力ATC（Available Transfer Capability)计算问题的研究现状及发展方向，介绍了ATC的定义，分析限影响ATC准确计算的各种不确定因素，针对ATC在线计算和离线计算的特点，提出了ATC计算的确定性模型和概率性模型，分析比较了目前ATC计算的几种算法的优,缺点，最后，展望了输电网可用输电能力计算中有价值的研究方向。     

含VSC-HVDC的交直流系统可用输电能力计算

利用等值电压源方法对电压源换流器进行等效,从而导出了适合于优化计算的电压源换流器型直流输电(VSC-HVDC)系统模型。该模型能够考虑换流器的各种控制方式及运行限制,且可用于多端直流系统。建立了含有VSC-HVDC的交直流系统可用输电能力计算模型,在模型中考虑了对换流器控制变量的多种优化方式,并应用序列二次规划法对模型进行求解。通过对修改后的EPRI-36节点交直流系统进行仿真计算,验证了所提出模型的实用性及算法的有效性。     

Assessment of available transfer capability of transmission systems

The available transfer capability (ATC) of a transmission system is a measure of unutilized capability of the system at a given time and depends on a number of factors such as the system generation dispatch, system load level, load distribution in the network, power transfers between areas, network topology, and the limits imposed on the transmission network due to thermal, voltage and stability considerations. This paper describes a method for determining the ATC between any two locations in a transmission system (single-area or multiarea) under a given set of system operating conditions. The method also provides ATCs for selected transmission paths between the two locations in the system and identifies the most limiting facilities in determining the network's ATC. In addition, the method can be used to compute multiple ATCs between more than one pair of locations. The proposed method is illustrated using the IEEE reliability test system (RTS)     

Available transfer capability and first order sensitivity

A method of calculating available transfer capability and the exploration of the first order effects of certain power system network variables are described. The Federal Energy Regulatory Commission has ordered that bulk electrical control areas must provide to market participants a “commercially viable” network transfer capability for the import, export and throughput of energy. A practical method for deriving this transfer capability utilizing both linear and nonlinear power flow analysis methods is developed that acknowledges both thermal and voltage system limitations. The available transfer capability is the incremental transfer capability derived by the method reduced by margins. A procedure for quantifying the first order effect of network uncertainties such as load forecast error and simultaneous transfers on the calculated transfer capability of a power system snapshot are explored. The quantification of these network uncertainties can provide information necessary for system operation, planning and energy market participation     

含VSC-HVDC的交直流系统可用输电能力计算

利用等值电压源方法对电压源换流器进行等效,从而导出了适合于优化计算的电压源换流器型直流输电(VSC-HVDC)系统模型.该模型能够考虑换流器的各种控制方式及运行限制,且可用于多端直流系统.建立了含有VSC-HVDC的交直流系统可用输电能力计算模型,在模型中考虑了对换流器控制变量的多种优化方式,并应用序列二次规划法对模型进行求解.通过对修改后的EPRI-36节点交直流系统进行仿真计算,验证了所提出模型的实用性及算法的有效性.     

新型快速混合式转换开关设计

在介绍混合式转换开关的工作原理及其动作过程的基础上,针对其中关键的换流电路进行了重点介绍,包括缓冲电路及吸收电路的结构原理设计,通过增加切入开关的方法解决换流回路导通瞬间电流过大的问题,达到保护目的。为解决系统关断时过电压问题,采用了2种设计方法:直接并联法与缓冲电路法,并通过理论分析给出了相关参数的计算方法,在样机中进行了实验验证。结果表明,混合式转换开关比传统机械式转换开关具有更加良好的特性,如快速导通、分断特性及限压特性等。同时,简单介绍了基于涡流斥力原理的超快速机械开关及涡流斥力计算的一种方法。     

Probabilistic approach to available transfer capability calculation

This paper suggests a probabilistic approach to calculate available transfer capability in the interconnected network. Calculation of available transfer capability is complicated because it involves determination of total transfer capability, transmission reliability margin and capacity benefit margin.In the suggested available transfer capability quantification method, total transfer capability is determined by the continuation power flow process. Transmission reliability margin and capacity benefit margin are evaluated by probabilistic load flow and Monte Carlo simulation, respectively.Proposed method is applied to a modified IEEE 72-bus 3-area system to calculate available transfer capability on two different time spans. Results of the case study show that suggested probabilistic approach can offer operational flexibility for system operators to consider system and market uncertainties.     

