Continuous biodiesel process using ultrasonic in-line reactor for Jatropha Curcas Oil (JCO)

Biodiesel is an alternative fuel for replacing diesel fuel in compression ignition engines. Due to the complexity of the diesel fuel production and exhaust emissions from petroleum-fuelled engines will give negative impact to the environment. In this study, the sodium hydroxide as the catalyst was used to react with methanol for obtaining chemical compound that is called methyl ester which is known as biodiesel. The method used are Ultrasonic. Basically, this method will reduce the reaction time on the conversation of jatropha curcas oil (JCO) into biodiesel. The experiment was to determine the effect of esters contents by reaction time, molar ratio methanol (MeOH) to JCO, the amount of catalyst, frequency and power output of ultrasonic using ultrasonic in-line reactor. The optimum production of biodiesel was achieved at 7 minutes of reaction time, 1%wt of catalyst concentration and molar ratio methanol to oil 12:1, frequency ultrasonic of 20 KHz and ultrasonic output 600 Watt at temperature 65°C. The biodiesel produced by this method has been referred according to ASTM D6751. From the result, the biodiesel produced from this method has satisfied the requirement biodiesel standard. This optimum result in this research can be used to run larger pilot plant designed for industry

Contributions to cascade linear control strategies applied to grid-connected Voltage-Source Converters

El trabajo desarrollado en esta Tesis se centra en optimizar el comportamiento de Voltage-Source Converters (VSCs) cuando son utilizados como interfaz con la red eléctrica, tanto para absorber como para entregar energía de la red con la mejor calidad posible y cumpliendo con los estándares. Para tal fin, esta Tesis se centra en el control de sistemas lineales conectados en cascada aplicados al control de VSCs conectados en paralelo con la red eléctrica a través de un filtro L, especialmente en conexiones con redes débiles y en dos líneas de trabajo: (i) seguimiento de armónicos de las corrientes de red y rechazo de armónicos de las tensiones de red, y (ii) control de la tensión del PCC en caso de desequilibrio. Para ello, esta Tesis realiza contribuciones en el área del control de corriente y control de la tensión del PCC. De entre las técnicas existentes para implementar el control de corriente para compensación armónica, dos de las más utilizadas son el control resonante y el control repetitivo, tanto en ejes de referencia estacionarios como síncronos. Se ha realizado un exhaustivo estudio de diferentes estructuras para implementar tales controles, mostrando su algoritmo adaptativo en frecuencia para cada una de ellas y analizando su carga computacional. Además, se han facilitado directrices básicas para su programación en un DSP. Se ha analizado también el esquema de control de corriente para establecer una comparación entre las diferentes estructuras. Después de estudiar en profundidad el control de corriente de un VSC conectado a la red eléctrica, el segundo control a analizar es el control de tensión del PCC. La presencia de una tensión desequilibrada en el PCC da lugar a la aparición de una componente de corriente de secuencia negativa, que deteriora el comportamiento del sistema de control cuando se emplean las técnicas de control convencionales. Los STATCOMs son bien conocidos por ser una aplicación de potencia capaz de llevar a cabo la regulación de la tensión en el PCC en líneas de distribución que pueden ser susceptibles de sufrir perturbaciones. Esta Tesis propone el uso de un controlador de tensión en ejes de referencia síncronos para compensar una tensión desequilibrada a través de un STATCOM, permitiendo controlar independientemente tanto la secuencia positiva como la secuencia negativa. Además, este controlador incluye aspectos como un mecanismo de antiwindup y droop control para mejorar su comportamiento. Se han realizado varias pruebas experimentales para analizar las características de los controladores de corriente abordados en esta Tesis. Todas ellas han sido realizadas bajo las mismas condiciones de potencia, tensión y corriente, de modo que se pueden extraer resultados comparativos. Estas pruebas pretenden caracterizar la respuesta transitoria, la respuesta en régimen permanente, el comportamiento frente a saltos de frecuencia y la carga computacional de los controladores de corriente estudiados

STATCOM Controller (Design and Assessment) for Transmission and Distribution System Problems

Due to immense increase in needs of human being, the power generation system encounters a deficiency of key energy sources as a result the demand is increasing day by day without an increase in alternative generation resources and transmission line capability. The constantly increase of electrical power        demands and loads, especially non-linear loads making the power system network become more        complicate to operate and the system becomes unstable with large power flows without proper control and operation. The advancement in power system with time have brings new challenges and sometimes it is difficult to operate system in stable condition due to complex    system network. One of the invention of power electronics is FACTS technology. FACTS (Flexible Alternating Current Transmission Systems) devices are based on power electronics and other dynamic controllers that provide control of one or more AC transmission system parameters to upgrade the controllability and to increase power transfer capability. One way to improve the power system control is by applying FACTS controllers such as D-STATCOM (Distribution Static Synchronous Compensator) which can be introduced to the power    system to regulate terminal voltage and to improve power factor of system.A comprehensive D-STATCOM controller is to be established which when will be introduced in the    power system will eliminate the voltage fluctuations and improve power stability. A test power system is    being designed in MATLAB Sim Power System with non-linear load and wind energy source as          renewable source and then the systems is analyzed with and without the D-STATCOM controller and both the result are being compared to check the performance of the designed D-STATCOM Controller. Keywords: Unified Power Flow Controller (UPFC), Distribution Static Compensator (D-STATCOM), Static Synchronous Series Compensator (SSSC

