Journal of Shanghai Jiao Tong University ›› 2022, Vol. 56 ›› Issue (9): 1118-1127.doi: 10.16183/j.cnki.jsjtu.2021.415

• New Type Power System and the Integrated Energy • Previous Articles     Next Articles

Mechanism of Forced Subsynchronous Oscillation of Large-Scale Photovoltaic Power Generation Grid-Connected System with Series Compensation Tranmmission Lines

LIN Yong1, KANG Jiale2, YU Hao1, CHEN Honglin1, YANG Yanji3, CHEN Wuhui2()   

  1. 1. Grid Planning and Research Center, Guangdong Power Grid Co., Ltd., Guangzhou 510080, China
    2. College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, China
    3. School of Electrical and Information Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China
  • Received:2021-10-18 Online:2022-09-28 Published:2022-10-09
  • Contact: CHEN Wuhui


There exists the subsynchronous oscillation (SSO) instability risk in large-scale photovoltaic(PV) grid-connected systems with series compensation, which is generally explained by the negative damped oscillation theory. In this paper, the inter-photovoltaic harmonics due to maximum power point tracking (MPPT) control are used as the disturbance source and the large-scale PV grid-connected system with series compensation as the forced system. The forced oscillation theory is used to reveal the SSO mechanism of PV power generation based on the interaction between the perturbed MPPT and the series compensation grid-connected system, and verified in the PSCAD/EMTDC simulation platform. The results show that the perturbed MPPT-based PV inverter outputs interharmonic currents to the system due to the modulation coupling on the AC-DC side, which may lead to serious forced SSO problems when the interharmonic frequency is close to the frequency of inherent weakly damped mode of the system, causing a shock to the system stability. The simulation results verify the correctness of the proposed theory.

Key words: photovoltaic(PV), interharmonic, subsynchronous oscillation(SSO), forced oscillation

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