Emre Ozsoy

A stator voltage oriented doubly fed induction generator control method with a disturbance observer

Due to their robustness and cost effectiveness, double fed induction generator (DFIG) based wind turbines are becoming very popular in wind energy conversion systems. Robustness of any implemented control structure can easily be lost due to nonlinearities, variations in the DFIG parameters and network voltage failures. In this study, machine parameter dependent terms will be estimated with the first order low pass filter disturbance observer, and stator voltage orientation will be applied in the experimental test bed. DSP ACE DS1103 platform is used as a digital controller.

Design of a robust cascaded controller for Cuk converter

In this paper, design of a robust cascade controller for a Cuk converter is investigated. The controller contains two loop cascaded structure. The external voltage loop, which is the slow loop, contains the continuous proportionalintegral( PI) voltage controller whereas the internal current loop, which is the fast loop, contains the continuous sliding mode controller(CSMC). The controller effectiveness is validated by simulating the Cuk converter in SimPowerSystems ® toolbox of MATLAB/Simulink ®. The simulation is done for six different cases including ideal case, sudden variation of input supply voltage, load resistance, reference voltage, for noise disturbance and parametric variation. It is shown that the performance of the proposed controller is satisfactory and the ultimate goal of tracking the reference by the converter output voltage and the inductor current is achieved with little or no sensitivity to the uncertainties simulated.

Design and analysis of robust rotor current controller for doubly fed induction generator

In the past decade wind energy systems were developed for efficient energy conversion. Most of the variable speed wind turbine systems include doubly fed induction generator (DFIG). DFIGs are used in electrical grid connected and standalone systems. This paper presents a novel, robust, rotor current controller structure for both grid connected and stand-alone DFIG applications. Controller is designed for the robustness against change in machine parameters, generator speed changes and load changes in stand alone systems. In the heart of controller design lays low pass filter based disturbance observer. Experimental results are provided that verify controller performance in grid connected scenario and stand alone generator scenario (local grid). Experiments are done using 1.1KW DFIG experimental test bed and custom developed switching inverter.

Performance comparison of static and dynamic state estimators for electric distribution systems

Abstract State estimation is an integral component of energy management systems used for the monitoring and control of operation of transmission networks worldwide. However, it has so far not yet been widely adopted in the distribution networks due to their passive nature with no active generation. But this scenario is challenged by the integration of distributed generators (DGs) at this level. Various static and dynamic state estimators have been researched for the transmission systems. These cannot be directly applied to the distribution systems due to their different philosophy of operation. Thus the performance of these estimators need to be re-evaluated for the distribution systems. This paper presents a computational and statistical performance of famous static estimator such as weighted least squares (WLS) and dynamic state estimators such as extended Kalman filter (EKF) and unscented Kalman filter (UKF) for electric distribution system. Additionally, an improved-UKF (IUKF) is also proposed which enhances the robustness and numerical stability of the existing UKF algorithm. All the estimators are tested for load variation and bad data for IEEE-30, 33 and 69 bus radial distribution networks using statistical performance metrics such as Maximum Absolute Deviation (MAD), Maximum Absolute Percent Error (MAPE), Root Mean Square Error (RMSE) and Overall Performance index (J). Based on these metrics, IUKF outperforms other estimators under the simulated noisy measurement conditions.

DSC-based implementation for power control of DFIG in microgrid applications

This paper presents a compact and low cost digital signal controller (DSC) based implementation for power control of a doubly fed induction generator (DFIG) based wind energy setup for micro-grid applications. The experimental setup consists of a back to back converter, a 1.1 kW DFIG and two low cost, industry standard DSCs. Stator active power and reactive power are controlled by means of the rotor currents. Decoupled components of the rotor current in a rotating frame are controlled by a robust, disturbance observer based control structure. The proposed controller was validated through experiments.