Investigation of aerodynamic interaction between the balloon and the ducted wind turbine in airborne configuration

An aerodynamic analysis is presented in the current work, which estimates the separation distance between the balloon and the turbine in an airborne wind energy system (AWES). The stability of the structure of AWES depends on the aerodynamic interaction between the turbine and the balloon. A minimum gap must be maintained between the balloon and the wind turbine to reduce the interaction between the balloon and the turbine assembly. Three cases of AWES have been studied with a separation gap of 5 m, 10 m, and 16 m to estimate the minimum distance of separation between the balloon and the turbine. The aerodynamic interaction details suggest that a minimum distance of 13 m needs to be maintained between the turbine and the balloon to avoid the interaction between the balloon and turbine. Steady-state simulations of the rotor are run for various wind conditions to evaluate the efficiency of the duct-mounted configuration. The ducted turbine configuration saw a 7.4% increase in torque than the inducted turbine for a wind speed of 5 m s−1. A torque increase of 17.85% was observed when the separation distance was increased to 16 m from earlier 10 m.

Comparative Analysis of Various Types of Control Techniques for Wind Energy Conversion System

The interest towards renewable energy has been enhanced due to zero pollutant emission. Considering the present scenario, wind as a renewable source of energy is highly recommended. As it is freely available and free from pollution, wind can effectively play a role for energy generation. This can produce quality power during grid integrations as the load demands. Due to rapid variations in wind speed, wind energy systems need highly synchronized and powerful controller techniques for power regulations to overcome transients, voltage sags, and swells. A suitable and responsive controller is essential for power generation from wind energy. The controllers for wind energy system are categorized into five controller designs according to their locations to control the demand of the turbine system during grid integrations. In this chapter, various controller designs and implementations are highlighted with reference to previous works and existing studies.

FPGA in the Loop Implementation for Observer Sliding Mode Control of DFIG-Generators for Wind Turbines

This paper presents a new contribution of the nonlinear control technique of electrical energy in a wind energy system. The nonlinear sliding mode technique used to control the powers of the DFIG-Generator is connected to the power grid by two converters (grid side and machine side). The proposed model is validated using tracking and robustness tests with a real wind speed. The control was developed under Matlab/Simulink, and the FPGA in the Loop technique was used to design the DFIG model. By employing a co-simulation, the purpose is to test the controller for the FPGA simulated model or system in its entirety. The results obtained by the cο-simulation show the efficiency of the proposed model in terms of speed and robustness with a rate THD = 0.95, and the proposed model of the sliding mode controller shows a significant improvement in the quality of energy produced by the wind system.

Methodology for optimal design and control of wind energy system based on simplifying assumptions

The study presented in this paper concerns the development of a new methodology for design and controlling a wind energy generation chain. This methodology is based on combined Analytical-Finite Element-Experimental method. This type of converter chosen is an AC-DC inverter with IGBTs to improve the robustness of the power chain structure. It offers a reduction of the cost of the power chain and the improvement of the performances of the global studied system, as the control at power factor equal to unity and providing an electromagnetic torque which is added to the useful torque in order to extract the maximal energy. The control algorithms permit to regulate Le charging voltage and current in their rated values considered as optimal battery charging voltage and current. The global model of the power chain is implemented under the Matlab-Sumilink simulation environment for performance and efficiency analysis.

Model of wind energy system with reduced simulation time validated by classical equivalent model developed under Simulink

Models of a wind energy conversion chain using classical Simulink models of a diode bridge exhibit significant simulation time making difficult its combination with large scales optimization approaches. For this purpose and to increase the degree of compatibility of wind turbine models with large scales optimization approaches such as those based on Genetic Algorithms, a wind energy conversion system having an horizontal axis propeller, an axial generator with permanent magnets, recharging a battery energy accumulator through a diode rectifier is modeled by simplified method reducing simulation time. Indeed, a model of the three phase’s diode rectifier making the simulation time considerably reduced compared to the existing model in the Simulink library is developed. This model is validated by comparison with the model using the classic Simulink library. Another objective of this study is the formulation of the useful torque optimization problem having an essential constraint the reduction of the generator phase’s inductance in the goal to reduce the overvoltage in generator phases.

Cascade Control of the Ground Station Module of an Airborne Wind Energy System

An airborne wind energy system (AWES) can harvest stronger wind streams at higher altitudes which are not accessible to conventional wind turbines. The operation of AWES requires a controller for the tethered aircraft/kite module (KM), as well as a controller for the ground station module (GSM). The literature regarding the control of AWES mostly focuses on the trajectory tracking of the KM. However, an advanced control of the GSM is also key to the successful operation of an AWES. In this paper we propose a cascaded control strategy for the GSM of an AWES during the traction or power generation phase. The GSM comprises a winch and a three-phase induction machine (IM), which acts as a generator. In the outer control-loop, an integral sliding mode control (SMC) algorithm is designed to keep the winch velocity at the prescribed level. A detailed stability analysis is also presented for the existence of the SMC for the perturbed winch system. The rotor flux-based field oriented control (RFOC) of the IM constitutes the inner control-loop. Due to the sophisticated RFOC, the decoupled and instantaneous control of torque and rotor flux is made possible using decentralized proportional integral (PI) controllers. The unknown states required to design RFOC are estimated using a discrete time Kalman filter (DKF), which is based on the quasi-linear model of the IM. The designed GSM controller is integrated with an already developed KM, and the AWES is simulated using MATLAB and Simulink. The simulation study shows that the GSM control system exhibits appropriate performance even in the presence of the wind gusts, which account for the external disturbance.