THE ABILITY OF MODERN TECHNOLOGIES TO INFLUENCE THE NEUTRAL MODE OF ELECTRIC GRIDS

Abstract

In this article, we consider the modes of neutrals of 0,38 to 750 kV networks. In any network with different voltage classes, the neutral point of a power transformer winding can operate both in isolated and deaf earthed mode. However, the choice of this mode depends on economic feasibility.
 The paper presents arguments and advantages of application of system with isolated and compensated neutral of networks with voltage classes 6–35 kV. For networks of these voltage classes various options of connecting arc suppression reactors with step and smooth regulation, as well as low and high impedance resistors in the neutral point of neutralizing transformer or zero sequence filter are considered. On the example of operation of electric networks of the Republic of Chuvashia for many decades it is emphasized that compensation of capacitive currents with arc suppression reactors is an effective and reliable way to protect not only substation electrical equipment from overvoltage, but also to ensure electrical safety of people and animals, as well as reinforced concrete towers from destruction.
 It is noted that the 6–35 kV networks in the future can be made with deaf earthed neutral. However, this will be possible under the condition that self-supporting insulated wires will be installed on overhead transmission lines instead of bare wires, and cross-linked polyethylene cables will be used on cable lines. It is emphasized that the introduction of work under voltage in 6-35 kV networks and digitalization of substations with the widespread introduction of microprocessor technology will accelerate the transition from a system with insulated (or compensated) neutral to a deaf earthed system. Nevertheless, the decision to switch from the insulated neutral system to a deaf earthed system will remain the prerogative of the design organization based on the specifics of the electrical equipment and the sphere of industrial activity.