Zubair Ahmed Memon

Impact of distributed generation on network short circuit level

Distributed generation (DG) technology is spreading rapidly owing to advantages of clean environment, loss reduction and voltage improvement. Utilities in Pakistan are welcoming all generations to increase their supply capacity. Industries are installing DGs to meet their load requirements. In order to reduce energy bills, DGs are being used to supply spare power back to utility or even in off peak durations. DG interconnection changes electrical network characteristics of existing utility network. Protection problems may occur in the form of relay settings, islanding and increased short circuit currents. This paper investigates the effects of DG interconnection on short circuit currents. A feeder of SITE industrial area of Karachi is modeled and simulated for short circuit analysis. Analysis shows that DG interconnection to a radial feeder increases short circuit level at all nodes of the feeder.

Analyzing the Impacts of Distributed Generation Integration on Distribution Network: A Corridor Towards Smart Grid Implementation in Pakistan

Renewable power generation sources used as distributed generations (DGs) are increasing rapidly all around the world. Apart from environmental advantages, DGs result in reduction of power losses, improvement of bus voltages, increased system reliability, stability, power quality and ease of operation. In this work, the impacts of DG on power losses, bus voltages and short circuit level of the power system are investigated with different case strategies of DG interconnections. With every strategic case, the DG impacts on power system are analyzed by network simulation through Power System Simulator Siemens Network Calculator software (PSS SINCAL). Significant power losses and voltage improvement were observed depending on size and strategic locations of DG interconnections. Slight increase in network short circuit levels is observed within permissible limits of protection devices. The communication prospects of DG and Smart Grid Integration are also discussed to enable the monitoring, control of interconnected DG units with a two-way electricity and information flow to develop an automated distributed energy network. Finally, an attempt is made to strategize a simple and gradually applicable model of controlling the network conditions through the integration of DGs. Using the state of art of DG integration models, the gradually implementable smart grid system is proposed for under developed countries, like Pakistan.

Adaptive Neuro-fuzzy Inference System Design of Inverted Pendulum System on an Inclined Rail

The basic aim of our work was to design appropriate controller to control the angle of the pendulum and the position of the cart in order to stabilize the conventional inverted pendulum system on an inclined rail. We improved the adaptive neuro-fuzzy inference system (ANFIS) on the basis of conventional fuzzy controller. A neuro-fuzzy hybrid approach was used to design the fuzzy rule base on a basis of building a Sugeno fuzzy model in order to swing a pendulum attached to a cart from an initial downwards position to an upright position and maintain that state. The adaptive neuro-fuzzy logic controller was designed in the Matlab-Simulink environment. By training and checking of effective data, the results proved that the adaptive neuro-fuzzy controller had good performance about stability in the real-time control of the inverted pendulum on an inclined rail.

Estimation of Compensation Current Reference using Fuzzy Logic Controller for Three-Phase Hybrid Active Power Filter

ABSTRACT This research deals with design of three-phase hybrid active power filter to reduce the current distortions caused by non-linear loads. The Instantaneous Active and Reactive Power Method (p-q) is used to perform the identification of disturbing currents. The p-q algorithm generates the reference compensation current signal, while this generated reference compensation current signal is exactly followed by the output current of the voltage source converter. Fuzzy logic controller for three-phase hybrid active power filter is used to generate the switching signals in order to control the output currents of voltage source converter. Simulation results showed that the hybrid active power filter can compensate the harmonic currents effectively and improve power quality. Keywords Hybrid Active Filter, p-q theorem, Total Harmonic Distortion, Fuzzy Logic Controller. 1. INTRODUCTION Nowadays industries prefer to use power electronics based devices due to their effectiveness. Though these power electronics based devices are advantageous to the electronics and electrical industry, these devices generate and inject the harmonics in the power industry. These harmonic are known as electrical disturbance which is the main cause of the power quality associated harms. The industrial process is affected by the power quality problems. Therefore for improving the quality of the power supply this harmonic distortion should be decreased with the help of the filters. In the literature, various topologies of active power filters (APFs) have been presented for mitigation of harmonics [1-3]. The APF topologies are not cost-effective for the application of high power because of their high rating and very high switching frequency of pulse width modulator (PWM) converter. Thus LC passive filters (PFs) are used for harmonic filtration of such large nonlinear loads. Low cost and high reliability is the main advantage of PFs. However, PFs suffer from some shortcomings for example, the performance of these filters is affected due to the varying impedance of the system and with the utility system the series and parallel resonances may be created, which cause current harmonics increase in the supply [4-5]. As discussed above both APFs and PFs suffer from a number of disadvantages. Therefore another solution of harmonic mitigation, called hybrid active power filter (HAPF), has been introduced. Hybrid active power filters (HAPF) provide the combined advantages of APF and PPF and eliminate their disadvantages. These topologies are cost effective solutions of the high-power power quality problems with well filtering performance. This research paper is restricted to the (HAPF). The (HAPF) is specially designed to compensate the reactive power and decrease the harmonic currents occurred on the side of load from the grid, by injecting the current having same magnitude but opposite in the phase direction of the harmonic current [6]. In the literature a number of methods have been emphasized for identification of reference current [7-12]. For identification of disturbing current the instantaneous reactive power method has been used in this paper. For controlling the output currents of the converter, to follow the reference currents, hysteresis current controller have been used in [13-15].The implementation of hysteresis current controller is simple and its performance is also excellent. However, this controller suffers from drawbacks. Its main drawback is to generate the variable switching frequency. Therefore reliability and efficiency of hybrid active power filter is affected [16]. To avoid these drawbacks, this paper present the fuzzy logic based current controller to control the output currents of the voltage source converter. Although to control the output current of converter based on fuzzy based is not new [17-18], this approach with 15 rules has not yet being applied to proposed filter.

