Research on a New Single-End Fault Location Method for Single-Phase Grounding Faults of Transmission Lines Through Transition Resistance

A single-end fault location method for single-phase nonmetallic grounding faults of transmission lines in a double terminal system is studied and proposed. First, the reason for the poor accuracy of the single-end fault location method in case of single-phase nonmetallic grounding faults is analyzed theoretically, and the necessary conditions for the single-end accurate fault location are put forward. Second, under the necessary conditions of the single-end accurate fault location, according to the topology of fault component networks, the calculation method of the single-end accurate fault location of transmission lines in a double terminal system is studied. Moreover, the influence of line capacitance is considered in this fault location method, and a simple expression for calculating the fault distance is obtained. Finally, the transmission line with a single-phase nonmetallic grounding fault is modeled in PSCAD; therefore, the correctness and the ability against transition resistance of the new single-end fault location method are verified by simulation.

Determination Transition Resistance of Cathode-Polarized Main Pipeline on Magnetometery Data

The article deals with the inverse problem of determining the transient resistance of the main pipeline insulating coating. For this, UAV measurements of the magnetic induction vector modulus of the magnetic field excited by the system of electrochemical cathodic protection of pipelines are used. The solution method is based on Tikhonov's method for finding the extremal of the regularizing functional. The developed algorithm is implemented in software. The results of computational experiments are presented.

A novel current differential protection for MMC-HVDC lines

The present current differential protection for MMC-HVDC transmission lines has absolute selectivity and powerful ability to withstand high transition resistance, while it is easily affected by distributed capacitive current and data synchronization error. To solve the problem above, this article proposes a novel current differential protection scheme. The distributed capacitive current can be calculated by integrating the linear voltage distribution in real-time. Thus, the differential value of the midpoint currents of DC line, which are calculated based on the low-pass filtered measure voltages and currents on both sides, can be adopted to identify the fault. Besides, the data synchronization error can be eliminated based on the waveform matching of the calculated midpoint currents. This novel current differential protection has excellent performance and can solve the problems of traditional current differential protection for HVDC lines.

ENERGY SAVING TECHNOLOGIES IN THE IMPLEMENTATION OF CATHODIC PROTECTION OF PIPELINES AND TANKS

The data on the introduction of new energy-saving technologies of cathodic protection – the installation of magnetite ground electrodes, the use of new activators based on coke breeze, a pulse converter for automatic control of cathodic protection objects are considered. Practical results show that the use of magnetite anodes allows maintaining a high permissible current density, therefore, it is suitable for widespread use in various soils and seawater. The rate of dissolution of magnetite is 0.02 kg / (A • year). Magnetite anodes are also successfully used for the repair of GAZ wells (deep earthing conductors made of metal pipes). To perform this type of work, a typical project has been developed, which allows restoring the operability of deep anode grounding with minimal costs and without the use of expensive drilling operations. The use of activated coke breeze significantly reduces the transition resistance of the anode grounding. It has been practically proven that when using a coke-mineral activator, the transition resistance is significantly reduced due to an increase in the electrical conductivity of the filler at the anode space, the geometric dimensions and current of the diverting object increase, and the transition resistance of the anode - ground is stabilized. LLC "Elmet" has developed a pulse converter of automatic control IPAU designed to convert alternating current into rectified direct current with the possibility of automatic adjustments in several parameters. The basis of the converters is a high-frequency transistor inverter, developed on the basis of the latest achievements in power electronics. The use of stations of the IPAU type with telemetry allows to reduce labor costs for their maintenance in accordance with clause R.6.1 DSTU B V.2.5-29: 2006 Gas supply system. Underground steel gas pipelines and p. 8.9 of DSTU 4219: 2003 Steel main pipelines, which will make it possible to use the freed up personnel in other areas.

A novel fault section locating method based on distance matching degree in distribution network

Fault section location of a single-phase grounding fault is affected by the neutral grounding mode of the system, transition resistance, and the blind zone. A fault section locating method based on an amplitude feature and an intelligent distance algorithm is proposed to eliminate the influence of the above factors. By analyzing and comparing the amplitude characteristics of the zero-sequence current transient components at both ends of the healthy section and the faulty section, a distance algorithm with strong abnormal data immune capability is introduced in this paper. The matching degree of the amplitude characteristics at both ends of the feeder section are used as the criterion and by comparing with the set threshold, the faulty section is effectively determined. Finally, simulations using Matlab/Simulink and PSCAD/EMTDC show that the proposed section locating method can locate the faulty section accurately, and is not affected by grounding mode, grounding resistance, or the blind zone.

Reduction of the transition resistance of demountable contact joints using gallium alloys

The article studies the possibility of reducing the transition resistance of demountable electrical contact joints in laboratory conditions by using multicomponent gallium alloys. The relevance of the chosen topic is attributed to the need for reducing energy losses and improve the reliability of a contact network.

Development of Calculation Model of the Distribution of Protective Currents of Gas Pipeline Electrochemical Protection System in Permafrost Soils

Clarification of parameters of the distribution of protective currents in permafrost soils is an urgent issue. The article describes a grid model of the soil, which differs from the generally accepted homogeneous model. Grid model of soil imitates various conditions of permafrost. Calculation model allows us to estimate parameters of the electrochemical protection of gas pipelines, taking into account the inequality of the parameters of the electrical conductivity of soils and also the transition resistance of the protective coating of the pipes along the length of the section. The model also makes it possible to estimate seasonal changes in the propagation conditions of protection currents due to periodic thawing and freezing of the soil in the conduction layer.