Experimental design of a new fast sensorless control of DFIG in complex domain

Abstract

In this study, a new robust sensorless control of doubly-fed induction generator (DFIG) in the complex domain has been investigated. The proposed sensorless control is based on the extended complex Kalman filter (ECKF) and proportionalintegral complex controller. The design of this sensorless control in the complex domain allowed a threefold objective: a decrease in the system's dimension by half, an optimisation in the implementation of the control strategy and a decrease of the CPU computational time. In fact, to obtain the latter, the dimension of the DFIG model involved in this control has been halved, which leads to a reduction in the control's schema. Moreover, all the matrices involved in the ECKF have smaller dimensions than those of the real extended Kalman filter and no matrix inversion is needed because the output of the system is a scalar variable. The proposed sensorless control has been tested experimentally for several operating points, namely: nominal operation, operation under asymmetrical voltage dip and parameter variations. Moreover, the observability of the complex state model has been analysed and the required conditions for the local weak observability have been defined. The experimental results confirm the theoretical study and show a good reliability and a high rotor speed estimation accuracy.

Sensorless MRAS control of emerging doubly‐fed reluctance wind generators

“…The higher mean Δ𝜃 r ≈ 4 • , with θr taking part in Equations ( 17) and (18), is another contributing factor to the îs digression. It is important to point out that Δ𝜃 r , which is carried over to the secondary frame angular misalignment (Δ𝜃 s ) given Equation (26), is exclusively a consequence of Lp underestimation according to Equation (24) as detailed in Section 4.2. Although the accuracy of îs and θr estimates has worsened compared to the situation in Figure 7, the controller performance do not appear to be influenced by the relatively small Δ𝜃 s ≈ 4 • incurred as demonstrated by the P p ≈ i sq and Q p ≈ i sd responses, which precisely follow their set points in a decoupled fashion.…”

“…However, the utilisation of shaft encoders for voltage or flux oriented VC undermines the mechanical robustness and reliability. The development of rotor position and/or speed estimation techniques for sensorless operation of both DFIG [21][22][23][24] and BDFRG [25][26][27][28] has been getting increasingly popular for this reason.…”

Effective Direct Power Control for a Sensor-Less Doubly Fed Induction Generator with a Losses Minimization Criterion

“…The relationships (44) and (45) The sensitivity of stator voltage to the noise is very high in case that no precautions are taken during the measurement. The accompanied noise will be magnified if the pure integration is applied, and finally the estimated flux quality is deteriorated.…”

“…A lot of attempts were made to increase the robustness of the estimator against the parameters' variations (mainly the stator resistance), but this has resulted in increasing the system complexity via adding extra computation parts to the system [42,43]. In [44,45], the extended kalman filter has been introduced for estimating the speed and rotor position for the DFIG. The problem with the kalman filter was that it considered the linear models of the system and observer, which was not so precise especially when applied with highly non-linear system such as the DFIG; adding to this, was the complexity of the system.…”

Sensorless variable speed operation of doubly‐fed reluctance wind generators

“…Avoiding such sensors would enhance the reliability and lower the maintenance of DFIG wind turbines in particular, as frequent and disruptive brush replacements could otherwise increase their failure rates [21]. This fact has mainly initiated the growing interest and advances in encoder-less control of DFIGs over the last few years [4,[26][27][28][29][30][31]. Strongly parameter-dependent and complicated models have hindered any notable developments in this direction for the BDFIG [1,2] until very recently [32][33][34].…”