Abstract

In the speed sensorless of the induction motor, the machine parameters (especially rotor resistance Rr) have a strong influence on the speed estimation. This paper presents an original method of estimating the rotor resistance of a conventional Indirect Stator Flux Oriented Controlled (ISFOC) induction motor drive. A Model Reference System (MRAS) has been formed to estimate the rotor resistance which is tuned to obtain high-performance ISFOC induction motor drive.The reference and adjustable models, developed in stationary stator reference frame, are used in the MRAS scheme to estimate induction rotor resistance from measured terminal voltages and currents. The IP gains speed controller and PI gains current controller are calculated and tuned at each sampling time according to the new estimated rotor resistance. The proposed algorithm has been tested by numerical simulation, showing the capability of driving active load; and stability is preserved. Experimental test have been carried out in order to validate the effectiveness of the proposed scheme. The controller was implemented on a digital signal processor based on dSPACE DS1104. The experimental resultants show the satisfactory behavior of the proposed approach in terms of dynamic performance.

Abstract

Distributed Generation (DG) is an emerging approach for providing electric power in heart of the power system. It mainly depends upon the installation and operation of small size, compact and clean electric power generating units at or near an electric load (customer). It has become necessary to investigate the technical and economic impact future connections of Distributed Generation on electric power distribution networks, and evaluate some of these effects of power sector deregulation.

In a power system network, proper planning and DG placement can minimize the system electrical losses, whilst improper placement could lead to increased system losses. This is utmost important since losses in any power network are proportional to the square of the current and offsetting load with DG reduces losses. B-coefficients method (Kron's loss formula or Loss coefficients method) is used to calculate the total system loss. B-coefficients are functions of the system operating state. If a new scheduling of generation is not drastically different from the initial operating condition, the loss coefficients may be assumed constant.

The factors influencing the power generation at minimum cost are operating efficiencies of generators, fuel cost, and line losses. Therefore the electrical losses will affect generation costs. Power networks with higher losses have higher fuel costs. Economic dispatch is a method of finding the real power scheduling of each plant in such a way as to minimize the total generation costs. Economic dispatch method is implemented to minimize the total generation cost.

In this paper a suitable location of the DG to improve network performance at reduced or controlled network losses, improved voltage profile and the generation cost are determined. The power system networks of 5-bus system and 26-bus systems are analyzed using MATLAB software.

Abstract

When planning a new power system, in particular at a new voltage level, insulation coordination (IC) is one of the most important subjects. The main task is the determination of stresses and the assessment of the strength of the system and the equipment installed. The general procedure of IC is described in IEC 60071. However, this standard does not give precise advice regarding new voltage levels at & above 1000 KV. However, experience is available from former CIGRE work which also considered the 1000 kV voltage level. The lightning and switching overvoltages are of particular interest regarding stresses. For determination of overvoltages the well known models and methods from various CIGRE reports are applied & corresponding examples and simulations will be presented. The overvoltages in UHV system like Temporary, Slow front, Fast front & Very fast front overvoltages are considered & dielectric strength of insulation at operating voltage, switching impulse, lightning impulse & very fast transient stress will be examined & basic design of Insulation coordination for UHV (of & above 1000 KV) is suggested. In addition, special consideration is made on the performance of SF6 insulating systems which will frequently be applied in the voltage range in question.

Abstract

This paper presents a comparative study of single-sensor based Maximum Power Point Tracking (MPPT) techniques for solar photovoltaic (PV) systems. The proposed techniques employ conventional hill climbing algorithm to find and track the MPP, using single-sensor methods which are based on either a tachometer or manometer or voltage sensor. Description and analysis of the proposed techniques are presented and verified experimentally on DC/DC buck converter controlled by a low-cost 8-bit PIC microcontroller.

Abstract

This paper describes closed loop controlled inter Line Power flow controller used in power system. An Inter line power flow controller is VSC-based FACTS controller for series compensation with the unique capability of power management among multilines of a subs-station. The FACTS technology is essential to alleviate these difficulties by enabling utilities to get most service from their transmission facilities. FACTS controllers can control series impendence, shunt impedance, current, voltage and phase angle. Different FACTS controller's circuits are simulated using PSPICE software package.IPFC is used to improve the power flow and to provide a power balance of a transmission system. The circuit model of IPFC was developed and the same is used for simulation.

Abstract

This paper proposes that is a combination of Fuzzy Logic Power Oscillations Damping (FLPOD) controller with Proportional and Integral Power Flow (PIPF) controller for Thyristor Controlled Series Capacitor (TCSC) to enhance the power system stability of multi machine power system. The proposed controller improves the performance of TCSC to effectively damp the power system oscillations after clearing fault in the power system. The TCSC with proposed controller is tested on Western System Coordinating Council (WSCC) — 9 Bus system through simulation by using SIMULINK.

Abstract

Low Frequency Oscillations (LFO) in power system occur usually because of lack of damping torque to overcome disturbances in power system such as changes in mechanical power. These LFO greatly affect the transmission line transfer capability and power system stability. PSS and FACTS devices can help the damping of power system oscillations.Traditionally, Power System Stabilizers (PSS) are being used to damp these oscillations. In this paper, we propose a systematic approach to design the damping controller for UPFC model in Single Machine Infinite Bus (SMIB) system.Unified Power Flow Controller (UPFC) is a well-known FACTS device that can control power flow in transmission lines. It can also replace PSS to damp low frequency oscillations effectively through direct control of voltage and power. In this paper a linearised Heffron-Philips model of a (Single Machine—Infinite Bus) power system with a unified power flow controller is developed. A proposed fuzzy logic based UPFC controller adjusts four UPFC inputs by appropriately processing of the input error signal, and provides an efficient damping when compared to conventional damping controller and PID controller. The simulations are performed in MATLAB/SIMULINK environment with necessary command lines. The results of the simulation show that the UPFC with fuzzy-based controllers is more effective in damping LFO compared to UPFC with damper controllers and PID controllers.

Abstract

In this paper Radial Distribution Systems (RDS) analysis with embedded series Flexible AC Transmission System (FACTS) devices is facilitated by formulation of power flow equations with bus voltage magnitudes and line flow as independent variables. Since control variables such as the line and bus reactive powers figure directly in the formulation, handling the control action of FACTS devices in the distribution system is direct and easily implemented.Here we are using Thyristor Controlled Series Capacitor (TCSC). Distribution lines have high R/X ratios, leading to the convergence problem in the traditional approaches. The major objective of FACTS devices installed on a distribution feeder are to improve voltage profiles, correct power factor and reduce losses Using the Breadth-First-Search (BFS). The bus incidence matrix of a radial distribution system is first rendered strictly upper diagonal, leading computational effort. All the common FACTS device models under steady-state conditions are easily incorporated in the new framework by a simple process of “variable swapping”. Using IEEE standard systems, the Line Flow-Based (LFB) formulation is shown to provide easy implementation with multiple series and shunt FACTS devices in the system and enable direct evaluation of the FACTS device ratings.

Abstract

This paper describes the indirect adaptive fuzzy control of doubly fed induction machine with both its stator and rotor fed by two PWM voltage source inverters in which the system operate in stator field oriented control. Associated to Takagi- Sugeno fuzzy model, an indirect adaptive control has been applied to a simplified structure. The development of this model is carried out in two stages. The first stage consists in estimating the parameters of a fuzzy model. In the second, the control is provided by a fuzzy controller based on the torque calculated method. Simulation study based on idealized motor and inverter models is conduced to show the effectiveness of the proposed method.