基于灵敏度分析的电气耦合综合能源系统最小切负荷方法

Minimum Load Shedding Method of the Integrated Electricity-gas System Based on Sensitivity Analysis

切负荷是保证电力系统电压稳定的最后屏障。但随着电、气耦合程度的加深,电气耦合综合能源系统(integrated electricity-gas system,IEGS)中涌现出气压先于电压失稳的新场景,且切负荷种类已从电延拓为电、气2种。为实现IEGS整体切负荷量最低,需进一步考虑跨电、气2能源系统的最小切负荷需求。对此,提出了基于灵敏度分析的IEGS最小切负荷方法。首先,基于连续多能流定义综合灵敏度指标(comprehensive sensitivity index,CSI),以量化电、气负荷增长对IEGS气压的影响,CSI最大节点的气压最易达到稳定极限,可视为IEGS气压薄弱环节;基于此,构建切负荷灵敏度指标(load shedding sensitivity index,LSSI),评估切除各节点负荷对CSI最大节点气压的恢复效果,在气压临近失稳时按照LSSI由大到小顺序依次切除电/气负荷,使系统气压达到正常运行最低要求,实现负荷削减量最小;基于LSSI,引入切负荷成本形成考虑切负荷成本的灵敏度指标;最后,算例证明了相比切不灵敏节点,优先切灵敏度高的节点负荷可降低近60%的负荷削减量。

Load shedding is the last barrier to ensure voltage stability of a power system.However,with the deepening of electrical and gas coupling,a new case may arise that the gas pressure destabilizes before the voltage in the integrated electricity-gas system(IEGS),and the load shedding type has been extended from electrical load to electrical and gas loads.To achieve the minimum load shedding of IEGS,it is necessary to further consider the need for minimum load shedding across the electrical and gas energy system.Thus,an IEGS minimum load shedding method based on sensitivity analysis is proposed in this paper.Firstly,a comprehensive sensitivity index(CSI)is defined based on continuous multi-energy flow to quantify the effects of the increase in electrical and gas load on IEGS gas pressure.The maximum CSI gas pressure is the easiest to reach the stability limit,which can be regarded as the weak link of IEGS gas pressure stability.Then,a load shedding sensitivity index(LSSI)is constructed by evaluating the recovery effect of the load shedding on the maximum CSI gas pressure.When the gas pressure is approaching instability,the electrical/gas loads are removed in descending order according to LSSI so as to enable the gas pressure to meet the minimum requirements of normal system operation with minimum load shedding.Based on LSSI,load shedding cost is introduced to form the sensitivity index considering load shedding cost.Finally,the results of the case show that the load shedding of the nodes with high sensitivity can be reduced by nearly 60%compared with the nodes with low sensitivity.