Assessment of oscillatory stability constrained available transfer capability

This paper utilizes a bifurcation approach to compute oscillatory stability constrained available transfer capability (ATC) in an electricity market having bilateral as well as multilateral transactions. Oscillatory instability in non-linear systems can be related to Hopf bifurcation. At the Hopf bifurcation, one pair of the critical eigenvalues of the system Jacobian reaches imaginary axis. A new optimization formulation, including Hopf bifurcation conditions, has been developed in this paper to obtain the dynamic ATC. An oscillatory stability based contingency screening index, which takes into account the impact of transactions on severity of contingency, has been utilized to identify critical contingencies to be considered in determining ATC. The proposed method has been applied for dynamic ATC determination on a 39-bus New England system and a practical 75-bus Indian system considering composite static load as well as dynamic load models.     

用随机规划法计算可用传输容量

该文提出了一种新颖的方法,来计算互联系统中通过预定界面的ATC(Availab1e Transfer Capability)值.它把电力系统中的不确定因素:发电机开断、线路开断和负荷预测误差,处理为随机变量,用基于随机规划法的混合方法,二阶段求索随机规划法和机会约束规划法求解.经过算例检验,此方法是有效的.     

Two-point estimate method for quantifying transfer capability uncertainty

A two-point estimate method is proposed in this paper to assess the power transfer capability uncertainty. This paper assumes that the uncertainty of the line parameters and bus injections involved in transfer capability calculations can be estimated or measured and shows how to estimate the corresponding uncertainty in the transfer capability. Instead of using a large number of simulations as required in the Monte Carlo approach, for a system with n uncertain parameters, the two-point estimate method uses 2n calculations of transfer capability to quantify the uncertainty. The proposed method uses a numerical method to calculate the moments of the transfer capability. The moments are then used in the probability distribution fitting. Using the obtained transfer capability uncertainty information and a desired level of reliability, an adequate transmission reliability margin can be determined for each transmission service. The proposed method can be used directly with a deterministic computer program and it does not require derivatives of the transfer capability. Test results of the proposed method are compared with those obtained from the Monte Carlo simulations and a truncated Taylor series expansion method.     

基于差分进化算法的动态可用输电能力计算研究

基于考虑暂态稳定约束的最优潮流(TSCOPF)建立了动态可用输电能力问题的数学模型.提出了采用差分进化算法(DE)求解考虑暂态稳定约束的可用输电能力(ATC)问题.利用不需要任何惩罚系数的合成适应度函数法处理约束问题.该算法原理简单,受控参数少,实施随机、并行、直接的全局搜索,易于理解和实现,且收敛性好,计算速度快,是一种求解非线性、不可微、多极值和高维的复杂函数的一种有效和鲁棒的方法.以WSCC9节点系统的计算结果为例验证了该方法的有效性和合理性.     

基于差分进化算法的动态可用输电能力计算研究

基于考虑暂态稳定约束的最优潮流（TSCOPF）建立了动态可用输电能力问题的数学模型。提出了采用差分进化算法（DE）求解考虑暂态稳定约束的可用输电能力（ATC）问题。利用不需要任何惩罚系数的合成适应度函数法处理约束问题。该算法原理简单,受控参数少,实施随机、并行、直接的全局搜索,易于理解和实现,且收敛性好,计算速度快,是一种求解非线性、不可微、多极值和高维的复杂函数的一种有效和鲁棒的方法。以WSCC9节点系统的计算结果为例验证了该方法的有效性和合理性。     

电力市场中最大输电能力的研究

在电力市场及转运出现后，输电能力作为技术指标为市场信号是一个越来越重要的参数。首先讨论最大输电能力（Total Transfer Capability,TC)的概念，并用图解方法分析了相关的制约因素，然后综述TTC的计算方法及研究现状，对基于直流潮流的电力传输分布因子法（PTDF），连续潮流法（CPF）和最优潮流法（OPF）等进行了述评，最后展望了TTC的求解思路和发展方向。     

Total transfer capability computation for multi-area power systems

This paper presents a method for multi-area power system total transfer capability (TTC) computation. This computation takes into account the limits on the line flows, bus voltage magnitude, generator reactive power, voltage stability, as well as the loss of line contingencies. The multi-area TTC problem is solved by using a network decomposition approach based on REI-type network equivalents. Each area uses REI equivalents of external areas to compute its TTC via the continuation power flow (CPF). The choice and updating procedure for the continuation parameter employed by the CPF is implemented in a distributed but coordinated manner. The proposed method leads to potential gains in the computational efficiency with limited data exchanges between areas. The developed procedure is successfully applied to the three-area IEEE 118-bus test system. Numerical comparisons between the integrated and the proposed multi-area solutions are presented for validation.