25 июня 2018
«ЭЛЕКТРОЭНЕРГИЯ. Передача и распределение» № 3(48), май-июнь 2018
ТЕЛЕКОММУНИКАЦИИ И СВЯЗЬ
ЭЛЕКТРИЧЕСКИЕ СЕТИ 20 КВ
ДИАГНОСТИКА И МОНИТОРИНГ
ПУТЕШЕСТВИЕ В ПРОШЛОЕ
The paper considers modern FACTS technologies and their application in modern electric power systems, including the Unified National Power Grid of Russia.
Abstract. The paper considers the estimation of consumer impact on voltage unbalance and unsinusoidality in electric network. Impossibility to correctly identify the certain consumer contribution to
-th harmonic voltage or negative sequence voltage in network node is shown. A method for estimating the consumer impact on voltage distortion using individual consumer characteristics of distortion voltage is proposed. Methods for preliminary processing of measured currents and voltages are developed. Those methods allow to determine afore-mentioned consumer characteristics in real time without special switching in electric network. The results of an experimental evaluation of real electric loads impact on voltage unsinusoidality are presented.
The paper considers rational construction of distribution electric networks schemes for modern megacities in the context of reliability enhancement. The loads growth, increased requirements to power supply reliability and special features of transition from rated voltage 10 kV to 20 kV are considered. The paper also analysis changes in the construction of power distribution scheme, composition and parameters of used electrical equipment and shortcomings of existing open-loop network (such as loop and biradial power supply schemes) built on a single-link and two-link principle. The paper provides recommendations related to organization of 20 kV networks operation (with regard to relay protection and automation), implementation of 20 kV networks with enhanced reliability, as well as information on the progressive trend of distribution network digitalization.
The paper considers thermal regime of a three-phase cable line laid in a narrow polymer pipe. A numerical model concerning conductive, convective and radiant heat exchange in the cable line was developed. The model was verified by comparing simulation results with experimental findings related to thermal regime of the cable line. Correction coefficients regarding all the heat exchange mechanisms in a simplified solid model were determined. Those coefficients are suitable for express engineering calculations.
In the article the new method (patent pending) for the selective AR implementation on the HV and EHV power lines of different configuration is proposed. The method is applicable for different OCL configurations: the cable part or parts can be located on the several distances from the substation (relay protection and AR location), cable parts can have different types of shield grounding (one or several point shield groundings with or without shield transposition) etc. The proposed selective AR system can be centralized or decentralized depending on the OCL configuration and based on the direct/indirect cable shield current determination and comparison. The method uses the latest achievements in photonic. The proposed principle of cable fault determination on OCL investigation results by means of simulation models and the selective AR prototype device test results by means of RTDS are presented. At the moment selective AR prototype device is putting into the operation on the 500 kV OCL with several cable parts in Moscow region.
The accident-free functioning of distribution networks of power supply systems with a deadly neutral to 1000 V depends largely on the frequency of single-phase short-circuits (SC), which are the most common type of insulation damage. The article presents the concept of a system for monitoring and diagnosing the state of isolation of electric grids with a deadly grounded neutral, which makes it possible to move from the fight against the consequences of insulation violations to their prevention and, as a result, to significantly increase their electrical fire safety.
Innovative developments of transformer and reactor equipment are described. The equipment provides energy efficiency, fire and explosion safety and reliability of nuclear power plants electrical equipment.
In accordance with the orders No. 968 dated October 16, 2017 and No. 1196 dated December 20, 2017 promulgated by the Minister of Energy of the Russian Federation A.V. Novak, the necessary changes have been made to the existing wiring regulations. From now on modernized aluminum alloys No. 8030 and No. 8076 have been returned for electrical wiring application in residential and public buildings. In appendix to the order, the types of networks and the conditions for new cables application are contained. This paper considers the results of the research carried out at FGBU VNIIPO of EMERCOM of Russia, which contributed to the appearance of afore- mentioned orders.
The paper considers and systematizes the basic requirements for safety ensuring in operation under induced voltage. Approach to formation a list of overhead lines under induced voltages in accordance with “Rules for labor protection when operating electrical installations” is considered. Recommendations providing safe work on deenergized overhead lines under induced voltage are given. Reasons of induced voltage occurrence, mechanism of its formation, its components and reduction measures are considered.