用分块矩阵法求解LP问题

给出了求LP问题最优解的分块矩阵解法,此方法避免了单纯形法多次画表的麻烦。     

基于不同算法求解子问题的Benders分解法在无功规划中的应用

利用Benders分解法将复杂的非线性无功规划问题分为投资子问题和运行子问题,通过约束割集将子问题联系在一起,在2个子问题间迭代求解,经过有限次迭代,最终求出最优解.求解子问题时,运用Dantzig-Wolfe分解法求解运行子问题,运用改进单纯形法求解投资子问题,并考虑了多种运行方式下最优的无功优化方案.     

电力系统微机保护中开平方浮点算法的改进

在分析开平方迭代算法收敛速度的基础上,提出了浮点数开平方的初值选取改进算法。该算法具有算法简单、迭代次数少、精度高等特点,较好地解决了开平方运算时间较长的问题。     

采用分布式单纯形法的微电网分散式动态经济调度

对含多种分布式电源的微电网,基于分布式单纯形法,提出了一种求解微电网动态经济调度问题的分散式优化算法。通过对目标函数进行线性化,建立了微电网动态经济调度的线性规划模型。将每个分布式电源均视为独立的智能体,从而将线性规划模型中的成本向量和约束方程系数矩阵按智能体进行分块,进而采用分布式单纯形法求解。每次迭代过程中,智能体通过通信网络传递当前解对应的最优基和成本向量。所提算法不需要中央控制器的参与,智能体间具有一定的信息保密性,且通信次数与通信网络的直径成线性增长的关系。最后,以某实际微电网为测试系统,验证了线性化模型的准确性和算法的有效性。     

利用带上、下界变量的线性规划法求解有功安全校正问题

安全约束最优化问题及其实际应用,近年来已作了大量的研究。采用线性规划法(LP)求解这一问题,可以避免采用某些非线性规划算法时所出现的收敛性困难,并具具有足够的精度。如果随后再进行一次常规A.C.潮流解,就能得到更高的精度。本文利用带上、下界的修正单纯形法,求解安全约束最优化问题之一的有功安全校正问题。并对IEEE30节点试验系统,做了一些数值试验。由于解算时间十分快速,因此具有应用于在线目的的潜力。     

交流采样中开平方算法的研究

在分析开平方迭代算法收敛速度的基础上,提出了开平方的初值选取改进算法。本算法具有算法简单,迭代次数少,精度高等特点,较好地解决了开方运算时间长问题。同时分析了求有效值（幅值）的开平方运算时间误差,并作改进。     

基于仿射变换的内点算法及其在可靠性评估中的应用

提出基于仿射变换的内点算法求解大规模电力系统可靠性评估。首先,给出了基于仿射变换的内点算法原理和计算步骤,用Fortran语言编写了求解最小切负荷子程序,在使用时需要把电力系统切负荷模型化为标准形式。为验证该算法的有效性,采用IEEE-RTS系统为例,用蒙特卡洛(Monte-Carlo)法模拟系统状态,用直流潮流进行状态评估,对于超负荷故障状态进行有功优化调整。采用基于仿射变换的内点算法求解最小切负荷量。计算结果表明,采用基于仿射变换的内点算法求解最小切负荷量过程中,最大迭代次数为16次,最小迭代次数为3次。该方法不仅适用于求解大规模电力系统的有功调整优化,也适于其他大型线性规划问题。系统规模越大,迭代次数的优势越明显。     

一种新算法在经济负荷分配中的应用

为求解复杂的不连续、非凸、非线性电力系统的经济负荷分配问题,提出了一种单纯形法(NM)和粒子群算法(PSO)相结合的NM-PSO算法.该算法将单纯形算子嵌入到PSO算法中,把适应值最好的一部分粒子用单纯形法来更新,其余粒子用PSO算法寻优,从而提高PSO算法后期的寻优能力.NM-PSO充分利用PSO算法强大的全局搜索能力和NM快速确定性的局部搜索能力,提高了NM-PSO算法的寻优能力和收敛速度,该算法应用于经济负荷分配问题得到的优化结果好于其他方法.     