Comprehensive STATCOM Control For Distribution And Transmission System Applications

This thesis presents the development of a comprehensive STATCOM controller for load compensation, voltage regulation and voltage balancing in electric power distribution and transmission networks. The behavior of this controller is first validated with published results. Subsequently, the performance of this STATCOM controller is examined in a realistic Hydro One distribution feeder for accomplishing the compensation of both mildly and grossly unbalanced loads, and balancing of network voltages using PSCAD/EMTDC software. The STATCOM voltage control function is utilized for increasing the connectivity of wind plants in the same distribution feeder. The thesis further presents a frequency scanning technique for simple and rapid identification of the potential of subsynchronous resonance in induction generator based wind farms connected to series compensated lines, utilizing MATLAB software. This technique is validated by published eigenvalue analysis results. The voltage control performance of the developed comprehensive STATCOM controller is then demonstrated for different scenarios in the modified IEEE First SSR Benchmark transmission system for mitigating subsynchronous resonance in series compensated wind farms using industry grade PSCAD/EMTDC software

Simulation of Linear Feedback Control of D-Statcom for Voltage Sag Mitigation

Recently, the demands of electrical supply by industries and domestics customers have increased tremendously. This is due to the increase of large loads which are sensitive in industries like semiconductor and the building of new housing estates. These have caused power quality problems to both end users by the increasing demand of electricity. The major power quality problems that always occur in power systems are voltage sag, unbalanced voltage and unbalanced current. Various circuit topologies and controls have been developed, aimed at mitigating these power quality problems. One of the solutions is by using the Custom Power devices. These Custom Power devices respond to poor power quality problems such as voltage sag, unbalanced voltage and unbalanced current by improve the quality of the system. Custom Power family consists of Distribution Static Compensator (D-STATCOM), Dynamic Voltage Restorer (DVR), Solid State Fault Current Limiter (SSFCL), Active Power Filter (APF), and Solid State Transfer Switch (SSTC) are power electronic based devices. These Custom Power devices will solve power quality problems at the distribution system by injecting voltage or current referring to the amount of reference voltage or current fiom the distribution system. In this thesis, D-STATCOM has been used as a device to solve voltage sags and unbalanced fault conditions. From the studies, the conventional D-STATCOM controller that uses Proportional Integration (PI) controller is capable of solving voltage sag but not capable of solving the unbalanced conditions. This is because the conventional PI controller cannot respond to the negative sequence components. The negative sequence component is induced by unbalanced faults which happen in a system. This negative sequence component will block the Gate Turn Off (GTO) Thyristor fiom firing. From the studies, there are two types of techniques in solving negative sequence components namely negative sequence controller or using DQ transformation of the current. This thesis explains the application of DQ transformation which changes the 3 phase components to direct and quadrate components and the pole placement controller. Both of these techniques have been consider for designing the new type of controller. This new type of controller is capable of giving order to D-STATCOM to inject the current to solve voltage sag and unbalanced conditions. The simulations of the DSTATCOM and the pole placement controller were implemented in Mathematical Laboratory (MATLAB) program version 6.5 developed by MATHWORKS Inc. The D-STATCOM has been connected to the 1 lkV distribution system in shunt with fault components. The results obtained from the simulations clearly showed that the designed D-STATCOM with the new pole placement controller is capable of mitigating voltage sag and unbalanced fault conditions. The developed simulation model will be useful for future power quality studies in distribution systems

Mitigation of Power Quality Problems Using Custom Power Devices: A Review

Electrical power quality (EPQ) in distribution systems is a critical issue for commercial, industrial and residential applications. The new concept of advanced power electronic based Custom Power Devices (CPDs) mainly distributed static synchronous compensator (D-STATCOM), dynamic voltage restorer (DVR) and unified power quality conditioner (UPQC) have been developed due to lacking the performance of traditional compensating devices to minimize power quality disturbances. This paper presents a comprehensive review on D-STATCOM, DVR and UPQC to solve the electrical power quality problems of the distribution networks. This is intended to present a broad overview of the various possible DSTATCOM, DVR and UPQC configurations for single-phase (two wire) and three-phase (three-wire and four-wire) networks and control strategies for the compensation of various power quality disturbances. Apart from this, comprehensive explanation, comparison, and discussion on D-STATCOM, DVR, and UPQC are presented. This paper is aimed to explore a broad prospective on the status of D-STATCOMs, DVRs, and UPQCs to researchers, engineers and the community dealing with the power quality enhancement. A classified list of some latest research publications on the topic is also appended for a quick reference

