Abstract
Subsynchronous oscillation (SSO) phenomena caused by interactions between controllers of Doubly-fed induction generators (DFIGs) and series capacitor compensators has been well recognized. However, SSO can also happen on a DFIG-based wind farm without series compensation as reported in a recent real event. This paper firstly analyzes the recorded voltage waveform during this SSO event. Then an equivalent model of the system including the wind farm, static synchronous compensator (STATCOM) and the power grid was established. The paper derives the subsynchronous frequency response of the DFIG converter together with the STATCOM in detail and gives the criterion for SSO to occur, which is verified by both time domain simulation and spectrum analysis. The methodology adopted in this paper can be generalized to analyze the causes of a type of SSO that involves DFIGs and STATCOM but not series compensation. The paper also provides practical suggestions on adjustments of control parameters with the DFIG and STATCOM to prevent this type of SSO.
Highlights
In the recent decade, with the fast growth in the installation capacity of wind generation, subsynchronous oscillation (SSO) problems in wind farms were increasingly reported, threatening the stability and performance of power systems.Many recent works studied the modeling, mechanism analysis and mitigation on SSO phenomena in wind farms
SSO events on permanent magnet synchronous generator (PMSG) based wind farms were reported in China [18]–[22], which in characteristics are different from the Texas event
In this paper, an equivalent system model is established to analyze the mechanism of one type of SSO in a DFIGintegrated power system without series compensation
Summary
With the fast growth in the installation capacity of wind generation, subsynchronous oscillation (SSO) problems in wind farms were increasingly reported, threatening the stability and performance of power systems. Existing works on SSO focus on the subsynchronous control interaction between a DFIG-based wind farm and series compensation and influences from STATCOM. D. THE INFLUENCE OF RSC CONTROL PARAMETERS ON SSO 1) THE PROPORTIONAL COEFFICIENT OF THE CURRENT INNER LOOP IN RSC Based on the basic case, when the Kp2 changes, the SSO of the wind farm changes as shown in the Fig.. THE ANALYSIS BASED ON THE CRITERION 1) THE CURRENT INNER LOOP PROPORTIONAL COEFFICIENT OF STATCOM Based on the basic case, when the Ksp changes, the SSO of the DFIG-based wind farm changes as shown in Fig.. The results of the time domain simulation and the spectrum analysis verified that the criterion could accurately estimate the amplitude and frequency of the primary subsynchronous component in the line current. The active current iP and reactive current iR of the STATCOM at the PCC can be rewritten as iP
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