Design of a nonlinear backstepping control strategy of grid interconnected wind power system based PMSG

Maximum power point tracking (MPPT) techniques had evolved rapidly in the last decade with the evolution of power electronics. This paper presents a control technique for a variable speed, grid connected direct driven permanent magnet synchronous generator (PMSG). The PMSG is connected to the grid through three-phase diode rectifier followed by a boost converter controlled with the MPPT technique to maintain a constant DC bus voltage for different wind velocities. The paper compares between two MPPT techniques, HCS and fuzzy logic. The control depends upon sensorless rotor speed estimator through measuring the input dc voltage and current for the boost converter. The system performance is investigated using a MATLAB/ SIMULINK model for 2 MW PMSG wind turbine.

The microgrid (MG) technology integrates distributed generations, energy storage elements and loads. In this paper, dynamic performance enhancement of an MG consisting of wind turbine was investigated using permanent magnet synchronous generation (PMSG), photovoltaic (PV), microturbine generation (MTG) systems and flywheel under different circumstances. In order to maximize the output of solar arrays, maximum power point tracking (MPPT) technique was used by an adaptive neuro-fuzzy inference system (ANFIS); also, control of turbine output power in high speed winds was achieved using pitch angle control technic by fuzzy logic. For tracking the maximum point, the proposed ANFIS was trained by the optimum values. The simulation results showed that the ANFIS controller of grid-connected mode could easily meet the load demand with less fluctuation around the maximum power point. Moreover, pitch angle controller, which was based on fuzzy logic with wind speed and active power as the inputs, could have faster responses, thereby leading to flatter power curves, enhancement of the dynamic performance of wind turbine and prevention of both frazzle and mechanical damages to PMSG. The thorough wind power generation system, PV system, MTG, flywheel and power electronic converter interface were proposed by using Mat-lab/Simulink.

SummaryDue to the stochastic and unpredictable nature of wind speed, extraction of maximum power from the wind turbine system becomes an attractive control objective. Therefore, to capture more wind power, various conventional maximum power point tracking (MPPT) schemes are developed for standalone small‐scale variable speed wind power generation system (VSWPGS). This manuscript proposes novel adaptive step size (ASS) and drift‐free ASS (DF‐ASS) MPPT methods for a permanent magnet synchronous generator (PMSG)‐based VSWPGS. The control schemes achieve maximum power point (MPP) without using mechanical sensors like speed encoder and anemometer. The proposed MPPT controllers are implemented on a laboratory‐scale DC motor‐PMSG‐based wind power generation system (WPGS) using OPAL‐RT real‐time digital platform. The ASS and DF‐ASS methods capture more power, reduce the steady‐state power oscillation around MPP, and improve the tracking speed. Also, the proposed DF‐ASS control scheme avoids drift phenomenon during wind speed increase condition. The comparative experimental results of proposed ASS and DF‐ASS methods with respect to the fixed step size MPPT schemes show better dynamic and steady‐state performance, making it pertinent for small‐scale WPGS.

This paper reviews the existing models, connection schemes and maximum power point tracking (MPPT) methods of PV arrays. The partial shading causes significant power losses. It is very difficult to maintain uniform irradiance over the entire PV array, especially for rooftop or building-integrated PV systems. The aspects such as connection scheme of PV array, shading pattern and maximum power point tracking (MPPT) techniques, etc., decide the power generated by the PV array. The conventional MPPT methods are only capable of reaching maximum power point (MPP) in identical insolation situations. Hence, conventional MPP tracking becomes inept due to the existence of several peaks in the P-V characteristics. There are different global maximum power point (GMPP) tracking techniques available in the literature that operate in partial shading scenarios. The reconfiguration of the PV array reduces the number of multiple peaks. This reduction in several peaks makes conventional MPP tracking techniques competent even under partial shading conditions with low implementation complexity and higher tracking speed. This paper can assist scientists in choosing a precise objective-based PV module model, connection schemes and MPP tracking methods out of numerous schemes available in the literature.

