谐振约束下含功率因数校正电容新能源集群最大渗透率接入研究

Research on Maximum Penetration Level of Renewable Energy Group With Power Factor Correction Capacitor Considering Harmonic Resonance Limits

随着谐振频段不断提高,基于基频设计的功率因数校正电容C高频段容抗特性对电网等效阻抗的影响不可忽略,不同节点差异化非基波成分C容抗诱发谐振,成为新能源接入水平提高的瓶颈。该文以新能源集群接入IEEE 9节点区域微网为对象,首先建立区域微网阻抗模型,并通过全频段网侧阻抗特性波特图,分析功率因数校正电容C对网侧阻抗特性影响。接着,结合逆变器阻抗,基于源网阻抗适配原理揭示并网系统潜在谐振的机理。在此基础上,通过在并网点模拟谐波负值电容以抵消谐波容抗Z引入对并网系统稳定性的影响,提出无需增加额外检测电路的基于谐波负值伪电容的软件改进方案。在单节点新能源运行能力提高的基础上,以谐振为约束研究区域微网新能源集群渗透率最大接入节点的选取。最后,仿真和小规模实验验证了上述研究的正确性和可行性。

With the continuous improvement of resonance frequency, the influence of the capacitance characteristics of power factor correction capacitor based on fundamental frequency design on the equivalent impedance of power grid can not be ignored. The capacitance impedance of diversified nodes with non fundamental components induces resonance,which becomes the bottleneck of improving the injecting level of renewable energy. In this paper, an IEEE 9-node regional microgrid with renewable energy group interfaced was taken as the study object. Firstly, the impedance model of regional microgrid was established, and the influence of power factor correction capacitor CPFC on the impedance characteristics of grid side was analyzed through the Bode diagram of impedance characteristics of full frequency band. Secondly, combined with the inverter impedance, the potential resonance mechanism of grid-connected system was revealed by using the impedance matching principle in source-grid side. On this basis, an improved scheme of harmonic negative pseudo capacitor without additional detection circuit was proposed by simulating harmonic negative capacitor at point of connecting to eliminate the influence of the harmonic capacitance impedance ZCPFC_H on stability. Then, the selection of the injecting node with the maximum penetration of renewable energy group in regional microgrid was researched with the limitation of harmonic resonance. Finally, the correctness and feasibility of the above research were verified by simulation and small-scale experiment.