A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansi...A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.展开更多
Optimal power flow(OPF) has been used for energy dispatching in active distribution networks.To satisfy constraints fully and achieve strict operational bounds under the uncertainties from loads and sources, this pape...Optimal power flow(OPF) has been used for energy dispatching in active distribution networks.To satisfy constraints fully and achieve strict operational bounds under the uncertainties from loads and sources, this paper derives an interval optimal power flow(I-OPF)method employing affine arithmetic and interval Taylor expansion.An enhanced I-OPF method based on successive linear approximation and second-order cone programming is developed to improve solution accuracy.The proposed methods are benchmarked against Monte Carlo simulation(MCS) and stochastic OPF.Tests on a modified IEEE 33-bus system and a real 113-bus distribution network validate the effectiveness and applicability of the proposed methods.展开更多
随着新能源发电技术与直流输电技术在大电网中的广泛应用,需要提出含新能源的交直流混联电网静态电压稳定分析方法。为此,该文针对含常规直流输电和多端柔性直流输电的交直流混联电网,采用区间数描述新能源电站出力的不确定波动,建立了...随着新能源发电技术与直流输电技术在大电网中的广泛应用,需要提出含新能源的交直流混联电网静态电压稳定分析方法。为此,该文针对含常规直流输电和多端柔性直流输电的交直流混联电网,采用区间数描述新能源电站出力的不确定波动,建立了交直流混联电网静态电压稳定裕度(static voltage stability margin,SVSM)区间计算的2个双层最优潮流模型,即计算SVSM区间上界的min-min模型和计算SVSM区间下界的max-min模型。计算区间SVSM上界的min-min双层优化模型可直接合并为单层优化模型求解。计算SVSM区间下界的max-min模型需要先通过二阶锥松弛和凸包络松弛等方法将内层模型转化为凸规划模型,并通过对偶优化理论得到内层凸规划模型的对偶规划模型,进而转化为单层优化模型求解。通过对修改后的IEEE-39节点系统和南方电网2个交直流混联电网算例的计算分析,并与蒙特卡洛抽样法和拉丁超立方抽样法的计算结果比较,验证了所提出方法的正确性与高效性。展开更多
The active power loop flow(APLF)may be caused by impropriate network configuration,impropriate parameter settings,and/or stochastic bus powers.The power flow controllers,e.g.,the unified power flow controller(UPFC),ma...The active power loop flow(APLF)may be caused by impropriate network configuration,impropriate parameter settings,and/or stochastic bus powers.The power flow controllers,e.g.,the unified power flow controller(UPFC),may be the reason and the solution to the loop flows.In this paper,the critical existence condition of the APLF is newly integrated into the simultaneous power flow model for the system and UPFC.Compared with the existing method of alternatively solving the simultaneous power flow and sensitivity-based approaching to the critical existing condition,the integrated power flow needs less iterations and calculation time.Besides,with wind power fluctuation,the interval power flow(IPF)is introduced into the integrated power flow,and solved with the affine Krawcyzk iteration to make sure that the range of active power setting of the UPFC not yielding the APLF.Compared with Monte Carlo simulation,the IPF has the similar accuracy but less time.展开更多
为描述新能源发电等电力系统运行参数的不确定性对系统的影响,掌握系统的区间潮流分布,提出一种适于求解含新能源的交直流混联电力系统区间最优潮流(interval optimal power flow,IOPF)。源于区间优化法,将系统的新能源发电出力、节点...为描述新能源发电等电力系统运行参数的不确定性对系统的影响,掌握系统的区间潮流分布,提出一种适于求解含新能源的交直流混联电力系统区间最优潮流(interval optimal power flow,IOPF)。源于区间优化法,将系统的新能源发电出力、节点负荷功率等不确定量表达为区间变量,引入到交直流混合系统最优潮流计算的非线性规划模型中,建立了区间最优潮流计算的非线性区间优化模型。根据区间匹配和区间极值取值等原理,将该区间规划转化为两个确定性的非线性优化问题,并采用现代内点算法求解,得到了区间最优潮流待求变量的边界信息。IEEE 14、118和300节点标准系统的计算结果表明,与蒙特卡罗模拟结果对比,所提出方法具有较高的求解精度,对IOPF目标函数区间半径和区间均值的计算误差不超过9%和0.8%,且易于实现、计算效率高,具有广泛的应用前景。展开更多
基金supported by International Cooperation and Exchange of the National Natural Science Foundation of China(Grant No.52061635104).
