M. P. Selvan

Fuzzy Embedded Genetic Algorithm Method for Distributed Generation Planning

Abstract This article proposes a novel methodology that employs fuzzy set theory and the genetic algorithm for formulation and evaluation of a multi-objective function, respectively, for optimal planning of distributed generator units. The effectiveness of the proposed method is tested using various systems of different sizes and configurations and is validated by comparing the results with that of the weighted sum method. The dependence of existing methods on global preference information of decision maker is overcome in this method. Further, different types of distributed generator models are also employed to demonstrate the importance of the use of a precise distributed generator model and the adaptability of the proposed method in distributed generator planning studies.

Distributed Generation Planning: A New Approach Based on Goal Programming

Abstract This article proposes a novel methodology that employs a goal programming technique and genetic algorithm for formulation and evaluation of a multi-objective function, respectively, for optimal planning of distributed generator units in the distribution system. The multi-objective function consists of various performance indices that govern the optimal operation of a distribution system with distributed generator units. The proposed method aims to greatly diminish the dependence in existing methods on the global preference information of the distribution system planner by means of simplicity in problem formulation utilizing a goal programming technique. The capacity of the distribution system to accept distributed generator integration is evaluated such that with the placement of every additional distributed generator unit, the value of multi-objective function reduces without any violation in the system operating constraints. The effectiveness of the proposed method is tested using various distribution systems of different sizes and configurations, and the results are validated with the existing methods, namely the iterative genetic algorithm method and the fuzzy embedded genetic algorithm method. Further, different types of distributed generator models are also employed to demonstrate the adaptability of the proposed method in distributed generator planning studies.

Planning and operation of Distributed Generations in distribution systems for improved voltage profile

An optimal way of real and reactive power management in radial distribution systems with Distributed Generations (DG) to improve the voltage profile is presented in this paper. Distributed generations effectively reduce the real power loss in radial distribution system compared to other methods of loss reduction and simultaneously improve the reliability of the system. In this paper, a solution methodology based on the voltage stability index has been proposed for optimal siting of distributed generations. The optimal sizing of the sources has also been carried out using genetic algorithm for better voltage regulation, voltage stability index and reduced network power loss in the radial distribution system. An emphasis is laid in this paper on the application of Wind Turbine Generator System (WTGS) because of the distinct behaviour of the induction generators present in them. A detailed performance analysis is carried out on Indian 25 bus system, 33 and 69 bus systems to demonstrate the effectiveness of the proposed methodology.

Distribution system load flow using object-oriented methodology

Distribution system has been analyzed in this paper using object-oriented approach. The important contribution of this paper is the development of software objects for various distribution system components in such a way that they can be reused in most of the distribution system analysis programs. The design, proposed in this paper, is used for developing load flow analysis program. Object-oriented design replicates the physical system structure exactly in the software. The extensibility of the object-oriented design is exploited to extend the radial load flow analysis module for performing the load flow analysis of weakly meshed system by deriving few specialized objects from the fundamental objects used for radial load flow. Modeled objects are implemented in C++, an object-oriented programming language, and tested with various test systems. The results obtained for 69-bus radial system and 33-bus weakly meshed system are provided. This design is being extended for developing load flow analysis module for 3-phase unbalanced distribution system and distribution system with dispersed generations.

A Hybrid Genetic Algorithm based Power System Stabilizer

This paper presents a novel hybrid power system stabilizer (HyPSS), which is a parallel combination of conventional delta-omega power system stabilizer (CPSS) and fuzzy logic power system stabilizer (FLPSS). HyPSS is aimed at improving both transient and dynamic stability of the system. CPSS parameters and normalization and de-normalization factors of FLPSS are optimized using genetic algorithm (GA). Simulation results of multi machine power system reveal that the performance of HyPSS is quite robust to wide variations in loading conditions both for small and large perturbations.

A simplified approach for load flow analysis of radial distribution network with embedded generation

This paper presents a simple approach for load flow analysis of a radial distribution network with embedded generation. The proposed approach utilizes forward and backward sweep algorithm based on Kirchoffpsilas current law (KCL) and Kirchoffpsilas voltage law (KVL) for evaluating the node voltages iteratively. In this approach, computation of branch current depends only on the current injected at the neighbouring node and the current in the adjacent branch. This approach starts from the end nodes of sub lateral line, lateral line and main line and moves towards the root node during branch current computation. The node voltage evaluation begins from the root node and moves towards the nodes located at the far end of the main, lateral and sub lateral lines. The proposed approach has been tested using three radial distribution systems of different size and configuration and is found to be computationally efficient. The effectiveness of the proposed approach is further demonstrated by integrating the embedded generation into the load flow analysis of the radial distribution network.

