nan Kamal-Al-Haddad

Battery Based Voltage and Frequency Controller for Parallel Operated Isolated Asynchronous Generators

This paper deals with a battery energy storage system (BESS) based voltage and frequency (VF) controller for parallel operated isolated asynchronous generators (IAGs) driven by uncontrolled pico hydro turbines used in constant power applications. The individual AC capacitor banks are used to generate the rated voltage at no load while additional demand of reactive power for the load and generators is met by the controller. The proposed controller is having capability of harmonic elimination, load balancing and load leveling along with voltage and frequency control. The proposed controller is realized using an IGBT (insulated gate bipolar transistor) based voltage source converter (VSC) and battery system at its DC link. Since the VSC allows bidirectional flow of active and reactive power; thus it regulates the voltage and frequency. The effectiveness of the proposed controller is demonstrated through the MATLAB based simulations using Simulink and PSB (power system block set) toolboxes and different aspects of the controller are studied for parallel operated isolated asynchronous generators.

“SRF theory revisited” to control self supported dynamic voltage restorer (DVR) for unbalanced and nonlinear loads

The protection of the sensitive unbalanced nonlinear loads from sag/swell, distortion, and unbalance in supply voltage is achieved economically using the dynamic voltage restorer (DVR). A simple generalized algorithm based on basic synchronous-reference-frame theory has been developed for the generation of instantaneous reference compensating voltages for controlling a DVR. This novel algorithm makes use of the fundamental positive-sequence phase voltages extracted by sensing only two unbalanced and/or distorted line voltages. The algorithm is general enough to handle linear as well as nonlinear loads. The compensating voltages when injected in series with a distribution feeder by three single-phase H-bridge voltage-source converters with a constant switching frequency hysteresis band voltage controller tightly regulate the voltage at the load terminals against any power quality problems on the source side. A capacitor-supported DVR does not need any active power during steady-state operation because the injected voltage is in quadrature with the feeder current. The proposed control strategy is validated through extensive simulation and real-time experimental studies.

Improved Power Quality Based Controller for a 3-Phase 4-Wire Isolated Wind Energy System

This paper deals with the regulation of voltage and frequency of an isolated wind energy conversion system (IWECS) based on a capacitor excited asynchronous generator and feeding 3-phase 4-wire loads. The proposed controller consists of an IGBT (Insulted Gate Bipolar Junction Transistor) based 4-leg voltage source converter (VSC) and a battery at its DC link. A bank of excitation capacitor with neutral and fourth leg of the proposed controller provides the neutral terminal for the loads. The complete electromechanical system is modeled and simulated in MATLAB using Simulink and PSB (Power System Blockset) toolboxes. The simulated results are presented to demonstrate the capability of the proposed controller as a voltage and frequency regulator, a harmonic eliminator, a load balancer, and a neutral current compensator for different electrical (consumer loads variation) and mechanical (wind speed variation) dynamic conditions in an isolated wind energy conversion system.

Indirect control of capacitor supported DVR for power quality improvement in distribution system

The dynamic voltage restorer (DVR) is used to regulate the voltage at the load terminals from various power quality problems like sag, swell, harmonics, unbalance etc., in supply voltage. In this paper, a novel control strategy is proposed to control a capacitor supported DVR for sag, swell, harmonics and unbalance in supply voltage. The reference signal for the series connected DVR is obtained indirectly from the extracted load terminal reference voltage. The proposed DVR control strategy is validated through extensive computer simulation studies using MATLAB software with its Simulink and power system block set.

A Solid State Compensator with Energy Storage for Isolated Diesel Generator Set

This paper presents the control of battery energy storage system (BESS) with diesel generator (DG) set. The performance of the DG set is observed best when operated at full load or near full load (up to 80-100% load) condition. For this purpose a BESS is employed which ensures the load on the generator remains in between 80% to 100% of full load. Under light load condition (load less than 80%) the battery is being charged and in heavy load condition (load more than 100%) energy from battery is utilized to feed extra power to the load and when load is in-between 80 to 100% battery remain in floating condition. Along with load management, BESS provides the reactive power, harmonic current and unbalanced load current compensation. The control of BESS is achieved using synchronous reference frame theory (SRF) to extract the balance positive sequence real fundamental frequency component of load current. The switching of voltage source converter (VSC) working as BESS is achieved by forcing source currents to follow reference currents using hysteresis based PWM controller. The complete system is simulated under MATLAB environment using SIMULINK and PSB block-sets to demonstrate the capabilities of the system

Analysis and design of isolated solar-PV energy generating system

This paper deals with the design, control and modeling of an isolated solar-PV (Photo-Voltaic) energy generating system. The proposed system is designed for supplying an average consumer load of 1.5 kW. A constant voltage method is applied to the PV array for MPPT (Maximum Power Point Tracking). A push-pull boost dc-dc converter is fed from the PV array for charging the battery. A VSI (Voltage Source Inverter) utilizing multi-loop feedback control technique with a BESS (Battery Energy Storage System) is used for power management of the proposed system. This solar-PV energy generating system is designed, modeled and its performance is simulated in the Matlab using the Simulink, Sim power system etc. toolboxes. Simulated results are presented for the linear, nonlinear and motor loads to demonstrate its performance.

