K. Vinothkumar

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.

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.

Novel Coordinated Converter Control (3C) Strategy for Enhancement of Fault Ride-through Capability of Doubly Fed Induction Generator Wind Farms

Abstract A novel coordinated converter control strategy is proposed in this article for enhancement of the fault ride-through capability of doubly fed induction generator based wind farms. The proposed coordinated converter control strategy is activated only during the instance of fault clearance in order to achieve rapid restoration of terminal voltage and thereby enhance the post-fault performance capability of wind generators connected to the distribution network. An extensive simulation study is carried out employing PSCAD/EMTDC software (Manitoba, Canada). The simulation results demonstrate the laudable performance of the doubly fed induction generator achieved by employing the coordinated converter control strategy.

Impact of DG model and load model on placement of multiple DGs in distribution system

Placement of multiple distributed generators (DG) in distribution system is addressed in this paper. A multiobjective index, formulated by combining the appropriately weighed diverse performance indices, is evaluated using Genetic Algorithm to assess the suitable locations and sizes of DG units to be placed. The impact of DG model on DG siting and sizing are also addressed considering different voltage dependent load models. The simulation study is carried out on a typical 25 bus Indian system and the results of the study show that the DG model significantly affects the placement location, size of the unit and penetration level (sum of the size of DG units) in a distribution system.

Grid Integration of Distributed Generation-Consequences on Node Voltage under Grid Perturbations

Wind generators are very popular in most parts of the world as distributed generations (DG) owing to their technological advancement for grid integration, minimal environmental impact and free abundant availability. These wind generators usually employ induction machine for their electric power conversion due to its control simplicity and robustness in construction. The power output of such induction generator based wind turbine generator system (WTGS), depends on the node voltage and frequency of the connected radial distribution system (RDS). The node voltages of RDS are however subject to change due to variations in loading conditions. Therefore, a requirement arises to analyze the resulting mutual effect on the node voltages of RDS embedded with DG during such grid perturbations. Hence, the consequences of DG on the node voltages of RDS under anticipated small grid perturbations such as slow variation in grid frequency and connected loads are presented in this paper. The analysis is carried out on a practical Indian 25 bus radial distribution system embedded with different types of DG. From the results presented, it is observed that RDS embedded with fixed speed stall regulated WTGS are largely prone to voltage deviations at all nodes.

DG planning method for enhancement of voltage stability margin in distribution system

This paper presents a new methodology for multiple distributed generator (DG) planning in a radial distribution system for enhancement of voltage stability margin. An index, called voltage collapse index, has been utilized in this paper for identification of nodes that are susceptible to voltage collapse and requiring DG integration. The size of DG unit to be integrated at the identified site is determined by optimizing a multiobjective index such that reduction in network power loss and improvement in node voltages are resulted without any violations in the network operating constraints. The effect of different types of DG and load models in the identification of grid integration points and size of DG units is also studied in detail. The proposed method is tested on 11 kV Indian 25 bus system and is found to be very effective in identifying the suitable location and size of multiple DG units for enhancement of voltage stability margin.

Control Scheme for Mitigation of Output Power Fluctuations in Grid Connected Wound Rotor Induction Generator

Various dynamic slip control topologies for control of grid connected wound rotor induction generator (WRIG) are presented in this paper. An elegant control technique based on rotor voltage measurement for mitigation of output power fluctuations in grid connected schemes of WRIG, due to wind speed variation and tower shadow effect has been proposed and explained. The control of WRIG is achieved by employing the principle of chopper control for varying the rotor voltage (resistance). This technique has been utilized to achieve desired amount of real power flow into the grid from WRIG. The described dynamic slip control topologies and the control algorithm have been simulated using PSCAD/EMTDC software and are experimentally validated.