虚拟同步发电机的模型及储能单元优化配置

为了更好地将可再生能源接入配电网,针对并网逆变器的虚拟同步发电机(VSG)控制技术进行了研究。详细分析了VSG的数学模型和控制策略,在不同惯性和阻尼参数条件下,分过阻尼、欠阻尼和临界阻尼3种情况,提出了VSG附加储能单元优化配置的功率、能量和动态响应时间三大指标参数。结果表明:为了模拟同步发电机的惯性和阻尼,VSG需配置一定量的储能单元,其最小功率需求为所需要平抑的可再生能源波动功率的幅值,而其最小能量需求和动态响应时间均为与VSG惯性和阻尼参数相关的简洁表达式。最后,利用一台50kVA的VSG样机,验证了所提模型和控制策略的正确性和有效性。

Mathematical Model and Strategic Energy Storage Selection of Virtual Synchronous Generators

To better interface renewable energy resources (RERs) with the distribution network, the virtual synchronous generators (VSGs) are highlighted. An insightful analysis on the completely mathematical model and control scheme for the VSG is proposed in different virtual inertia and damping conditions. Additionally, according to the mathematical model, the optimal design of energy storage (ES) device of the VSG is achieved. It is found that, to emulate the inertia and damping features of the synchronous generator, an extra energy storage cell should be embedded in it. Besides, the optimal capacity of the ES is the power fluctuation of RERs VSG should suppress, and the desired energy of the ES is analytically decided by the virtual inertia and damping parameters of the VSG. Furthermore, the desired dynamic response time of ES is also obtained for VSG application. Finally, the experimental results obtained on a 50 kVA VSG prototype have verified the proposed model. This work is supported by National Basic Research Program of China (973 Program) (No. 2012CB215200) and Fundamental Research Funds for the Central Universities (No. CDJZR12150074, No. 106112015CDJXY150005).