Topics: Electricity distribution, Dummy load, Transformer Pages: 11 (3443 words) Published: January 16, 2013

1.1 Background and Objectives
1.1.1. Background
In developing countries like ours Grid power is either inadequate or unavailable in the remote and inac move the need for long and inefficient transmission lines. If a suitable water source is available nearby, Micro-hydro is one of the reasonable and cost effective energy technologies to be considered for rural electrification. Hydroelectric systems having capacity of 100kW or smaller are considered as Micro-hydro power. It allows the utilization of hydroelectric potential of small rivers without any significant costs on dams and civil structures. It is generally of run of river type. Micro-hydro has been playing significant role in providing electricity to the local communities in remote areas. Generally synchronous generators are used for the generation purpose in these Micro-hydro plants. In any power system it is required that the voltage and frequency of the system remains within the limits. But in case of Micro-hydro system there appears a common problem; with different loads used by the consumers there is fluctuation in the turbine speed and hence the frequency generated by the generator which causes adverse affect in various electrical appliances. So in order to control the voltage of synchronous generator, its excitation is controlled; whereas the frequency can be controlled either by controlling of value of mechanical power input to the generator or by varying the electrical load. Mechanical power input can be controlled by a control system known as Mechanical Governor. It operates as a valve on the turbine inlet that can be closed to restrict the flow of water (and therefore the power) going into the turbine to match the current electrical loading. But this method of frequency control is expensive for Micro-hydro system and also its response is slow. So this method is not adopted for micro-hydro system. So, for the control of the frequency in a micro-hydro system an Electronic Load Controller (ELC) is used. Electronic load controller can be defined as electronic control system used to stabilize the output of generator (frequency) when the consumer loads changes. The control is done by diverting the unused power to the dummy load (ballast). The diversion process is done through power driver circuit based on the change of frequency on the system. In principle the purpose of ELC is to make sure that power generated by the turbine is the same with power consumed. This controller is easily accessible with little technical knowledge and training than the Mechanical Governor. cessible locations. In such locations Stand-alone power generation plants can provide an answer since they re

1.1.2 Motivation
The concept of Electronic Load Controller as the Final year project was developed based on the ELC present on the Turbine Testing Lab (TTL) at Kathmandu University. The lab set up in TTL consists of a 20kW synchronous generator with AVR installed in it. Its output frequency needs to be monitored according to the load variation. For that there is an ELC and the total dump load of 18 kW. So, this project will be analyzing and designing a system with stable frequency for various loads using the available resources in TTL.

1.1.3 Objectives:
The main objectives of this project are as follows.
Design and fabrication of an ELC using chopper controlled dump load.
Fabrication of MOSFET based chopper driving circuit for proper load management.
Microcontroller programming to monitor the supply frequency and control the chopper driving circuit.
Design of microcontroller based control circuit for the proper allocation of power to the dump load.

1.2 System overview
1.2.1 Block diagram

Fig(1) :- Block diagram of system

Complete model of this project is represented by the block diagram above. Design of each of these modules and their final fabrication completes this project on ELC....
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