基于ACO-PSO算法的变电站巡检机器人路径规划研究

针对机器人路径规划的传统ACO(蚁群)算法存在迭代次数多、收敛速度慢、容易陷入局部最优和出现死锁状态等问题,提出一种改进的ACO算法。结合PSO(粒子群优化)算法对传统ACO算法进行改进,减少迭代次数,提高收敛速度;通过增加随机性来扩大搜索范围,避免局部最优;利用蚂蚁回退策略解决死锁状态问题。仿真实验结果表明:改进ACO算法可以快速准确地搜索到最优路径,具有很好的寻优与避障能力。     

基于改进CORDIC算法的DDS设计

针对基本CORDIC算法的DDS计算速度随迭代次数增加而降低的问题,对CORDIC算法提出了一些改进.采用了角度分解预测旋转方向和多级迭代并行计算的方法,代替传统算法的多重迭代.时序仿真结果表明:改进的算法实现相位幅度转换;与基本CORDIC算法相比,在保持数据较高精度的同时提高了运算速度.此种设计具有运算速度快、计算...     

A tutorial description of an interior point method and itsapplications to security-constrained economic dispatch

The authors deal with the use of successive linear programming (SLP) for the solution of the security-constrained economic dispatch (SCED) problem. They tutorially describe an interior point method (IPM) for the solution of linear programming (LP) problems, discussing important implementation issues that really make this method far superior to the simplex method. A study of the convergence of the SLP technique and a practical criterion to avoid oscillatory behavior in the iteration process are also proposed. A comparison of the proposed method with an efficient simplex code (MINOS) is carried out by solving SCED problems on two standard IEEE systems. The results show that the interior point technique is reliable, accurate, and more than two times as fast as the simplex algorithm     

Finding all solutions of piecewise‐linear resistive circuits using the dual simplex method

An efficient algorithm is proposed for finding all solutions of piecewise‐linear (PWL) resistive circuits using linear programming (LP). This algorithm is based on a simple test (termed the LP test) for non‐existence of a solution to a system of PWL equations in a given region. In the conventional LP test, the system of PWL equations is transformed into an LP problem, to which the simplex method is applied. However, this algorithm requires a very large number of pivotings because the simplex method is applied on many regions. In this paper, we introduce the dual simplex method to the LP test, which makes the average number of pivotings per region much smaller (less than one, for example) and makes the algorithm very efficient. By numerical examples, it is shown that the proposed algorithm could find all solutions of large‐scale problems, including those where the number of variables is 300 and the number of linear regions is 10³⁰⁰, in practical computation time. Copyright © 2002 John Wiley & Sons, Ltd.     

An improved stator flux estimation in steady-state operation fordirect torque control of induction machines

This paper presents an improved stator flux estimation technique based on a voltage model with some form of low-pass (LP) filtering. In voltage-model-based stator flux estimation, an LP filter is normally used instead of a pure integrator to avoid integration drift problem due to DC offset, noise, or measurement error present in the back electromotive force. In steady-state condition, the LP filter estimator will degrade the performance and efficiency of the direct torque control (DTC) drive system since it introduced magnitude and phase errors, thus resulting in an incorrect voltage vector selection. The stator flux steady-state error between the LP filter and a pure integrator estimator technique is derived and its effect on the steady-state DTC drive performance is analyzed. A simple method is proposed to compensate for this error which results in a significant improvement in the steady-state drive performance. Simulation based on this technique is given and it is verified by experimental results     

改进卡尔曼滤波在北斗伪距定位中的研究

针对最小二乘迭代法定位精度不高和卡尔曼滤波迭代收敛次数较多并对初始位置过于敏感的缺点,采用最小二乘迭代法和改进的卡尔曼滤波相结合的模型方法,该算法先用最小二乘迭代法对初始位置进行定位,再用改进的卡尔曼法进行滤波,仿真结果表明,该算法与最小二乘迭代法、卡尔曼滤波法、最小二乘和卡尔曼滤波结合等现有算法相比,其迭代5次达到收敛,迭代次数最少,且定位精度提高了60%。该算法可在北斗伪距定位上进行应用,可用于导航定位、也可用于网络RTK初始位置的定位。     

基于响应表面法的电缆终端结构和材料参数优化

在对电缆终端的尺寸参数和材料特性进行优化时,若目标函数和约束条件不存在显示函数关系,需采用随机类优化算法进行多次有限元求解,从而产生优化过程迭代次数多、计算效率低的问题。文章使用响应表面法(RSM)先构建出较精确的响应表面模型,以显示的函数表达式描述出目标函数和约束条件与设计变量的关系,然后采用优化算法对含有非线性约束的优化问题进行求解。这样的优化过程大大减少了有限元计算次数,提高了计算效率。     

