计及需求响应的含高比例光伏配电网无功电压综合控制方法

在大力推动新型电力系统建设的背景下,针对高比例光伏接入导致的配电网过电压问题,对现有过电压解决方案,包括网络参数调节、有功调节、无功调节等手段进行进行系统性分析对比,进一步采用不影响新能源消纳且经济性较高的方式,即价格型需求响应与光伏无功调控相结合的过电压治理方案。首先,获取变压器下所接各用户的需求响应弹性系数,在电压不越限、售电电价介于合理范围及光伏就地消纳的约束下,以电网公司开展需求响应的代价最小化为目标,建立配电网综合无功电压优化模型,并使用粒子群算法进行求解;最后,在改进的IEEE33节点系统上进行仿真分析,仿真结果证明,该无功电压综合控制方法可在充分考虑用户需求响应弹性的基础上进行光伏消纳,调压效果兼具有效性和经济性。

计及配网电压越限的光储协同优化运行策略

随着大量分布式光伏(distributed photovoltaic,DPV)并网,目前配电网中出现了日间过压和夜间低压并存的电压越限问题,并进一步影响了网络的经济运行。本工作基于此提出了两阶段光储系统协同运行的优化调度策略。该策略第一阶段通过计算节点的电压灵敏度来确定待调节的储能节点与充放功率,以及光伏可调节点;第二阶段建立了光储运行优化模型。该模型以储能的调度成本、购售电成本以及网损成本之和最小为目标,以网络潮流、节点电压、储能SOC(state of charge)、光伏的无功可调容量等作为约束,通过粒子群算法对该模型进行求解,可以得到光储系统日调度出力策略。最后,以某地区31节点的实际配电网作为算例,验证了本工作方法的有效性。算例结果表明,该策略可以通过光储的协同调度,有效治理电网中的电压越限问题,并且在保障配电网电压安全的同时,实现优化运行成本的目标。

计及负荷特性的配电网多时间尺度电压控制及协调修正

针对第三方光伏电源大量并入配电网的市场背景,提出了一种计及负荷特性及光伏无功成本的配电网电压协调控制方法。该方法分为日前优化和实时优化两个阶段。日前优化以网损及有载调压变压器和并联电容器组动作成本最优为目标,优化产生未来24h有载调压变压器分接头和并联电容器组动作方案;日内优化中建立了光伏电源无功输出成本模型,以网损和光伏无功成本最优为目标,通过优化光伏无功输出消除预测误差产生的影响,并增加了对日前优化的校正环节。同时,为了能在工业负荷和商业负荷占比较高的地区达到更好的优化效果,在无功优化中考虑了负荷静态电压特性,建立了考虑负荷特性的潮流计算模型,改善了优化效果。通过实例仿真表明,所提出的协调控制方法能够很好地消除预测误差对实时运行的影响,平抑电压波动,减少控制成本。

Design of Capacitor Bank in Parallel to Photovoltaic Power Plant

The purpose of the paper is to develop a solution for application of PV （photovoltaic） generators in MV （medium voltage） distribution system without unacceptable voltage changes due to drops of PV power output. The proposed solution includes operation of PV with predetermined leading power factor and addition of a capacitor bank in parallel to PV plant in order to compensate the reactive power absorbed by the PV inverters. The analytical expression of required power factor angle is derived. Adding a capacitor bank in parallel to PV power plant may pose a problem because of space limitations. The dimensions and cost of small MV capacitor banks depend significantly on the capacitor bank protection against internal faults. Application of the developed negative-sequence current difference method for the unbalance protection of the capacitor banks enables to achieve a compact and cost-reduced design of the banks connected in parallel to PV power plants. A real-world example of operation of the PV plant in parallel to the capacitor bank with the novel protection scheme is described.

Effectiveness of Optimal Arrangement of the Residences Operated by Reactive Power Control for a Clustered Grid-Interconnected PV System

There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. However, there are not many types of inverters that can operate reactive power control because there are insufficient effects on a low voltage distribution line with low penetration PV with reactive power control. Therefore, it is necessary to consider how to increase generation efficiency with a lower number of inverters. In this paper, four Japanese standard distribution line structures, for example of a residential area on ＂C1＂, where 2,160 residential PV systems are grid-interconnected, are selected. The optimal setting of reactive power control at each residence is computed on the distribution lines with a greedy method.

Grid-Connected PV Solar Energy Converter with Active and Reactive Power Control

This work proposes a 12 kW three-phase grid-connected single stage PWM DC-AC converter destined to process the energy provided by a photovoltaic array composed of 57 KC200GT PV modules with high power factor for any solar radiation. The PWM inverter modeling and the control strategy, using dqO transformation, are proposed in order to also allow the system operation as an active power filter, capable to compensate harmonic components and react power generated by the non-linear loads connected to the mains grid. An input voltage clamping technique is proposed to impose the photovoltaic operation on the maximum power point. Simulation and experimental results are presented to validate the proposed methodology for grid connected photovoltaic generation system.