Power Quality Improvement in QUCEST Larkana Campus by Using Three Types of Power Filters

The increase of power electronic converters at the end-user side is unavoidable and it will cause current harmonic distortion and wide range of disturbance in the power system (PS). This paper presents current harmonic compensation for the test case of the Quaid-e-Awam University College of Engineering Sciences and Technology (QUCEST) Larkana campus in MATLAB SIMULINK by using three types of power filters i.e. passive, active and hybrid power filters. The purpose of this experiment and simulation model is to analyse and find out the best solution for reducing the current harmonic and unbalanced load condition at the incoming transformer to the campus. Moreover, this paper presents the testing and comparison of the active and hybrid power filters by using the combined design technique of harmonic compensate control system based on Unit Vector Template (UVT) and Instantaneous Reactive Power (IRP) theory. The simulation results allow to identify the effectiveness of the control system along with passive filter. Based on the testing and simulation results of three types of power filters, hybrid power filter has the maximum ability to mitigate the current harmonic in the system, and it also reduces the neutral current thus causing less stress in the existing system.

Investigation and design of an active power filter for PQ issue at QUCEST larkana campus using MATLAB/SIMULINK

This paper will discuss the modeling of three-phase four wire active power filter (APF) for Quaid-e-Awam University College of Engineering Sciences and Technology (QUCEST) Campus at Larkana, Pakistan. The control strategy of the APF is based on the Unit Vector Template (UVT) method and Instantaneous Reactive Power (IRP) theory. The function of UVT method is for obtaining the voltage signals for the control system when source voltages are distorted. The phase locked loop (PLL) is used to make sure that the detected source voltage is at the correct phase angle. This voltage signal will be used to determine the reference current for the APF. MATLAB Simulink software is used to design and simulate the case. The simulation result of APF will prove that the designed control system able to reduce the system harmonic and unbalanced load problems that caused by nonlinear loads and transient condition.

Identification of harmonics of three-phase six-pulse rectifier with different kind of loads in MATLAB and fabrication model

Power electronic converter is known as nonlinear device. Due to its conversion characteristic it drags and draws the source current from the power source. These characteristics make it to generate harmonics that will degrade the grid power quality (PQ). The effects of harmonics include malfunction of connected sensitive equipment such as protective relay and overheating of winding equipment like transformer and motor. Therefore, it is needed to identify the source of problems and deal with it. This paper analyses the harmonics behaviour of the three-phase six pulse (full wave) rectifier model that usually is used in industrial load applications with MATLAB software and test the constructed a fabricated circuit with PQ analyser. The results obtained from the fabricated model will be useful as the nonlinear load model for designing various types of filters to mitigate the current harmonic distortion.

Real-time vehicle detection based on quasi-shot segmentation

In this paper, a Quasi-shot Segmentation Vehicle Detection (QSVD) method is proposed to improve the accuracy and robustness of traffic flow detection. The QSVD method is based on histogram intersection method to find the biggest difference between successive frames. Adjacent frames are considered in when vehicle is detected in current frame. Relying on the QSVD method, vehicle can be detected by signal peak and valley search and gradual transition shot detection problem can be resolved. The initial video is used to accomplish detection directly without image preprocessing. Experiments show that vehicles can be detected effectively by the QSVD method. The detection accuracy is remained at 93% or more.