There is a movement of sorts going on all over the world. For the sake of reducing our carbon footprints, the work going on in the arena of renewable energy is going on fullscap. This is happening more so in distribution networks.
In reality, the penetration of creating sources in distribution networks has a direct bearing on its features. Also, it has a definite effect on other technical nuances hinging on its size and location in the existing framework.
It is a known thing that the integration of a distributed network into a system which already exists brings about a lot of change in it. The power system protection is one of the chief criteria. For one, the short circuit power of a distribution system undergoes a change of sorts when a few of the generators are taken away from it. This can lead to elongation of fault clearing time and disconnection of equipment in the distribution system or inessential working of protective instrumentation.
Distributed generation units can take away the stress on utility systems. They can also hike up the reliability factor quite a bit. However, what is also well understood is that the interconnection of DG units and utility grids is not all that simple a task. A sizeable number of distribution systems are structured to get the maximum out of power delivery in one direction.
It is an accepted fact that DG installations of any type or size can cause a bit of a stir within the system. There is, nonetheless, an upper limit to how many DGs one can add onto an existing system without enhancing its cost factor to a large extent.
A great many number of distribution systems, more so in the case of those set up in rural areas, are organised in a radial configuration. This format permits simplicity of operations but also results in a few anomalies. One of the most important piece parts of this system is the fuse. This has a direct bearing on the functions of the other overcurrent protection devices or the OCDs. Also, putting the utility breakers and reclosers so that they can function in close conundrum with the fuses is termed as co-ordination of the OCDs. The reason for this co-ordination is to reduce any kinds of blockages to the customers as and when a break happens in the system.
In a system which is radial, fault clearing needs a single device only since only a single source gives the current to the fault. In the case of meshed network systems, breakers are needed at both ends of the faulted line for it to open. With DG, it is a number of sources which come into the picture and opening only the utility breaker does not ensure that the fault will be cleared up fully and quickly. It is quite an expensive proposition to change over the distribution system’s protection format so that it will function like a meshed transmission system. The way out in this system is to get the DG to block out from it when a fault comes up. Then the system will come back to an actual radial configuration and the usual fault clearing can take place.