At Novosibirsk State Technical University (NETI) proposed a solution to one of the urgent problems of the development of the electric power industry — reliable operation of 6-110 kV high-voltage electric networks with small generation distributed over the network from 1 to 25 MW (active distribution networks). For this purpose, a comprehensive emergency management method has been developed and patented for the selective shutdown of damaged power lines and decentralized automatic restoration of the network after its emergency or emergency separation. The introduction of this method will provide consumers with affordable energy with high reliability of energy supply. The work was carried out with the support of the Ministry of Education and Science of the Russian Federation under the program "Priority 2030" of the national project "Science and Universities".
The development of active distribution networks (ARES) is due to a number of reasons, among them are the desire of many energy consumers to reduce dependence on centralized energy supply, the economic benefit of using their own energy sources, high reliability of power supply provided they work in a common network and a very important factor at present — survivability under unpredictable and strong external disturbing influences, for example, short circuits.
"The problem was as follows: the transformation of passive distribution networks into active ones sharply complicated the solution of the problem of detecting the occurrence of short circuits in power transmission lines by means of relay protection in conditions of multilateral supply of lines from distributed energy sources. The use of expensive, so-called remote protections, common in 110 kV and higher networks, is economically unacceptable for mass power transmission lines of distribution networks. Emergency shutdown of generators operating in the network in case of short circuits is unacceptable due to the occurrence of unacceptable surges active power in the network with a high probability of subsequent accidents. In addition, restoring the integrity of the network and the normal power supply to consumers would require the creation of a system of automatic and centralized operational management of the distribution network, which is also economically unjustified. The use of commonly used devices for automatic re—activation of power line switches to restore the network becomes unacceptable due to the possibility of switching on switches with unsynchronized alternating current sources operating on both sides, which creates an emergency situation," said Alexander Fishov, Professor of the Department of Automated Electric Power Systems at NSTU-NETI, Doctor of Technical Sciences.
The proposed solution consists in a decentralized multi-stage management, including: quick and easy identification (upon emergency voltage reduction) of the network area, inside which the short circuit is guaranteed to occur; express disconnection from the generator network while maintaining power supply to some consumers; disconnection of power transmission lines and their subsequent specially organized re-activation, eliminating the possibility of unsychronized inclusions sources on the network. To do this, a single time clock is introduced for all network switches, within which each switch has its own unique time quantum. In this case, local devices issue commands to turn on the switch if voltage is applied to the switch from only one side or if the voltages supplied from both sides of the switch are normal and synchronized. If a short circuit is detected when the line is switched on again, it is switched off for subsequent operational or repair maintenance.
"The proposed method solves the problem presented above, allowing the development of active electric networks based on previously existing passive ones in an economically justified way, providing consumers with affordable energy with high reliability of energy supply," added Alexander Fishov.