文摘A large number of load power and power output of distributed generation in an active distribution network(ADN)are uncertain,which causes the classical affine power flow method to encounter problems of interval expansion and low efficiency when applied to an AND.This then leads to errors of interval power flow data sources in the cyber physical system(CPS)of an ADN.In order to improve the accuracy of interval power flow data in the CPS of an ADN,an affine power flow method of an ADN for restraining interval expansion is proposed.Aiming at the expansion of interval results caused by the approximation error of non-affine operations in an affine power flow method,the approximation method of the new noise source coefficient is improved,and it is proved that the improved method is superior to the classical method in restraining interval expansion.To overcome the decrease of computational efficiency caused by new noise sources,a novel merging method of new noise sources in an iterative process is designed.Simulation tests are conducted on an IEEE 33-bus,PG&E 69-bus and an actual 1180-bus system,which proves the validity of the proposed affine power flow method and its advantages in terms of computational efficiency and restraining interval expansion.
基金supported by Fundamental Research Funds for the Central Universities (No.2016XS02)National Natural Science Foundation of China (No.61772167)
文摘Optimal power flow(OPF) has been used for energy dispatching in active distribution networks.To satisfy constraints fully and achieve strict operational bounds under the uncertainties from loads and sources, this paper derives an interval optimal power flow(I-OPF)method employing affine arithmetic and interval Taylor expansion.An enhanced I-OPF method based on successive linear approximation and second-order cone programming is developed to improve solution accuracy.The proposed methods are benchmarked against Monte Carlo simulation(MCS) and stochastic OPF.Tests on a modified IEEE 33-bus system and a real 113-bus distribution network validate the effectiveness and applicability of the proposed methods.
文摘随着新能源发电技术与直流输电技术在大电网中的广泛应用,需要提出含新能源的交直流混联电网静态电压稳定分析方法。为此,该文针对含常规直流输电和多端柔性直流输电的交直流混联电网,采用区间数描述新能源电站出力的不确定波动,建立了交直流混联电网静态电压稳定裕度(static voltage stability margin,SVSM)区间计算的2个双层最优潮流模型,即计算SVSM区间上界的min-min模型和计算SVSM区间下界的max-min模型。计算区间SVSM上界的min-min双层优化模型可直接合并为单层优化模型求解。计算SVSM区间下界的max-min模型需要先通过二阶锥松弛和凸包络松弛等方法将内层模型转化为凸规划模型,并通过对偶优化理论得到内层凸规划模型的对偶规划模型,进而转化为单层优化模型求解。通过对修改后的IEEE-39节点系统和南方电网2个交直流混联电网算例的计算分析,并与蒙特卡洛抽样法和拉丁超立方抽样法的计算结果比较,验证了所提出方法的正确性与高效性。
基金the National Natural Science Foundation of China(Grant No.51877061).
文摘The active power loop flow(APLF)may be caused by impropriate network configuration,impropriate parameter settings,and/or stochastic bus powers.The power flow controllers,e.g.,the unified power flow controller(UPFC),may be the reason and the solution to the loop flows.In this paper,the critical existence condition of the APLF is newly integrated into the simultaneous power flow model for the system and UPFC.Compared with the existing method of alternatively solving the simultaneous power flow and sensitivity-based approaching to the critical existing condition,the integrated power flow needs less iterations and calculation time.Besides,with wind power fluctuation,the interval power flow(IPF)is introduced into the integrated power flow,and solved with the affine Krawcyzk iteration to make sure that the range of active power setting of the UPFC not yielding the APLF.Compared with Monte Carlo simulation,the IPF has the similar accuracy but less time.
文摘为描述新能源发电等电力系统运行参数的不确定性对系统的影响,掌握系统的区间潮流分布,提出一种适于求解含新能源的交直流混联电力系统区间最优潮流(interval optimal power flow,IOPF)。源于区间优化法,将系统的新能源发电出力、节点负荷功率等不确定量表达为区间变量,引入到交直流混合系统最优潮流计算的非线性规划模型中,建立了区间最优潮流计算的非线性区间优化模型。根据区间匹配和区间极值取值等原理,将该区间规划转化为两个确定性的非线性优化问题,并采用现代内点算法求解,得到了区间最优潮流待求变量的边界信息。IEEE 14、118和300节点标准系统的计算结果表明,与蒙特卡罗模拟结果对比,所提出方法具有较高的求解精度,对IOPF目标函数区间半径和区间均值的计算误差不超过9%和0.8%,且易于实现、计算效率高,具有广泛的应用前景。