Study And Implementation On Substation Locating And Sizing

Substation locating and sizing is a key task for power network planning. TianjinUniversity has developed the substation locating and sizing planning subsystem ofdecision support software CNP for urban power network planning. On the basis ofresidence region load forecasting, this subsystem could get the new substation's site,size and power supply area by optimal searching on a large range without designatingthe site and quantity of candidate substation in target year in advance. This paper hasperfected the function and improved the locating methods of this software. The mainworks include:(1)By the study on alternative allocation location method for substation locatingand sizing, it's shown that the model and algorithm of this method is under theassumption condition that the load value difference of the whole load point would notbe great or there would bring greater error. However, in the real projects, loaddistribution forecasting result is often failed to meet this condition. Especially on thecondition of current society and economic development, the cities are developingrapidly and various loads are expanding sharply which lead to the more and moregreater difference between a single-point load value and region load value so that thelocating result is not the optimal and there even appear that two substations are tooclose or overlapped. Whereas this issue, this paper proposed an improved model andmethod for substation locating and sizing in view of great single-point load value. Bymeans of geographic information of this load region, this method would take the greatload point load decomposing before substation locating to meet the assumptioncondition's requirement of existing locating model method's and then be combinedwith alternative allocation location method to work out the optimal solution. At thesame time, this method also resolved the issue that the calculation results of powersupply region were unreasonable when the single-point load is great. At last, theprogram based on this method has been verified by examples and we reached theexpected result.(2)The existing alternative allocation location method is only suitable for targetyear locating and this paper proposed a mid-year substation planning method whichhas taken both mid-year's load distribution and target year's substation site location capacityinto consideration. On the basis of Branch and Bound Algorithm, this methodbrought the concept of"power source point– load point"arc value. Taking the arcvalue as judgment basis, it would optimize the capacity of substation and the load sizeand quantity to reach the result of load distribution. At first, it listed all the arcsbetween candidate power and all the load points and orders those arcs and then itwould choose the arcs starting from the arc with the least arc value. After eachchoice,it would take out all the arcs combined with the relevant load points and takeaway the load value from the capacityof relevant candidate power point, and continueto choose another one from the left arcs until all the load points would be distributed.At last it achieved the optimization selection plan. This method has been shownfeasible byexample.(3)This paper has realized the above two methods in programming the computerassistant decision support system of urban power network planning, upgraded andimproved the substation planning subsystem of the existing system with a clear aim,and developed the new functions including verification before locating and avoidingsites not suitable for substations.