Open‐circuit fault‐tolerant operation of permanent magnet synchronous generator drives for wind turbine systems using a computationally efficient model predictive current control

Abstract

Model predictive fault-tolerant current control (MPFTCC) of permanent magnet synchronous generator (PMSG) drives can make a valuable contribution to improving the reliability and availability levels of wind turbines, because back-to-back (BTB) converters are prone to failure. However, MPFTCC suffers from excessive computational burden, because the BTB converter is treated as one system where all feasible voltage vectors (VVs) are used for prediction and evaluation. Accordingly, a computationally efficient MPFTCC algorithm for a PMSG drive is developed and proposed with the ability to handle insulatedgate bipolar transistor open-circuit faults. The candidate VVs of both machine-and grid-side converters are separately predicted and evaluated, which significantly reduces calculation effort. The proposed reconfigurable converter is a five-leg power converter with a common leg that connects the generator first phase to the grid three-phase, ensuring proper postfault reconfiguration of the grid-side inverter. Moreover, a three-switch rectifier is adopted to achieve fault tolerance of the PMSG-side rectifier. Performance of the considered MPFTCC strategies is evaluated by experimental means. 1 | INTRODUCTION Modern wind turbine systems based on direct-drive permanent magnet synchronous generators (PMSGs) with back-to-back (BTB) power converters have become a standard for wind turbine manufacturers, where the development of finite control set model predictive control techniques for both generator and gridconnection control has gained substantial interest in recent years. Although wind turbines have been exploited for more than 4 decades, their reliability and availability levels remain lower than expected [1]. The power converter of a wind turbine is usually associated with a failure rate higher than that of other applications [2]. Power switches are one of the main causes of critical failures [2,3]. In general, these can be divided into open-circuit (O-C) and short-circuit faults. Standard power converters include hardware protection against short-circuit failures, whereas there is no protection in the case of O-C failures. Numerous reliable fault-diagnosis techniques requiring no additional hardware have been proposed in the literature [4-13] for power switch O-C faults in BTB converters. The methods can be classified as current-based or voltage-based. Recently, diagnosis through adaptive thresholds was proposed in [10,11] and later improved in [12,13] with added sensor diagnostic capabilities. These approaches proved that compared with conventional fixed thresholds, an adaptive threshold enables very high immunity to false diagnostics under strong current transients and fast speed variations. Therefore, fault diagnostics are not the topic of this paper. Several topologies have been proposed to endow the gridside converter (GSC) with fault-tolerant capabilities. Redundant topologies have been proposed for creating a different paths for current flow by using TRIACs to connect an extra leg to converter legs [14] or to th...

A state‐of‐the‐art comprehensive review of modern control techniques for grid‐connected wind turbines and photovoltaic arrays distributed generation systems

“…Another modern MV-DMPC-based MSC CB [48] realizes a significantly better current quality by offering a smaller THD of 1.19% than the MPC-FTCC (i.e. 3.27%) [47]. However, the proposed control technique applies a sampling frequency of 10 kHz, which is higher than that used for the conventional methods [45,47].…”

“…The SC in the outer loop of MSC CB in Figure 5 operates the PMSG at the optimum ω r by controlling the reference q ‐axis current ( I * sq ) [47]. The extensively used control technique for the SC in the outer loop of MSC CB (Figure 5) is PI control [32, 45], which regulates the torque‐controlling reference q ‐axis current component ( I * sq ) as [32]: $$\begin{equation}I_{sq}^* = \left( {{K_P} + \left( {{{{K_I}} \mathord{\left/ {\vphantom {{{K_I}} s}} \right.$$…”

“…The advanced MPC‐FTCC with an open circuit fault‐tolerant capability for the MSC is proposed in [47]. Both the MSC and GSC are controlled separately in each sampling period to ensure a stable post‐fault operation of the WT.…”

“…Similarly, to avoid the traditional PI control [37], the modern SCs/QCs for the RSC CB are applied using adaptive backstepping control [38], FLC-sliding mode control (FLC-SMC) [39], H ∞ control [40], FLC-SMC using particle swarm optimization (PSO)-gravitational search algorithm (GSA) [41], recursive least squares (RLS) control [42], non-linear adaptive control (NAC) [43] and model-assisted active disturbance rejection control (MA-ADRC) [44]. The endorsed state-of-the-art CCs for the MSC CB are accomplished using wavelet-NN (WNN) control [45], integral SMC (ISMC) [46], MPC with fault-tolerant current control (MPC-FTCC) [47] and MPC [48]. Correspondingly, the advanced control techniques for the CC of RSC CB are PI-resonant (PIR) control [49], proportional-resonant (PR) control [50], H ∞ control [51], ISMC [52] and finite control set (FCS)-MPC [53].…”

Fault Analysis and Non-Redundant Fault Tolerance in 3-Level Double Conversion UPS Systems Using Finite-Control-Set Model Predictive Control

“…In back-to-back systems, another possible solution is the sharing of a converter leg between the two converters to improve the post-fault performance of the system [40,[56][57][58][59][60]. This effectively reduces the back-to-back converters to a 5-leg configuration but allows acceptable performance after a fault occurs.…”