In recent years, renewable energy generation has become a suitable choice for distributed energy systems. Among several sources of renewable energy, the demand for wind energy is increasing at an exponential rate, due to its advantages such as being environmentally clean, abundant availability, and so on. In this scenario, a variable speed wind energy system (VSWES) is mostly preferred in the distribution system as it captures more energy from the available wind speed. For VSWES doubly-fed induction generator (DFIG) or permanent magnet synchronous generator (PMSG) is widely adopted. For small-scale applications in the distribution system, the PMSG based standalone VSWES has attracted much interest due to its immense advantages, such as gearless construction, absence of external supply for the rotor field, large power density, low noise, high efficiency, and less maintenance. In the VSWES, to capture more power and to enhance the system performance different maximum power point tracking (MPPT) algorithms are introduced by the authors. These existing MPPT algorithms are implemented with two-stage power electronic converters, that is, an uncontrolled ac-dc converter along with a dc-dc converter used in the system. Here, in this chapter, the mathematical modelling of wind turbine (WT) and PMSG are analysed. In addition to capture maximum power, a dc-dc boost converter is designed. The maximum power point (MPP) is determined with the gradual increase of the duty cycle and the respective characteristics are plotted. To verify the MPP, the system incorporates a speed sensor dependent and speed sensorless conventional P&O MPPT methods are done using MATLAB\Simulink software. The results are analysed, which ensures the satisfactory performance of wind turbine system (WTS) under wind speed and load change scenarios.

Today wind energy has emerged as an alternative energy source for power generation. This paper investigates about standalone Permanent Magnet Synchronous Generator (PMSG) based wind energy conversion system (WECS) with Maximum Power Point Tracking (MPPT). The proposed system comprises of Wind turbine (WT), PMSG, boost converter, uncontrolled diode rectifier, battery bank, bidirectional buck boost converter and dc load. Multi pole PMSG is best suited for low speed, wide range variable speed wind energy applications. Wind flow varies with time; as a result power produced also varies. As maximum power has to be tracked for varying wind speeds, perturbation & Observation (P&O) algorithm is implemented for MPPT. Battery storage system is essential to supply the load during low wind speed condition. In this paper, a simulation study of the proposed standalone system is done using SIMULINK in MATLAB.

In renewable system control engineering, Maximum Power Point Tracking (MPPT) techniques are considered as one of the key steps in photovoltaic (PV) system development. Indeed, some MPPT techniques provide high performance under uniform irradiation and temperature conditions. However, their performance significantly degrades when the two preceding climatic conditions suddenly change. Therefore, this paper proposes a new voltage regulation based on Fuzzy Logic Control (FLC) strategy and small-signal model of DC–DC booster converter. The proposed control scheme is mainly based on the indirect incremental conductance (Inc) technique, equipped with an optimal integrator controller (OIC). It is implemented in a PV system, consisting of a DC–DC boost converter connected to a resistive load, with the main objective of ensuring a good MPP tracking behavior for variable operating conditions. To achieve this objective, the proposed MPPT strategy is designed around two stages. First, the smooth reference voltage is ensured by a Single-Input Single-Output (SISO) fuzzy logic controller using the Inc technique based on the MPPT approach. Then, the optimal integrator controller stabilizing the closed-loop system is integrated with optimization of its parameter according to Routh’s criterion for resistive load variations. Simulation results confirm the effectiveness of the proposed MPPT technique compared to some commonly used MPPT approaches. The superiority of the proposal is proven by using efficiency ratio, which rises more than 98% in all case studies. These objectives are ensured for both uniform and critical sudden change in weather conditions, regardless of resistive load variations.

The field of small scale distributed wind energy generation features noticeable concern regarding the utilization of direct driven permanent magnet synchronous generators (PMSGs). The quality of the output power from a wind turbine generator is mainly dependent on how the maximum power point is tracked. Classical hill-climbing maximum power point tracking (MPPT) techniques exhibit inherit oscillation/settling time tradeoff. Wind MPPT process can be considered as an event driven problem. This paper proposes a Stat-Flow based Hill Climbing Searching (HCS) wind MPPT as a competitive technique. The presented technique features simplified implementation, more degree-of-freedom, controllable event timing. Those features contribute to enhance the MPPT process by minimizing the steady-state power oscillations and improve the transient performance. Rigorous simulations are carried out to examine the proposed technique under various wind speeds and power levels to validate the technique's effectiveness.

Permanent magnet synchronous generator (PMSG) wind power generation system is a new type of wind power system. Cascaded multilevel inverter has extensive application in the high voltage converter system for its numerous advantages. Using cascaded multilevel inverter instead of the traditional two-level inverter can well meet the high power and reliability requirements of direct-driven wind power generation system. Carrier phase shifted sinusoidal pulse width modulation (CPS-SPWM) control strategy can reduce the output harmonics effectively, du/dt and current ripples. In this paper, CPS-SPWM control strategy for cascaded multilevel inverter applied in PMSG wind power system is proposed. The system model of cascaded H-bridge inverter based on CPS-SPWM has been built by using MATLAB. The simulation results show that the presentation of cascaded H-bridge inverter based on CPS-SPWM for direct-drive wind power generation system is feasible.

