海岛无储能独立电网集成光伏与动态负荷的协调运行

As the maritime economy strategy was proposed, the standalone island grids that meet electrical energy requirement in development of island is gaining widespread studyies in the last couple of years. the oil gas master power generation based standalone grids integrated with ice storage without energy storage can be subjected to a high penetration level of distributed photovoltaic (PV) systems and dynamic loads. However, detailed stability analysis and, more importantly, reliability of operation for standalone island grid integrated with high penetration of PV systems and dynamic loads without energy storage, are not reported in current literature. To fill in this gap, this study presents integrated schemes for modeling, analysis and operation mechanism of standalone island grid with high penetration of PV systems and dynamic loads. Based on active/reactive power correlations between PV systems with dynamic loads, a coordinated operation scheme is used to control frequency by matching thermostatically controlled loads to generated power of PV systems and to provide the necessary reactive power support for the mitigation of large voltage variation on the feeder because of reverse power flow, intermittent solar radiation and load variation utilizing existing conventional reactive power banks retrofitted with inductive dynamic loads to realize the complementary functionality. One challenge is that the PV systems and dynamic loads is usually unbalance with much of which operating in single-phase mode, the traditional operation control strategy has difficult parameters adjusting and produces a large number of harmonic, causing that the dynamic voltage controller had been hardly to achieve good power dynamic compensation. The second challenge is the start-up procedure of induction motors in the weak island grid due to the limited inertia of the master generator. The assessment of these strategies is derived from simulations based on the Weizhou Island grid scenario with a capacity of 80MW in 2020. The research is providing an especially effective way to increase the hosting capacity of standalone island grid for PV systems, and provides the theoretical and practical basis to increase the reliability of standalone island grid.

随着我国海洋经济发展战略的提出，针对满足海岛资源开发的海岛独立电网的研究日益受到重视。涠洲岛建设新型海岛独立电网具有代表性，目前岛上供电主要依靠油气发电。预计2020年岛上峰荷功率8万千瓦，电力缺口很大。经过多方求证，大力开发分布式光伏发电，与目前的油气发电集成，采用冰蓄冷平抑光伏的功率和能量波动，成为一个可供选择的建设方案，但这需要首先解决无储能独立电网集成光伏与动态负荷的稳定运行问题。拟利用分布式光伏与动态负荷运行时有功/无功功率具有相关性，进行功率协调运行和互补性匹配设计，采用投切电容和动态负荷的感性无功抑制光伏出力变化引起的馈线电压波动，基于温控负荷匹配消纳光伏出力的方法消除频率偏移，研究侧重于单相运行分布式光伏和动态负荷的建模、电压稳定性分析及源网荷协同运行控制，这些问题的解决对于保障海岛电网高渗透率光伏接入的稳定运行具有理论意义和应用价值。

项目研究围绕4方面展开。.1、.微电网电源特性分析. 提出一种自励异步发电机自激建压稳定性快速分析方法。用复系数Routh表对发电机复系数状态矩阵方程特征值作判断，确定激磁电容容量与转子转速的量化关系，再用多时间尺度分析方法，得出自励异步发电机空载自激建压暂态稳定的临界条件及其特征解。. 研究了规则型、不规则型及离散型局部阴影对光伏阵列输出的影响。通过搭建SP、TCT、BL和HC结构光伏阵列仿真模型，获知各类阴影对光伏阵列的输出特性的影响程度。.2、微电网运行稳定性分析. 研究并搭建微电网的小信号模型，计算稳定运行状态初值，并用QR法计算状态矩阵A的特征值，分析特征值对系统特征模态的影响，判断系统的小干扰稳定性。. 研究无功功率优化模型中的凸松弛，解决海岛环状微电网无功优化模型的凸优化问题；建立多目标的混合整数无功优化模型，解决含多目标和混合整数的无功优化问题；建立可调节鲁棒优化模型，解决光伏出力不确定下的无功优化问题。.3、微电网潮流分析. 考虑目标函数、网损以及功率分配因子三者之间的相关性，建立带网损修正项的微电网线性化最优潮流模型，降低了计算误差，且保持了线性规划模型的在数值计算中的高效性和鲁棒性。.4、独立微电网电压及频率控制. 设计了一种低压无功功率分相动态补偿装置的硬件结构及控制程序，提出一种自动调压改变电容器补偿功率的策略，实现补偿容量的连续可调。. 提出一种基于温控负荷匹配光伏出力的稳频策略，通过仿真验证了该频率稳定控制策略的可行性。. 设计了一种带Z源网络的单相动态电压恢复器。设计了硬件结构以及一种基于简化情感控制的DVR控制器，提高了控制速度和补偿精度，能在电压暂降时分相快速稳定电压。. 提出了基于电力弹簧（ES）的微电网电压频率控制方法。设计了一种带Z源网络的单相ES电路结构及基于简化情感控制的ES控制器，用一组ES同时进行电压和频率控制。. 提出了一种基于简化情感控制器的微网P/V下垂控制策略，能更准确地均分系统功率，抑制功率振荡和减少电压波动。