计及电能质量影响的智能配电网孤岛划分策略

Island Separation Strategy of Smart Distribution Grid Considering the Effects of Power Quality Factors

现有智能配电网孤岛划分研究主要从功率平衡的角度出发,对电网安全约束考虑不充分,未考虑电能质量的影响,难以保证孤岛安全可靠运行。提出一种计及电能质量影响的智能配电网孤岛划分策略。故障后,首先计及联络开关进行网络连通性分析,进行初始孤岛划分。然后,对每个初始孤岛,建立切负荷-网络重构双层优化模型,并采用微分进化算法和混合粒子群算法求解,以降低搜索空间维数。具体地,在切负荷优化模型中,在允许频偏范围内充分发挥DG的调频特性,以减少负荷切除量;在网络重构优化模型中,建立包含频率约束、负序及谐波不确定性约束的电能质量综合约束集。提出基于序列二次规划法的配电网柔性潮流算法计算频率偏移条件下的孤岛潮流,引入点估计法进行负序、谐波不确定性分析,以改善孤岛的电能质量,提高其运行可靠性。最后,基于实际复杂配电网算例,验证了该策略的有效性和优越性。

Recent researches of island separation in smart distribution grid are usually analyzed in the view of power balance, while the effects of power quality factors, which may affect the safe and reliable operation of island, are not considered A new strategy of island separation considering the effects of power quality factors was proposed in this paper. Firstly, based on the network connectivity analysis, the original islands were divided by considering the tie-switches. For each original island, a two-layer optimization model of load-shedding and network reconfiguration, was established to decrease search space dimension and solved with evolution algorithm and improved hybrid particle swarm optimization algorithm. In load-shedding optimization model, frequency regulation characteristic of distributed generators was fully used to reduce load removal. In network reconfiguration optimization model, the comprehensive constraint set of frequency, uncertainty indices of negative sequence and harmonic components was established to improve the operation reliability of islands. A flexible power flow algorithm based on sequential quadratic programming was exploited to calculate the power flow under frequency deviation of each island Point estimate method was introduced to do uncertainty analyses of negative sequence and harmonic components. Via an actual complex distribution grid model, effectiveness and advantages of the proposed strategy were verified.