An efficient algorithm for finding all DC solutions of piecewise‐linear circuits

An efficient algorithm is proposed for finding all DC solutions of transistor circuits where characteristics of transistors are represented by piecewise‐linear (PWL) convex monotone functions. This algorithm is based on a simple test (termed the linear programming, LP, test) for non‐existence of a solution to a system of PWL equations in a given region. In the conventional LP test, the system of PWL equations is transformed into an LP problem by surrounding component PWL functions by rectangles. Then the dual simplex method is applied, by which the number of pivotings per region becomes very small. In this letter, we propose a new LP test using the dual simplex method and triangles. The proposed test is not only efficient but also more powerful than the conventional test using the simplex method or rectangles. Copyright © 2008 John Wiley & Sons, Ltd.     

Combined heat and power (CHP) economic dispatch solved using Lagrangian relaxation with surrogate subgradient multiplier updates

This paper presents a flexible algorithm to solve the combined heat and power (CHP) economic dispatch problem. The CHP economic dispatch is solved in two levels known as the lower level and higher level. The higher level is the optimization of the surrogate dual function for the relaxed global constraints in which the surrogate subgradient is used to update the Lagrangian multipliers. Coherently, the lower levels are the optimization of the subproblems taking in count each of its local constraints. Flexibility for the choice of algorithm is given at the lower levels optimization techniques with the condition that the algorithm is able to improve its search at each iteration. It is also seen that simple step size rules such as the ‘square summable but not summable’ and ‘constant step size’ could be used easily and leads the method to convergence. In addition this paper illustrates the ear clipping method used to modify the common nonconvex feasible region of CHP benchmark problems to a convex region which subsequently enhances the search for an optimal solution. The algorithm is then justified through a numerical test on three benchmark CHP problem with a nonconvex feasible region. Results prove that the algorithm is reliable and could be easily implemented even on a much complex and nonconvex problems.     

Periodic steady state analysis using shooting and wave-form-newton

This paper describes a method of determining the forced periodic steady state response of non-linear circuits. the method is closely related to the work of Aprille and Trick Proc. IEEE, 60 , 108-114 (1972) and also to the finite difference method for solving a boundary value problem. The new approach is a shooting method in the sense that in every iteration an initial value problem is solved. It is, however, also a relaxation method, because in every iteration a periodic wave-form is obtained. This is achieved by solving in each step a linear time-dependent differential equation whose solution can be easily transformed into a periodic solution satisfying this linear equation. Because the iteration takes place on wave-forms rather than initial values and every solution satisfies the boundary conditions, the method is robust. It will be shown that for a causal approximation of the time derivatives the iterated wave-forms are equal to those found using the finite difference methods.     

含VSC-HVDC交直流系统精确化离散最优潮流的研究

原对偶内点法在求解含电压源换流器的高压输电(Voltage source converter based high voltage direct current,VSC-HVDC)的交直流系统最优潮流(Optimal power flow,OPF)问题时,有较高的效率与准确性,但是无法很好地解决含离散变量的OPF(如无功优化),而智能算法在解决此类问题时易于陷入局部最优解,同时计算时间过长。因此提出一种含离散惩罚函数的混合内点法算法。算法的主要思想是以内点法为框架,对连续变量进行优化,在当对偶间隙小于一定值时,对离散量的计算中引入罚函数,同时随着迭代量差值的变化随时调整罚函数的罚因子的大小。通过算例表明,该算法稳定性高,寻优能力强,能够很好地解决含VSC-HVDC交直流系统的离散变量的优化问题。     

A homogeneous linear programming algorithm for the securityconstrained economic dispatch problem

This paper presents a study of the simplified homogeneous and self-dual (SHSD) linear programming (LP) interior point algorithm applied to the security constrained economic dispatch (SCED) problem. Unlike other interior point SCED applications that consider only the N security problem, this paper considers both (N-1) and (N-2) network security conditions. An important feature of the optimizing interior point LP algorithm is that it can detect infeasibility of the SCED problem reliably. This feature is particularly important in SCED applications since line overloading following a contingency often results in an infeasible schedule. The proposed method is demonstrated on the IEEE 24 bus test system and a practical 175 bus network. A comparison is carried out with the predictor-corrector interior point algorithm for the SCED problem presented previously (see ibid., vol. 12, no.2, p.803-10, 1997)