Control System Design, Analysis, and Simulation of a Photovoltaic Inverter for Unbalanced Load Compensation in a Microgrid

This thesis presents a control scheme for a single-stage three-phase Photovoltaic (PV) converter with negative sequence load current compensation. In this thesis a dual virtual impedance active damping technique for an LCL filter is proposed to address the issue of LCL filter resonance. Both inverter-side current and the capacitor current are used in the feedback loop. Using both signals provides higher DC rejection than using capacitor current alone. The proposed active damping scheme results in a faster transient response and higher damping ratio than can be obtained using inverter-side current alone. The feedback gains can be calculated to achieve a specified damping level. A method of determining the gains of the Proportional and Resonant current controller based on frequency response characteristics is presented. For a specified set of gain and phase margins, the controller gains can be calculated explicitly. Furthermore, a modification is proposed to prevent windup in the resonator. A numerically compensated Half-Cycle Discrete Fourier Transform (HCDFT) method is developed to calculate the negative sequence component of the load current. The numerical compensation allows the HCDFT to accurately estimate the fundamental component of the load current under off-nominal frequency conditions. The proposed HCDFT method is shown to have a quick settling time that is comparable to that obtained with conventional sequence compensation techniques as well as immunity to harmonics in the input signal. The effect of unbalance compensation on the PV power output depending on the irradiance and the operational region on the power-voltage curve is examined. Analysis of the DC link voltage ripple shows the region of operation on the P-V curve affects the amplitude of the DC link voltage ripple during negative sequence compensation. The proposed control scheme is validated by simulation in the Matlab/Simulink® environment. The proposed control scheme is tested in the presence of excessive current imbalance, unbalanced feeder impedances, and non-linear loads. The results have shown that the proposed control scheme can improve power quality in a hybrid PV-diesel microgrid by reducing both voltage and current imbalance while simultaneously converting real power from a PV array

Transformer-Less Cascaded Voltage Source Converter Based STATCOM

In this work, a transformer-less voltage source converter (VSC) based STATCOM is proposed with a combination of cascaded conventional three-phase voltage source inverters. This modular structure provides multilevel operation with reduced switch count and independent DC-link capacitors. The actual contribution of this paper is the transformer-less configuration of a conventional cascaded voltage source converter which provides reduced cost and volume as compared to other transformer-less converter configurations. The system provides reactive power compensation with better power quality when connected to the nonlinear power electronics load also. A simple control system is provided for balancing the Dc link capacitor voltage and reactive power compensation. The validation of the proposed model is analyzed with simulation using MATLAB/SIMULINK software and the results are obtained with different linear and nonlinear load configurations

Grid Voltage Synchronization for Unbalanced Voltages Using the Energy Operator

This paper presents a novel synchronization technique which can identify the grid voltage frequency and phase angle under unbalanced grid voltage conditions. The method combines the features of two different energy operator schemes: the basic one for estimating the frequency of the grid voltages and the cross-energy operator for phase tracking. Using a moving data window of five samples the algorithm can track the fundamental frequency and phase angle quickly and accurately. The paper discusses the fundamental principles of the method, highlights its features and filter requirements in implementation. An experimental implementation of this method is presented which validates its performance for practical operation. The ability of the proposed method to enable a STATCOM riding-through unbalanced grid voltage condition is verified by the results from a power network simulation study

Performance investigation of stand-alone induction generator based on STATCOM for wind power application

Self-Excited induction generators (SEIG) display a low voltage and frequency regulation due to variable applied load and input rotation speed. Current work presents a simulation and performance analysis of a three-phase wind-driven, SEIG connect to a three-phase load. In addition, an investigation of the dynamic operation of the induction generator from starting steady state until no-load operation. It is assumed that the input mechanical power is constant where the rotor of the SEIG rotates at a constant speed. The value of the excitation capacitance which is necessary to the operation of the induction generator also computed to ensure a smooth and self-excitation starting. The output voltage of the generator is adjusted by varying the reactive power injected by STATCOM. A 3-phase IGBT voltage source inverter with a fuel cell input supply is connected as STATCOM which is used to compensate for the reduction in the supply voltage and its frequency due to variation occurred in the applied loads. This work includes introducing a neuro-fuzzyy logic controller to enhance the performance of the SEIG by regulation the generated voltage and frequency The dynamic model of SEIG with STATCOM and loads are implemented using MATLAB/SIMULIN