The introduction of incentive regulation principles in tariff setting is based on a significant (many times) reduction in basic indicators such as ENS and SAIDI. An analysis of the dynamics of ENS and SAIDI abroad shows that the reduction in the value of SAIDI is characterized by a threefold decrease every third of the time period from the moment the incentive regulation was adopted to the present day.
In leading countries, such a program has been implemented for 30-40 years and the SAIDI value does not exceed 100 minutes per year. The figure declared in domestic networks, according to various sources, lies in the range of 600-900 minutes per year. At the same time, analysis of reliability indicators of networks using the principles of decentralized sectioning for 15 years has proven the effectiveness of using reclosers as the main equipment when creating automatic sectioning and network backup points, based on reducing the time to search for an accident site and reducing the time to restore power supply to the end consumer. In domestic networks, the most widespread is the so-called “targeted” increase in reliability, which makes it possible to significantly reduce SAIDI as the main indicator used to assess the reliability of the SAIDI distribution network. As an example, it is proposed to analyze a real 10 kV feeder circuit and the performance indicators of this network, the basic circuit of which is shown in Picture 1.
The basic scheme is characterized by the following indicators: specific damage rate ω0=69 1/year (according to the operational log), length L=20.29 km, installed power P=4.7 MVA, average recovery time Tv=5.6 hours. The calculation method allows us to determine the calculated value SAIDI = 1996 min and the undersupply of electricity Wbase = 8534 kVA.
The network modernization project provided for the organization of network redundancy of TP-876 with partial replacement of the overhead line with a cable line, as well as the implementation of parallel sectioning of two branches. As a result of the implementation of this project, the design scheme acquired the form shown in Picture 2.
Taking the load factor of the installed equipment at 0.5, we determine the values of SAIDI and ENS.
For branches from the main line (parallel sectioning), the SAIDI value was 593 minutes, which is almost 4 times less than the same indicator for the base case.
For consumers powered from a network backup point, the SAIDI value is improved by almost 40 times and amounts to 55 minutes. The undersupply of electricity by the network company to consumers supplied from branches was reduced by 14 times and amounted to 1830 kWh. The undersupply of electricity to consumers powered by a network ATS is not critical under these conditions.
Thus, the implementation of network ATS using vacuum reclosers can significantly improve the reliability characteristics of the network. It should be noted that in this case, the undersupply of electricity to consumers powered by a network ATS is not decisive and may not be used when assessing the economic feasibility of such projects due to the greater significance of the SAIDI value.