Power conversion system for low power high altitude wind power generating system

High altitude wind power (HAWP) generating system poses several benefits over conventional wind power (CWP) generating system. An air-borne electric generator is held at high altitude above the ground surface with buoyancy provided by light gas filled blimp/aerostat. In order to minimize the size of the blimp and to reduce the number of electric components in the air-borne system, generation of electrical power is carried out at three phase medium voltage AC (MV-AC) and transmitted to the ground station (without any power conversion) using electromechanical tethers. Thus, transmitted power is interfaced into the distribution level grid at 415 V and 50 Hz. This paper evaluates possible power electronic converter (PEC) topologies that can be used to convert variable voltage and variable frequency three phase medium voltage AC power into constant frequency distribution level grid voltage. Three different PEC topologies are proposed that allow generation and grid side current control and generation side maximum power point tracking (MPPT) control. In addition, the proposed PECs provide step down of voltage and electrical isolation with the distribution grid. Suitable active and passive components are selected for 100 kW HAWP system and overall semiconductor losses are evaluated. The converters are simulated using computer software programs PSIM-9 and MATLAB. The converter that exhibits good efficiency, easy control of generation and grid side current as well as facilitates MPPT control of HAWP generation side is selected for grid interface of isolated HAWP system.

This paper discusses the design of a low tip-speed ratio, drag type vertical axis wind turbine which is incorporated with permanent magnet synchronous generator with maximum power point tracking (MPPT) strategy of control system to acquire the optimal performance. By using two dimensional large eddy simulations (LES) method as fluid dynamic model, the calculated power coefficient for this multi-blade vertical axis wind turbine may reach 0.34 at tip speed ratio (TSR) ranging from 0.8 to 1.0. Also, with the aids of simulation results, a direct coupled permanent magnet synchronous generator with 64-poles is designed and fabricated to generate 1.5 kW rated power at 90 rpm in 12 m/s wind speed. By changing the shape of magnet and applying approximate-skew method as stepped magnet configuration, the cogging torque and noise level of generator can be minimized. Moreover, MPPT control system with low current harmonic distortion level is designed to transfer energy into power grid with estimated 92% of power efficiency. Consequently, by eliminating gearbox system, low start-up wind speed, low current harmonic distortion and low cogging torque, the proposed of low acoustic/noise level wind turbine generator system can be applied for urban-environmental usage.

The MPPT (Maximum Power Point Tracking) control topology based on Fuzzy logic, and analysis of the Vienna Rectifier for the small-scale Wind Turbine System (WTS) is proposed in this paper. The PMSG (Permanent Magnet Synchronous Generator) of the WTS generates the output power that is fluctuated due to irregular wind velocity, which has to be controlled for the smooth output power. Many controlstrategies are projected by the researchers for the settled power output, but the conventional control techniques getting more complex. One of the simple and robust methods that enable for the MPPT is fuzzy logic control. The above mechanism regulates the speed of PMSG and the DC power output. Moreover, it is engaged in the parameter optimization and the speed control of the PMSG. A fuzzy logic MPPT controller based Vienna Rectifier is used in this paper for a 1kW WTS with improved efficiency and reduced harmonics, and the results are justified using MATLAB/Simulink.

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.

Recurrent modified Elman neural network control of PM synchronous generator system using wind turbine emulator of PM synchronous servo motor drive

A Novel Maximum Power Tracking by VSAS approach for Permanent Magnet Direct Drive WECS

—This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under unbalanced grid fault conditions are investigated. Three control targets for the grid-side converter during network unbalance conditions are identified, including eliminating the oscillations in the total active power or reactive power or no negative-sequence current injecting into the grid. Meanwhile, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy storage unit under unbalanced grid fault.

The direct-drive Permanent Magnet Synchronous Generator (PMSG) wind power imitation platform is an essential requirement for its research, development and product test. It's more efficient and flexible to demonstrate control strategies including the wind turbine's Maximum Power Point Tracking (MPPT). Conventionally, many control strategies of the motor's speed or torque are used to implement the turbine MPPT imitation, which, however, much depend on the motor parameters and are only for the Double Feed Induction Generator (DFIG) system, but rarely for direct-drive PMSG one. Thus, a novel control strategy for the wind turbine MPPT implementation is proposed, which provides a direct power control method of DC motor together with decoupled vector control of PMSG without the speed sensor. Using this control strategy, the system less depends on either parameters of the DC motor or the PMSG, and has excellent dynamic performance and high steady-state precision. The analysis, simulation and experimental results have verified its feasibility and validity.

