A. M. O. Haruni

A Novel Operation and Control Strategy for a Standalone Hybrid Renewable Power System

This paper proposes a novel operation and control strategy for a renewable hybrid power system for a standalone operation. The proposed hybrid system consists of a wind turbine, a fuel cell, an electrolyzer, a battery storage unit, and a set of loads. The overall control strategy is based on a two-level structure. The top level is the energy management and power regulation system. Depending on wind and load conditions, this system generates reference dynamic operating points to low level individual subsystems. The energy management and power regulation system also controls the load scheduling operation during unfavorable wind conditions under inadequate energy storage in order to avoid a system blackout. Based on the reference dynamic operating points of the individual subsystems, the local controllers control the wind turbine, fuel cell, electrolyzer, and battery storage units. The proposed control system is implemented in MATLAB Simpower software and tested for various wind and load conditions. Results are presented and discussed.

Dynamic operation and control of a hybrid wind-diesel stand alone power systems

This paper presents the dynamic operation and control strategies of a hybrid wind-diesel-battery energy storage based power supply system for isolated communities are investigated. Control strategies for voltage and frequency stabilization and efficient power flow among the hybrid system components are developed. The voltage and frequency of the hybrid wind-diesel system is controlled either by a load side inverter or by diesel generation depending on the wind conditions. During high penetration of wind, the wind turbine supplies the required power to the load. A battery energy storage system is connected to the dc-link to balance the power generated from the wind turbine and the power demand by load. Under low wind conditions, a diesel generator is used with wind energy conversion system to generate the required power to the load. A power sharing technique is developed to allocate power generation for diesel generator in low wind conditions. Results show that the control strategies work very well under dynamic and steady state condition to supply power to the load.

Analysis of harmonics and voltage fluctuation using different models of Arc furnace

In recent years, the rapid growth of nonlinear loads, such as power electronic control equipment and arc furnace, is creating harmonics and voltage distortion problems in power networks. In this paper we will present a comparative study of different arc furnace models for harmonics and voltage distortion analysis. Six different models of arc furnace represented in time domain and frequency domain are used for the analysis. Analysis of harmonics of arc voltage and current and voltage distortion has been conducted by different arc furnace models. Arc furnace models are implemented in MATLAB and tested on a prototype system. The results have demonstrated that the accuracy of different arc furnace models is different for analysis of harmonics and voltage fluctuation.

Control of a direct drive IPM synchronous generator based variable speed wind turbine with energy storage

This paper presents a novel control strategy for a direct drive interior permanent magnet (IPM) synchronous generator based variable speed wind turbine with controlled energy storage. The overall control system consists of a machine side converter controller, a bi-directional dc-dc converter controller for battery energy storage management and load side inverter controller for voltage and frequency regulation. The machine side controller controls the generator speed in order to extract optimum power from the fluctuating wind. The machine side controller is also responsible to achieve maximum efficiency operation of the generator by regulating the d- and q- axis components of stator current. A bi-directional dc to dc battery controller is utilized to balance power generation from the wind and load requirements during wind fluctuations. The load side inverter controller regulates the output voltage and frequency under varying wind and load conditions. The extensive simulation results confirm the effectiveness of the proposed controllers for the wind-battery energy storage based standalone power generation system.

Control strategy of a stand-alone variable speed wind turbine with integrated energy storage system using NPC converter

This paper presents a control strategy for a standalone power system comprising of a wind turbine and battery storage systems. The proposed control system consists of a back-to-back NPC converter controller and a bi-directional battery storage converter controller. The back-to-back three-level converter consisting of a machine-side converter and a load side inverter is used to fulfill several objectives. Firstly, the machine-side converter controller is used to extract the maximum power from the variable wind. Secondly, the machine-side converter controller ensures the maximum efficient operation of the interior type permanent magnet synchronous generator. Thirdly, the load-side inverter controller regulates the output voltage and frequency under wind and load variations. A bi-directional dc-to-dc converter is used to control the power flow of the battery storage system under different wind and load conditions. The proposed control system is implemented in MATLAB environment and simulation studies have been conducted for various wind and load conditions.

A novel power management control strategy for a renewable stand-alone power system

This paper proposes an overall power management control strategy of a stand-alone power supply system consisting of wind turbine and battery storage system. The overall control strategy consists of two layer structure. The upper layer is overall power management controller that generates the reference signal for the local controller. Based on reference signal, the local controllers control the wind energy conversion system and energy storage system. The wind energy conversion system is controlled in order to achieve optimum power from the changing wind. The energy storage system is controlled by a bi-directional dc-dc controller. The performance of the controller is verified in a simulated wind and load conditions and results are presented.

Smooth Synchronisation and Power Sharing Schemes for High Penetration Wind Diesel Hybrid Remote Area Power Systems

Abstract The paper proposes synchronisation and power sharing schemes for fast connection and smooth operation of high penetration wind-diesel hybrid systems. The synchronisation is realised by controlling the power electronic interface of the wind energy systems rather than the classical diesel engine synchronisation scheme. The power sharing between the diesel and wind systems is achieved by a modified power-frequency droop control method. The proposed schemes are tested on a simulated hybrid system to demonstrate their effectiveness.

Hybrid stand-alone power systems with hydrogen energy storage for isolated communities

This paper presents a structured approach to infrastructure development for the operation of remote area power systems with wind-hydrogen renewable generation solutions. When the level of power produced by a wind turbine is higher than the load-demand during the peak-hours, the excess power is utilized to produce hydrogen. When power produced by a wind turbine is lower than the demand, the diesel generator with a hydrogen-diesel duel fuel system is used to satisfy the demand. A major emphasis of the paper is to present the performance of the developed control systems of the wind energy system and the diesel system in different operating modes.

An Artificial Intelligence Approach to Develop a Time-Series Prediction Model of The Arc Furnace Resistance

The control scheme of an arc furnace electrode positioning system aims to deliver an optimum stable reaction zone below the electrodes by maintaining a fixpoint resistance. However, because of random movement of melted materials during melting period, the resistance of the arc furnace changes randomly. As a result, the electrodes have to move accordingly to obtain a fix-point resistance. Moreover, it is often found that the arc furnace resistance changes very fast and it is impossible for the electrode to track the random change of resistance. Consequently, the furnace becomes unstable and it is often impossible to achieve required production per unit power. Hence, the control system often relies on prediction tools. However, it is difficult to predict the arc furnace resistance using conventional mathematical models. As a result, in this paper, Adaptive Neuro-Fuzzy Inference System (ANFIS) is used to capture the random and time-varying nature of arc furnace resistance. The performance of the proposed model is evaluated by presenting a case study where the outputs of the proposed model are compared with the data recorded from an actual metallurgical plant.

Voltage and power management in a microgrid system with diesel generator and energy storage

This paper presents results of the development of a voltage and power management system for a microgrid. The microgrid under study is a power system located on the island with a peak load of 1.8 MW connected to the main power grid via two submarine cables. Due to a long radial network configuration with a high ratio of resistance to reactance, the system experiences low voltages problems at remote locations. In addition, during peak load conditions, thermal ratings of the submarine cables can be violated. Integration of the local diesel generator and energy storage system is proposed to overcome existing problems. The proposed voltage and power management scheme coordinates the on-load tap-changing (OLTC) transformer, diesel generator and energy storage system of the microgrid. The scheme ensures that the voltage profile of the microgrid is maintained within Electricity Code under peak conditions. Results of the study are presented and discussed.