Capacitor Excited Asynchronous Generator for an Isolated Wind Energy Conversion System

This paper deals with the control of voltage and frequency of an isolated wind energy conversion system (WECS) based on capacitor excited asynchronous generator and feeding 3-phase 4-wire loads. The proposed controller consists of an IGBT (insulated gate bipolar junction transistor) based 4-leg voltage source converter (VSC) and a battery at DC link. Three legs of the converter are connected to each phase of the generator while fourth leg along-with neutral terminal of the capacitor creates the neutral terminal for the load. The proposed controller is having bidirectional flow capability of active and reactive powers by which it controls the system voltage and frequency with variation of consumer loads and the speed of the wind. The complete electromechanical system is modeled and simulated in MATLAB using Simulink and PSB (Power System Blockset) toolboxes. The simulated results are presented to demonstrate the capability of the proposed controller as a voltage and frequency regulator, harmonic eliminator, load balancer, and a neutral current compensator for different electrical (varying consumer loads) and mechanical (varying wind speed) dynamic conditions in an isolated wind energy conversion system.

Improved power quality opto-couplerless Cuk converter for flickerless LED lighting

This paper presents a single stage isolated Cuk converter for low power light emitting diode (LED) driver systems. An opto-couplerless feedback control using primary-side regulation technology is presented in discontinuous conduction mode (DCM). A complete analysis of the converter is carried out using pulse-frequency modulation technique. The primary focus of this work is to develop a cost effective solution for an LED driver with improved power quality and efficiency. For low power lighting, this work results in a maximum power factor (PF) of 0.99 and minimum total harmonic distortion (THD) in AC mains current of 3.37% over universal AC voltage. The proposed Cuk topology offers high efficiency and constant voltage-constant current (CV-CC) control. Moreover, for high efficiency, coupling capacitors at both sides of the transformer have been optimized to a film capacitor with low dissipation factor and long life as compared to commonly used electrolytic capacitors. A 27 W prototype with a converter efficiency of 88% has been developed to validate the proposed approach.

An independent active and reactive power control of an isolated asynchronous generator in 3-phase 4-wire applications

This paper deals with an investigation on a controller, which regulates the voltage and frequency of an isolated asynchronous generator (IAG) driven by an uncontrolled pico hydro turbine to feed 3-phase 4-wire loads. The proposed controller is having capability to regulate the voltage and frequency in decoupled manner. A STATCOM (static synchronous compensator) is used to control the reactive power to regulate the voltage, while frequency regulation is achieved by active power control through an electronic load controller (ELC). The voltage regulator (VR) consists of an IGBT (insulated gate bipolar junction transistor) based three single-phase voltage source converters (VSCs), which are connected to each phase of the generator through three single-phase transformers. An advantage of this three-phase four wire topology is that DC link voltage can be maintained at optimum level. Frequency regulator (FR) consists of a diode bridge rectifier with a chopper switch and an auxiliary load. The proposed controller with an IAG system is modeled and simulated in MATLAB using power system block set (PSB) and Simulink toolboxes. Simulated results have demonstrated that proposed voltage and frequency controller for an IAG driven by uncontrolled pico hydro turbine offers the functioning as a harmonic eliminator, a load balancer and a neutral current compensator.

A novel ambiance changing energy saving LED lighting system with PFM operated Zeta converter

This study deals the design, simulation and implementation of an isolated Zeta converter based novel cost-effective, dual-colored, step-dimming with power quality improvement at universal AC mains while operating the power factor correction (PFC) converter in Discontinuous Conduction Mode (DCM). The PFC Zeta converter is able to provide regulated output current to a string of LED load of 23 W and maintains the power quality indices within the requirements of IEC61000-3-2 for class C equipments with high level of efficiency. Moreover, to achieve cost benefit and size reduction, this converter utilizes reduced control circuitry for the emerging LED lighting solutions. A novel cost effective color changing is discussed with primary-side regulation (PSR) technique using an isolated Zeta converter. A prototype of the Zeta converter with color changing solution and step-dimming mechanism is implemented to evaluate the proposed approach. The overall power factor at full load condition is achieved around 0.98 and AC mains current THD as 7.15% with an efficiency of 85.56% at rated voltage of 220V.