基于模型预测的直流微网多电力弹簧协同控制策略研究

Cooperative Control Strategy of Multiple DC Electric Springs in DC Microgrid Based on Model Prediction

针对新能源接入、负荷投切所导致的直流微电网电压质量下降与系统呈现低惯性的问题,传统惯性控制随着电网规模的扩大适应性降低,因此提出一种多直流电力弹簧(DC electric springs,DCESs)单元下的直流微网电压协同控制策略,首先采用分布式一致性算法通过稀疏通信网络交换本地信息与相邻信息,求解全局母线电压平均值,并引入积分环节提高传统通信方式的收敛性。接着考虑系统负荷投切以及源侧功率波动导致的电压突变,基于DCES中的双向全桥DC/DC变换器构建预测模型,令各DCES根据系统功率波动状态自适应求解最佳虚拟电容值,平滑直流母线电压,提升了动态响应速度,同时分析了系统电压的收敛性与稳定性。最后通过MATLAB/Simulink在随机波动负荷、实际光伏场景下从电压质量、即插即用性能、系统惯性3个方面验证了模型的有效性,所提出的控制策略在保证系统电压平稳的同时,具有更优的动态响应能力。

For the problem of voltage quality degradation and low inertia of the power system caused by the high penetration of renewable energy access to the power grid and load switching,the adaptability of the traditional inertial control decreases with the expansion of the power grid scale.Therefore,a coordinated voltage control strategy of DC microgrid with multiple DCESs(DC electric springs,DCESs)is proposed.Firstly,the distributed consensus algorithm is used to exchange the local information and the adjacent information through the sparse communication network,offering the global average bus voltage.The integration link is introduced to improve the convergence of classical consensus methods.Considering the sudden changes of voltage caused by the system switching and the source-side power fluctuation,a predictive model is built based on the bidirectional full bridge DC/DC converter in the DCESs in order that each DCES can adaptively offer the optimal virtual capacitance value according to the power fluctuation state of the system,smoothing the dynamic response process of DC bus voltage.The convergence and stability of the system voltage are analyzed.Finally,the effectiveness of the model is verified through the MATLAB/Simulink in three aspects,i.e.the voltage quality,the plug-and-play performance,and the system inertia,under the random fluctuating loads and the actual photovoltaic scenarios.The proposed control strategy has a better dynamic response ability while ensuring the stable system voltage.