The paper proposes an adaptive sliding observer to accurately estimate the rotor position for a direct-drive permanent magnet synchronous generator (PMSG). Without any position sensor, the generator torque and flux responses retain high performance both in the steady state and during transients. The problem on the shaft encoder installation difficulty, reliability and disturbance in encoder cable is remedied and the reliability of the PMSG generating system is increased. The grid voltage orientation control is implemented into the grid converter in which nearly sinusoidal input current and fast dc link voltage regulation can be achieved. Experimental results verify the effectiveness of the proposed observer for PMSG and high performance power production can be obtained.

This paper proposes a Direct Torque Control (DTC) method for Wind Power System (WPS) based Permanent Magnet Synchronous Generator (PMSG) and Backstepping approach. In this work, generator side and grid-side converter with filter are used as the interface between the wind turbine and grid. Backstepping approach demonstrates great performance in complicated nonlinear systems control such as WPS. So, the control method combines the DTC to achieve Maximum Power Point Tracking (MPPT) and Backstepping approach to sustain the DC-bus voltage and to regulate the grid-side power factor. In addition, control strategy is developed in the sense of Lyapunov stability theorem for the WPS. Simulation results using MATLAB/Simulink validate the effectiveness of the proposed controllers.

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.

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.

This paper proposes a dynamic maximum power point tracking (MPPT) controller for a permanent magnet synchronous generator (PMSG)-based variable speed autonomous wind power conversion system (WPCS) with an energy storage system (ESS). The dynamic controller extracts the maximum power from the WPCS under variable speed conditions using a cascade neural network (CNN)-based MPPT algorithm. Also, the efficient power management between an ESS, load and WPCS is obtained using a conventional PI controller. The CNN is trained and tested using simulation and experimental data, respectively. The performance of CNN-based MPPT is also compared with feed-forward-based MPPT in terms of accuracy and complexity. This paper also discusses FPGA implementation aspects of CNN-based MPPT and hardware resources management for desired accuracy. The proposed method is first implemented on a simulation model 900-watt PMSG-based WECS and results are validated. Further, the enthusiastic results were finally evaluated in a hardware setup of 1 HP PMSG-based WECS. The proposed method is shown to extract maximum power with a simple structure and provide a better response to variable wind speed.

Conventional wind energy conversion systems (WECS) typically employ rotor side synchronous frame current control strategies to regulate the active/reactive power supplied by the WECS generator. Such strategies require accurate information regarding the rotor position and speed in order to set the dq frame reference currents and to perform the necessary frame transformations. This information can be obtained using a rotor speed sensor (i.e. a shaft encoder) or via a sensor-less strategy in which a dynamic machine model and stator current measurements are used to estimate the true rotor position. This paper now presents an alternative approach to control the active/reactive power supplied by the WECS permanent magnet synchronous generator (PMSG). The proposed strategy uses the three phase converter modulation commands to identify the phase and frequency of the PMSG stator terminal voltages. This enables the direct regulation of the real and reactive power extracted at the PMSG terminal voltages using a stationary frame Proportional + Resonant (PR) stator current regulation strategy, without requiring precise knowledge of the rotor position. Maximum power point tracking (MPPT) functions are realized using the measured PMSG terminal voltage frequency to form an estimate of the rotor speed. The result is a simple robust WECS control strategy that rapidly and accurately tracks rotor speed changes caused by wind speed variations. Detailed simulation and experimental results obtained for a scaled laboratory prototype system are presented to validate the proposed strategy.

This chapter deals with a comprehensive overview study of the direct‐driven (DD) permanent magnet synchronous generator (PMSG) for wind‐energy generation system for stand‐alone applications. The dynamic model of PMSG is presented, and different maximum power point tracking (MPPT) algorithms have been realized in the aim to compare their performance. A comparison of performances of the conventional P&O MPPT and the fuzzy logic P&O (FLC P&O) MPPT is presented. Control technique for the presented system is presented and analyzed for the generator side converter. The simulation results carried out using Matlab/Simulink software show the effectiveness of the wind turbine control system.