Coordinated Planning Of Medium Voltage Distribution Networks And Line Channels

Medium voltage(MV)power channel planning is directly related to the safety,reliability and economy of medium voltage distribution networks.At present,the MV channel planning for many regions is often restricted by their own environmental conditions and local policies,which makes the channel resources scarce and the planning difficult.Therefore,the scientific and reasonable planning of medium voltage channels is particularly important.Nowadays,the channel planning research is mainly conducted by the two methods below: one is to carry out the network planning first and then the channel planning,the other is to consider the channel as a constraint condition in the distribution network planning.The former usually has the problems of channel infeasibility or insufficient channel capacity in engineering practice,so the network planning needs to be modified repeatedly;the latter takes the channel as a constraint,but the existing optimization model and algorithm are not practical and do not involve the channel planning and the related scheme testing.Firstly,based on the idea of coordination between MV channel planning and MV distribution network planning,the candidate channel networking which is related to channel paths and their capacities is determined and accordingly a power supply mesh networking is carried out.Secondly the target network planning is conducted and the corresponding network adjustment is carried out through the use of target network scheme testing.Then,based on the improved target network and existing network problems,the midterm network planning is carried out.Finally,the channel planning is performed based on the network planning schemes.For the candidate channel networking,according to the substation layout,the urban road planning and existing channels,the construction idea of candidate channel networking is proposed and the specific selection method of channel types is proposed based on the relevant channel construction standards,which involves the demand analysis of overhead and cable lines for the area adjacent to a substation,and the economic evaluation of building overhead lines first and then changing them into cable ones in new urban areas.As the key technology of large-scale MV distribution network optimization planning,a power supply mesh networking(i.e.,mesh division optimization)can make the scale of network planning from large to small and the corresponding method from complex to simple.From the purpose of engineering practice,the ideas and methods are put forward in this paper,which consider multiple factors,such as the land use type,power supply area type,development level,multi-specialties coordination and distributed generation.Based on the power supply area optimization division from the principle of loads’ “nearby backup supply”,the pre-processing and the post-processing methods are proposed for the constraints that are difficult to be dealt with.The pre-processing method is to integrate the other constraints(or factors)into the candidate channel networking by converting them into corresponding channel costs before the power supply area division is performed.The post-processing method is to first divide the power supply subareas according to the loads’ “nearby backup supply”principle and then reasonably adjust the division results in local scopes according to the other constraints,and the corresponding quantitative estimation formulas are given considering the influence of a single factor or multiple factors.For the network planning,the network planning schemes of target and midterm networks are performed respectively for each power supply mesh,and the related practicability testing of network planning schemes involves the proposed approximate power supply reliability evaluation model for the common channel lines of relevant outage.For the channel planning,the channel construction requirement and time sequence are respectively made clear according to the target network and the midterm network,and the specific ideas and methods of MV cable channel planning are proposed for the old and new urban areas.Compared with the traditional channel planning,the proposed coordinated planning method of MV(Voltage level of 10 k V and below)distribution networks and channels has stronger practicability and better economy,and can better solve many pain points that may be encountered in the actual planning.The examples show that the proposed model and method are effective and practical.