The increasing penetration of offshore wind power generation promotes the revolution of wind turbine toward high-power application. The development of high-power wind turbine undoubtedly poses new technical challenges. This article presents a comprehensive overview for high-power wind energy conversion system (WECS) from key technique aspects, including topologies, stability, reliability, and ancillary service capability, and further investigates the key challenges and potential solutions. The various topologies of power converter applied in high-power wind turbine are first reviewed and discussed. The different semiconductor technology, including recent wide bandgap devices, and their potential contributions for offshore high-power converters are discussed. Furthermore, the potential stability issues of high-power WECS are investigated and reviewed. Also, the stabilization control strategies are discussed. Further, the reliability issue and enhancement strategies of high-power WECS are discussed, including condition monitoring, active thermal control strategy, and fault-tolerant operation method. In addition, the ancillary service capability of high-power WECS, including frequency-active power control capability and voltage-reactive power control capability, is reviewed. Finally, the future trends and potential solutions are discussed in this article.

This article presents an advanced fault ride-through control strategy based on model predictive control (MPC) of high-power wind turbine (WT), which is able to provide voltage support for power grid under symmetrical and asymmetrical grid faults. An optimal cost function is first established to realize multi-objective control of wind power converter, considering current regulation, neutral-point voltage balance, and switching frequency control. The flexible positive and negative sequence control (FPNSC) method is applied to generate the current references complying with converter current and voltage limitations. Simulation and hardware-in-the-loop experimental verification are implemented to validate the effectiveness of the proposed fault-ride through operation strategy. The verification results show that the proposed strategy is able to effectively support voltage and implement fault ride-through (FRT) during grid faults with optimized neutral-point voltage and average switching frequency. The proposed MPC strategy can address different fault conditions with good adaptivity. It thus enhances the operation performance of high-power WT during faults events.

In renewable energy based systems Grid-Connected Voltage Source Converters (GC-VSC) are used in many applications as grid-feeding converters, which transfer the power coming from the renewable energy sources to the grid. In some cases, the operation of GC-VSC may become unstable or uncontrollable due to, among others: a grid fault or an inappropriate current-power reference, that give rise to fast electrical transients or a saturation of the controller. In this paper, an improved control scheme is proposed to enhance the controllability of GC-VSC in all these situations. This solution consists of two parts, on the one hand a new Proportional-Resonant (PR) controller with anti-windup capability to be used as current controller, and secondly a new current/power reference modifier, which defines the suitable reactive current/power reference to keep the system stable. It is worth to mention that the proposed scheme does not need information about the grid parameters as it only uses the converter current, and the voltage at the capacitors of Inductor-Capacitor (LC) output filter.

This paper presents a grid synchronization structure for a current-controlled voltage source converter (VSC), known as an adaptive vector grid synchronization system (AVGS). The main blocks of the system are a pre-filter stage, consisting of a filtered quadrature signal generator (FQSG) and a vector-based phase-locked loop (VB-PLL) with adaptive gains. AVGS allows fast detection of magnitude, frequency, and phase of the three-phase grid voltage, and enables the accurate separation of its symmetrical components meeting the transient operating requirements imposed by grid codes. The system rejects disturbances, such as voltage harmonics or imbalances, and improves transient stability with grid faults. A previous publication analyzed the small-signal stability of the synchronization system. The excellent behavior of the proposed system is verified through experimental tests carried out on a 2 MW wind power converter. The evaluation is performed in a dedicated test bench (FC PT0022) specifically designed to enable rated-power testing and high-fidelity emulation of grid disturbances.

The high-power grid-connected inverter (GCI) plays a key role in integrating wind power generation. The finite control set model predictive control (FCS-MPC) has emerged as a promising high-performance control strategy for this class of power converters. However, practical stability assessment of GCI with MPC has not been fully addressed. This article investigates the stability of high-power GCI controlled by MPC and its application in offshore wind farm. The frequency scan technique is employed to derive the impedance characteristic of MPC-enabled inverter. Then, effects of MPC parameters and operating conditions on passivity are investigated. The proposed control strategy is validated and compared with classical PI-based control within Alpha Ventus offshore wind farm. Simulation and hardware-in-the-loop (HiL) verification are both implemented. The employed HiL setup integrates dSPACE DS1006 and PLECS RT Box 1, providing a versatile real-time testing platform for independent validation of the controller and plant model. The study findings show that MPC strategy can effectively mitigate oscillation phenomena and enhance stability of offshore wind farm under weak grid conditions. Hence, the proposed MPC strategy is a promising solution to promote penetration of offshore wind power generation into power system