Controller Strategy for Open-Winding Brushless Doubly Fed Wind Power Generator With Common Mode Voltage Elimination

Abstract

This paper presents the theoretical derivation and implementation of a novel direct power control for open-winding brushless doubly-fed reluctance generator (OW-BDFRG). As one of the promising brushless candidates, the OW-BDFRG is characterized with two stator windings fed by a dual controllable two-level three-phase converters through a common DC bus with common mode voltage elimination. The parameter-free control strategy is designed to obtain maximum power point tracking with variable speed constant frequency (VSCF) for wind energy conversion systems (WECSs). Compared to the traditional three-level converter systems, the DC bus voltage, ACside voltage and capacity ratings of the proposed converter system are notably high while the reliability, redundancy and fault tolerance are significantly improved. Effectiveness, correctness and robustness of the proposed control strategy and the common mode voltage elimination scheme are evaluated and confirmed through simulation and experimental tests on a 42 kW generator prototype typical for VSCF-WECS. Index Terms-Brushless doubly-fed machines, power control, common mode voltage, open-winding, variable speed constant frequency, maximum power point tracking. NOMENCLATURE u p , u c Power, control winding phase voltages [V] i p , i c Power, control winding phase currents [A] R p , R c Power, control winding resistances [Ω] p p , p c , p r Power, control and rotor pole pairs L p , L c Power, control winding self-inductan. [H] ψ p , ψ c Power, control winding flux linkages [Wb] ψ pc , L pc Mutual flux [Wb] and inductance [H] f p , f c , ω p , ω c Power, control winding frequencies [Hz] and their angular frequencies [rad/s]

Dynamic analysis and oscillation elimination of brushless doubly fed wind power generation system during symmetrical voltage dips

“…In the diagram above, L sp and L sc are the equivalent selfinductances of PW and CW, and M pc is the equivalent mutual inductance between PW and CW [25]. The voltage of the CW is a controllable voltage source that is controlled by the command signal…”

A Zero-Sequence Steerable CBPWM Strategy for Eliminating Zero-Sequence Current of Dual-Inverter Fed Open-End Winding Transformer Based PV Grid-Tied System With Common DC Bus

“…According to (6), (7) and 9, the magnitude and phase relationship between the reference voltage vector V 1_ref , V 2_ref and V ref can be deduced and expressed as follows…”

Model predictive virtual power control of brushless doubly‐fed induction generator for fast and smooth grid synchronisation

“…As PW current is zero when PW of BDFIG is open-circuited, the PW flux, rotor flux, and CW flux are chosen as state variables to ensure the possibility of unified control during the grid synchronisation mode and the grid-connected mode. The statespace equation of BDFIG can be derived from the above dynamic equations as sX = AX + BV (8) where s represents the differential operator, X = [ψ sp ψ r ψ sc ] T are the state variables, and V = [u sp u r u sc ] T are the stator and rotor voltage vectors,…”

“…Tremendous efforts have been exerted in the control of BDFIGs to facilitate its development [8][9][10][11][12][13][14][15]. However, most of the studies have addressed the control issues of BDFIG in either standalone or grid-connected operation.…”