I'm planning to work on optimization of switch allocation in existing distribution network. I have no working on distribution system before. My question is, what are the considerations in moving a sectionalizer from a location to another? Can I just move sectionalizer near the substation to the end side of the network? Is a sectionalizer chosen to be placed in a specific location only?
Hi Johanno,
First of all, the purpose of sectionalizing switches is mainly to isolate faulty section of the network so that a total (partial) blackout is avoided. This effectively means such switches reduce the amount of load being shed in the event a fault occurs elsewhere. In a radial network, suppose a fault (such as broken wire) occurs in a feeder close to a substation or the feeder is under maintenance. Only that line can then be disconnected from the rest of the network. The demand is fed with alternative path(s) by closing normally open switches (which are often called tie-switches). So, generally, the more switches you have in a distribution system, the more robust and reliable the system is. With regards to the allocation, the trivial solution is to place one in each feeder. This is perhaps the best solution from the reliability point of view. However, this is without considering the cost of switches (capital, installation, operation and maintenance). Placing the switches should therefore be weighed from the benefit it brings about in terms of reliability. For instance, a switch near the substation is likely to have higher impact than one the end of the radial network. Well, this may not always be true. For instance, it may sometimes depend on other factors (for example, whether the system has distributed energy resources, etc.). I reckon the optimal location of switches depends on the location of distributed energy resources. Anyway, the problem of switch allocation in distribution systems leads to a mixed integer nonlinear programing, a combinatorial optimization problem. A possible objective function is to minimize the sum of reliability, capital, installation and annual O&M costs. The best (optimal) locations of switches are those that lead to the global optimal solution of such a problem i.e. those that achieve the best trade off between reliability and cost.
I am afraid one cannot tell the best location by simply seeing the network. Perhaps, there are some rules of thumb, which I am not aware of.
I hope this helps.
Cheers!
Desta
Dear Johanno
If you want to put sectionalizing switches in the distribution network you need to set optimization function and what do you want to optimize? Do you want to minimize losses, or do you want to maximize reliability (minimize reliability indices, SAIFI; SAIDI; CAIFI; CAIDI; ENS ...) including the capital, installation and annual O&M costs.
As Desta Zahlay already said you need to set objective function and solve it. The solution will be the number and location of sectionalizing switches. There are may paper about that matter.
Srete
maybe i can help you but need more explanation what you want exactly!
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