基于多态不确定性全时序仿真的微电网可靠性评估与规划

Reliability Evaluation and Planning of Microgrid Based on Whole Time Sequence Simulation of Multi-state Uncertainty

针对离网型光储(photovoltaic-energy storage system,PV-ESS)微电网的多态不确定性特征给可靠性评估和可靠性规划带来的挑战,提出了基于多态不确定性全时序仿真的可靠性评估方法及设备容量优化配置方法。首先,研究了离网型光储微电网系统的多态不确定性及其概率仿真模型,采用“故障−修复”时序模型模拟微型燃气轮机(micro turbine,MT)组设备的寿命过程,采用Beta分布密度函数模拟计及寿命特性的光伏电源出力特性,计及时变特性和随机波动特性建立了负荷综合时序模型,并建立了考虑运行约束的储能系统充放电模型。其次,综合概率指标、频率与持续时间指标定义了微电网可靠性指标体系,以可靠性最优为目标提出了电源调度与负荷削减策略,开发了基于多态不确定性全时序仿真的可靠性评估程序。最后,以改进的RBTS BUS6 F4馈线系统为运行场景,通过算例分析研究了微型燃气轮机、光伏、储能系统容量及功率对微电网可靠性的影响。计算结果表明:增加微型燃气轮机的容量可以持续提升可靠性水平,增加光伏容量对概率指标具有改善作用,但对频率和持续时间指标呈现非单调特性。根据光伏容量对可靠性指标灵敏度的影响,提出计及可靠性需求的MT-PV容量综合优化配置方法。可靠性指标在储能系统功率与容量坐标系内存在阶梯/饱和效应,通过定义和计算期望冗余功率可快捷、准确地确定储能系统(energy storage system,ESS)功率饱和区与ESS容量饱和区的边界功率值,形成可计及阶梯/饱和效应的ESS功率与容量配置方案。

The multi-state uncertainty of islanded photovoltaic-energy storage system(PV-ESS)microgrid poses the challenges to reliability evaluation and planning,therefore,the reliability evaluation method and equipment capacity optimization method based on multi-state uncertainty whole time sequence simulation are proposed.Firstly,the multi-state uncertainty and probability simulation model of islanded PV-ESS microgrid system are studied.A“fault-repair”time sequence model is used to simulate the life process of micro turbine(MT).The output characteristics of PV considering lifetime characteristic are simulated by the Beta distribution density function.The comprehensive time sequence model of load is established based on the characteristics of time varying and random fluctuation.A charge and discharge model of ESS with operational constraints is established.Secondly,the microgrid reliability index system is defined by integrating probability,frequency&duration indices.Aiming at the optimal reliability,the power dispatching and load shedding strategies are proposed,and the reliability evaluation program based on the whole time simulation of multi-state uncertainty is developed.Finally,by taking the improved RBTS BUS6 F4 feeder system as the operation scenario,the influences of the capacities of MT,PV and ESS on microgrid reliability are studied.As shown in the studies,reliability will be improved steadily along with the increase of MT capacity.The probability indices are upgraded by increasing PV capacity,while the indices of frequency&duration show non-monotone performance.According to the influence of PV capacity on the sensitivity of reliability indices,an MT-PV capacity optimization method is based on the reliability demand.In the coordinate of ESS energy capacity and power capacity,reliability indices are subject to ladder/saturation effects,and the boundary data between the power saturation zone and energy saturation zone can be determined by defining and computing the expected redundant power,following with the determination of optimized ESS capacities considering the ladder/saturation effects.