This paper presents control strategies of a back-to-back converter (BtBC) based grid connected wind turbine (WT) system using permanent magnet synchronous generator (PMSG) under varying wind velocity. A vector control (VC) scheme is adopted to regulate BtBC, which consists of two 3-phase converters i.e. Machine Side Converter (MSC) and Grid Side Converter (GSC). Maximum Power Point Tracker (MPPT) is playing a very important role for controlling of MSC to extract maximum power from wind and hence perturb and observe (P&O) algorithm based MPPT is used. In order to protect the WT-system at above rated wind velocity, blade pitch angle algorithm is also incorporated with the study system. For simulation MATLAB/Simulink software is used. Simulink results are obtained under varying wind velocities i.e. rated-above rated-rated-below rated wind speed and those results are analyzed in details.

Wind power generation system has characteristics of high nonlinear and stochastic. In this paper, power control strategy of permanent magnet synchronous wind power generation system is investigated to realize power adjustment under full wind speed conditions. For the wind power generation system operating under rated wind speed, the inverse system is constructed for the nonlinear dynamic model of the system. Then, an exact linearization feedback controller is constructed to achieve maximum power point tracking. When the wind speed is higher than the rated speed, a variable pitch controller is proposed by the usage of inverse system method. A pitch angle control module is employed to ensure the rated power output and limit rotor speed. Based on the maximum wind energy capture and the constant power control, the all operating regions control of permanent magnet synchronous wind power generation system is discussed. The continuous of the controller is analyzed. Simulation results show the effectiveness of the proposed control strategy.

The present paper aims to design shunt active power filter (APF) for harmonic cancelation of grid-connected wind turbine (WT). The wind energy conversion system (WECS) consists of permanent magnet synchronous generator (PMSG) driven by a variable-speed WT. The output of the PMSG is connected to a direct three phase AC/AC matrix converter (MC) to interface the system with the distribution grid. The MC controls the wind maximum power point tracking (MPPT) via perturbation and observation (P&O) technique. The MC output current harmonics and harmonics of non-linear load are canceled by the proposed shunt APF based on d-q theory. The system under study is simulated using MATLAB/SIMULINK platform. The digital results prove that, the suggested system can submit the generated wind power to the grid without currents/voltages harmonic distortion at grid side, it can also satisfactory eliminate the non-linear load harmonic currents. The system dynamic performance is investigated under different wind speed and loading conditions. The system responses prove that the system works significantly irrespective of wind speed values and demanded load.

The direct-drive permanent-magnet synchronous generator (PMSG) with full power converter can achieve wind maximum power point tracking (MPPT) in wide range variation of wind-speed. In this paper an operating characteristic of PMSG is investigated, a MPPT strategy based on hill climbing method for PMSG are present. Simulation and experimental results show that the controllers can extract maximum wind power in good dynamic performance.

Wind generators have attracted a lot of attention in the realm of renewable energy systems, but they are vulnerable to harsh environmental conditions and grid faults. The influence of the manta ray foraging optimizer (MRFO) on the dynamic performance of the two commonly used variable speed wind generators (VSWGs), called the permanent magnet synchronous generator (PMSG) and doubly-fed induction generator (DFIG), is investigated in this research article. The PMSG and DFIG were exposed to identical wind speed changes depending on their wind turbine characteristics, as well as a dangerous three-phase fault, to evaluate the durability of MRFO-based wind side controllers. To protect VSWGs from hazardous gusts and obtain the optimum power from incoming wind speeds, we utilized a pitch angle controller and optimal torque controller, respectively, in our study. During faults, the commonly utilized industrial approach (crowbar system) was exclusively employed to aid the studied VSWGs in achieving fault ride-through (FRT) capability and control of the DC link voltage. Furthermore, an MRFO-based PI controller was used to develop a crowbar system. The modeling of PMSG, DFIG, and MRFO was performed using the MATLAB/Simulink toolbox. We compared performances of PMSG and DFIG in reference tracking and resilience against changes in system parameters under regular and irregular circumstances. The effectiveness and reliability of the optimized controllers in mitigating the adverse impacts of faults and wind gusts were demonstrated by the simulation results. Without considering the exterior circuit of VSWGs or modifying the original architecture, MRFO-PI controllers in the presence of a crowbar system may help cost-effectively alleviate FRT concerns for both studied VSWGs.

Super-twisting sliding mode control of grid-side inverters for wind power generation systems with parameter perturbation