Int J Performability Eng ›› 2020, Vol. 16 ›› Issue (11): 1708-1720.

### Unbalanced Harmonics under Hierarchical Control of Distributed Network Algorithm

Xusheng Yanga,b,*, Lizhen Wub and Xiaohong Haob

1. aLanzhou Petrochemical Polytechnic, Lanzhou, 730060, China;
bLanzhou University of Technology, Lanzhou, 730050, China
• Submitted on  ;  Revised on  ; Accepted on
• Contact: *E-mail address: yangxusheng00@163.com

Abstract: The centralized control has been played a very important role in the control structure of microgrids. With the multi-source and multi-inverter system in microgrids, accompanying a large number of unbalanced and nonlinear loads, the coordination between system models and data will be delayed or blocked; this will not only affect the data communication, but also seriously affect the power quality. In this paper, a novel networked hierarchical control approach for voltage unbalance and harmonics compensation is proposed based on the communication technology and hierarchical control theory and combined with a distributed consensus algorithm. The networked hierarchical control includes primary and secondary control. In the primary controller, some basic controls are proposed and modified, with the secondary controller to maintain the stable operation of the system. In the secondary controller, using the distributed consistency algorithm, the distributed secondary control (DSC) method is proposed to eliminate the deviations of voltage and frequency and also improve the nonlinear load power sharing among distributed generators (DGs). In this control structure, primary control and secondary control are combined, each DG is controlled independently, and the entire controller system is connected through a communication network. Compared with centralized secondary control, it reduces the system's requirements for high communication bandwidth and improves the system's reliability and expansion flexibility. The proposed approach not only compensates for the voltage unbalance and harmonic at sensitive load bus (SLB), but also improves the precision of power distribution and load current sharing. Finally, simulation and experimental results validate the effectiveness and feasibility of the proposed approach.