A New Sensorless Speed Control Scheme for Doubly Fed Reluctance Generators

Abstract

Abstract-The paper presents the development and experimental validation of a novel angular velocity observer-based fieldoriented control algorithm for a promising low-cost brushless doubly-fed reluctance generator (BDFRG) in wind power applications. The BDFRG has been receiving increasing attention because of the use of partially-rated power electronics, the high reliability of brushless design, and competitive performance to its popular slip-ring counterpart, the doubly-fed induction generator (DFIG). The controller viability has been demonstrated on a BDFRG laboratory test facility for emulation of variable speed and loading conditions of wind turbines or pump drives.

Design and Modeling of Brushless Doubly-Fed Reluctance Generator for Wind Mills

“…To supply and furthermore get the slip power, the rotor of the generator is able along with it tends to be driven at sub-synchronous, synchronous or progressively synchronous rates. Utilizing the BDFRG space-vector model, the accompanying steady-state connections for the primary mechanical power and reactive power could be fixed: (13) (14) VC of Pp and Qp is linked as both the isd and isq auxiliary current presented in (13) and (14). The level of linking could be decreased by adjusting the qp-axis of the reference frame to the main voltage vector.…”

Encoderless flux vector oriented control of brushless doubly-fed reluctance generators

“…Given 1, such frame choice facilitates control as the secondary dq currents are then DC. The flux FOC forms of (3), and the respective torque and 3-phase reactive power expressions, now become [27]- [31]:…”

“…Therefore, apart from R p (through λ p ) with smaller machines, the use of (12) only needs the L p knowledge. Yet, as θ s can still be affected by measurement noise, the raw θ r = θ p + θ s values are passed through a common load-model based PI observer [31], [32] to eradicate erroneous estimates for accurateω rm predictions. The filteredθ r is fed back to further enhance the quality ofθ s estimation, the emanating PWM signals, and in turn the controller response.…”

“…This expression is implemented using a commercial Parker DC drive operated in torque mode. The other relevant details about the BDFRG test facility can be found in [24]- [31].…”

“…However, these conveniences often come with some performance trade-offs by introducing the inevitable machine model reliance necessary for the position or speed estimation as demonstrated in the DTC case [19]. An exception is the latest development of a viable speed sensorless FOC scheme in [31], which has been shown to possess good disturbance rejection capabilities and smooth response using the maximum torque per inverter ampere strategy [18]. This paper is an extension to the work in [31] by presenting the principles and experimental results of reactive power control implementation on a custom-built BDFRG for speed dependent WECS-alike loading profiles.…”