Generator Protection Measures - Thesis Example

Generator Protection Measures Abstract This project focuses on generator protection measures. It outlines some of the common but necessary requirements that must be undertaken to ensure safety of people. Protection of generators have come a long way from the simplest methods to the complex and more sophisticated ways we know today. This is also to ensure the safety of materials or appliances in use. In so doing, many outages which come as a result of power failure or excessive heat will be regulated to protect the generator and other machines. Much of the details are discussed below. Introduction Principally, generators are machines which are designed to carry out specific function. One of the primary function of a generator is to provide power to a given number of appliances. Generally, generators are used in almost all parts of the world others serving as standby generators in case of power outages. Generators therefore do not operate in an ideal condition but are subjected to failure and other problems. It is therefore necessary to wear protective clothing and take other necessary measures to curb such problems. This problem is also taken care of by the manufacturers by ensuring that they produce machines with high load factor to guarantee the safety of the civilians or the people who operates it in case of failure or during maintenance. Furthermore, after taking care of all the precautions that might occur faults associated with electrical or even mechanical persists. Most manufacturers globally have embraced the use of relays. Fundamentally, relays are electric devices which acts as circuit breakers in case of a problem. It is always standby and when a problem of overvoltage occurs it immediately disconnects the power line to the appliances or even disengages and shutdown the generator in order to ensure that machines or other devices do not get damage as a result of power disruption. DigiSilent Software Digisilent software is principally one of the most applicable software in generators. It is the most convenient software to use owing to its several advantages like general functioning incorporation, wide range of modelling in terms of distribution and transmission which produce the best analysis. In order to eradicate some outages in the generator, it is recommended to use Digisilent software to achieve maximum protection as far as electrical or mechanical faults are concerned. General generator protection Thermal protection Thermal protection is one of the most fundamental aspect of safety that must be undertaken. It is carried out to reduce the impact of overheating. Some of the devices which are constraint or need to be protected encompasses the following; thermostats which must operate normally with a current less than 2.5A, thermistors which temperature sensors used to detect thermal effect which regulate the temperature beyond certain level. Another thermal protection is the thermo-resistance which is a device that detects heat which its resistance fluctuates with temperature change. Space heaters Generators must be fitted on with space heaters that prevent any water from condensation when the generator is not in operation. Such devices should be kept switched on always and no sooner the generator starts than the space heaters switches off immediately. This is to ensure maximum protection of the winding which might get damaged while machine is in operation. Auxiliary coil protection In order to ensure safety, generators are fixed with an automatic coil fuse protection of 5A essentially connected in series with auxiliary coil. While in operation, the fuse currently in use can be replaced by another with the exact value in order to increase the factor of safety. Mainly, the purpose of the fuse is to protect the machines and other appliances in use in a number of ways for instance, it eliminates short-circuiting that might occur and also acts as protection in case the voltage regulator is not working or not working. Diode protection It is one of the general and vital protection that must be observed. Usually, it involves the use of varistor or capacitors which fixed to the generator. They will act as protection mechanism on the generator and takes care of unforeseen problems. In case of damage, such devices should be replaced with new ones to ensure maximum protection of the system. Regular protection It is carried out before the generator is operated. Such protected undertaken at lower frequency must be set at over 92% of the rated frequency. This is to ensure that the regulator is kept switch off until the generator catches up the optimum speed in order to avoid large currents in the auxiliary coil. It is the best way because it regulates voltage anytime the frequency goes down below the minimum (92%). Faults analysis Simulation is a process of inspecting, monitoring of faults automatically. It’s aimed at reducing the problems encountered as a result of faults. Through simulation, the following can be achieved Various faults exists such as ; Stator Protection Stator protection is another method for generator protection. The coiling of the stator is basically insulated. Stator protection can be phase to earth fault, phase to phase fault or even inter turn fault. Phase to earth fault To start with, phase to earth fault is normally a rare occurrence as well as inter turn fault. Such faults are constrained by resistivity of the resistor. Majorly, the insulation is place in between the two phases that is the coil and the underlying iron core. Additionally, this makes phase to phase a rare occurrence too. Earth-fault protection In this case, the generator is fixed with neutral wire that acts as an earthing. This will help to discharge excess charges into the earth as a result reduces the damage effect. Lastly, the most commonly occurring faults are the electrical faults. Other faults is from mechanical malfunctioning of the system which destroys or interferes with the insulating fabric material. Rotor earth-fault protection The circuit can be subjected to various conditions such as thermal or physical aspects. The output can result to a breakdown in the insulation segment between the winding and the rotor iron in a section where the stress might be too high. Single Line-to-Ground (SLG) Faults This essentially occurs when the network is unbalanced by the fault. The working of the coupling sequence principally depends on the type of fault. Line-to-Line (LL) Faults Such faults occurs basically when the two separate conductors touch each other. Double line-to-ground (DLG) In this scenario, it is quite different with line to line fault because of the aspect of the ground. It essentially occurs when the with fault line conductors touch each other as well as the ground. Conclusion As outlined and detailed above, it is necessary to carry out generator protection in order to take care of unforeseen problems. It is very necessary in order to eliminate some of the electrical as well as the mechanical faults which are the major causes of inefficiencies in machines. With such preventive mechanisms, it will lead to safety in places of work thus encouraging a conducive and save environment. References Kundur, P. (1994) Power System Stability and Control, McGraw-Hill, ISBN 0-07-035958-X Johansson E., et al.,(2002)Location of Eigenvalues Influenced by Different Models of Synchronous Machines, presented at the sixth IASTED International Conference Power and Energy Systems, Marina del Rey, California, USA Slootweg J.G. et al.,(2002)A Study of the Eigenvalue Analysis Capabilities of Power System Dynamics Simulation Software, 14th PSCC, Sevilla. Martins, N. and Lima,L.(1989)Eigenvalue and Frequency Do-main Analysis of Small-Signal Electromechanical Stability Problems, IEEE Symposium on Application of Eigenanalysis and Frequency Domain Methods for System Dynamic Performance, publication 90 TH 0292-3 PWR, pp 17-33, Rogers, G. (2000) Power System Oscillations, Kluwer Academic Publishers. PTI, PSS/ETM 29 Program Application Guide, October 2002. “IEEE Guide for Synchronous Generator Modelling Practices in Stability Analysis, IEEE Std 1110-1991 Read More