Comparative evaluation of performance of different control strategies on UPQC connected distribution system

This paper presents a comparative analysis of steady state behaviour of UPQC with three different control techniques, when connected to a distribution system to protect sensitive loads against power quality problems. The control strategies based only on hysteresis, SPWM and a combination of both for controlling the firing pulses of shunt and series APFs of UPQC are discussed. In common, PI control is used for maintaining DC link voltage. PSCAD/EMTDC is used to model the UPQC connected to a RL load. The simulated model is tested with all the three control strategies and the results are verified for voltage sag and swell compensation. A comparison is made between the control schemes, taking in account of the current through shunt APF and current at the point of common coupling (PCC). The results are appreciable when hysteresis type control is applied to shunt APF and SPWM control to series APF.

Embedded Control of n -Level DC–DC–AC Inverter

A generalized multilevel inverter (MLI) with frontend dc-dc conversion stage followed by a synchronized H-bridge is presented. By using this configuration along with the proposed embedded control, any desired number of levels (n) in the output voltage can be produced. The dc-dc conversion stage employs an asynchronous buck converter. The duty cycle of dc-dc converter is varied in the form of m-level piecewise constant (PWC) unidirectional sine wave to produce a similar output voltage across the dc-link capacitor. The unidirectional PWC voltage is made into n-level ac voltage, where n = (2m - 1), by the synchronized H-bridge. Hence, it is named as dc-dc-ac MLI. An 8-bit Xilinx SPARTAN 3AN field programmable gate array (FPGA)-based digital controller is utilized for the simultaneous generation of high-frequency switching pulses for dc-dc converter and synchronized fundamental frequency switching pulses for H-bridge. The desired number of levels in ac output voltage and its frequency are the essential inputs to the pulse generation algorithm implemented in FPGA. The proposed MLI is simulated in MATLAB/Simulink environment; its functioning is verified with resistive (R) and resistive-inductive (R-L) loads. The hardware prototype of MLI is built in the laboratory and its performance is validated with R, R-L loads, and few home appliances.

Intelligent Residential Energy Management System for Dynamic Demand Response in Smart Buildings

The advancements in renewable energy technologies direct the power sector to focus on power generation from renewable energy resources (RER) as an alternative solution for meeting the future demand. Nowadays residential buildings are becoming smarter with wide use of smart appliances, integration of information and communication technology, and in-house power generation using RER. In this paper, an intelligent residential energy management system (IREMS) for prosumers of smart residential buildings is proposed, and its benefits are demonstrated through a case study. The primary objective of IREMS is reduction in electricity bills while maintaining the power demand under the maximum demand limit subjected to the various constraints governing the operation of household loads and RER. The IREMS achieves the objective by scheduling the schedulable loads during low pricing intervals while considering the operational dynamics of nonschedulable loads and availability of RER. IREMS also manages the battery energy storage in such a way so as to reduce the power dissipated through the dump load when excess power is available from RER due to the utility-defined power export limit to grid. Further, an optimal resources sizing algorithm is used to choose the size of RER and battery storage for the effective utilization of available renewable energy.

Design, Operation, and Control of S3 Inverter for Single-Phase Microgrid Applications

A single-phase voltage source inverter with a front-end dc-dc conversion stage followed by a synchronized push-pull configuration operating at a desired fundamental frequency (FF) is presented. The duty cycle of the dc-dc conversion stage is varied in the form of a unidirectional sine wave to produce a similar output voltage across the dc-link capacitor. The unidirectional voltage is made into an alternating voltage by the synchronized push-pull configuration. This inverter employs three semiconductor switches, in which one is operating at a high frequency and the rest are operating at an FF. Hence, it is named as the S3 inverter. Furthermore, simple and cost-effective analog circuits are presented for the generation of switching pulses and the control of the amount of power fed to the grid. The hardware prototype of the S3 inverter has been built in a laboratory, and its performance during the stand-alone and grid-connected modes of operation is validated.