Xing Deng

Study of the operation of parallel cables

Due to the manifest electromagnetic coupling effect, parallel cables cause couples of problems to its operation safety and management. The present paper describes the questions brought by parallel cables from the following three aspects: influence on parameter asymmetry, influence on induced voltage in metal shield of cables and influence on distance protection. This paper analyzes the parameter asymmetry of several typical arrangements for parallel cables comparatively. The influence of phase distance and arrangement of cables on induced voltage in metal shield of cables is also illustrated. In the end, the operating characteristic of distance protection are studied in the specific project.

Calculation of induced voltage in metal shield of single-core cable operated in parallel

The present paper proposes a method for calculating induced voltage in the shield of single-core cable with the basic theory of electromagnetic field. With this method, the induced voltage in metal shield of single-core cables operated in multi-circuit can be calculated. Take cables operated in double-circuit as an example, the influence of phase distance and arrangement of cables on induced voltage is analyzed. On this base, paper suggests proper phase distance and arrangement of cables should be chosen to reduce the induced voltage in metal shield.

Wide-Area Backup Protection Algorithm Based on Multisource Information Fusion

Wide-area backup protection is a novel technique presented in recent years, which uses multisource information to make fault identification decision and availably prevents catastrophic blackouts. However, the property of algorithm will be deteriorated when information error exists. For the sake of improving the property of wide-area backup protection, this paper proposes an information fusion strategy using genetic algorithm to optimize the decision-making function. The operation information from local directional pilot relay and impedance relay is applied to establish the fitness function. Simulation tests based on IEEE 3-generator and 9-bus system validates the presented algorithm under as many as 3 bits information error.

Study on Unbalance Factor of Sequence Impedance for Parallel Multi-circuit Cable Lines

Parallel multi-circuit cable lines are wildly used to improve the transmission capacity of urban power grid, but the study on sequence impedance parameters’ asymmetry of multi-circuit cable lines is not available. To analyze the asymmetry of multi-circuit cable lines’ parameters, a method to measure the unbalance factor is introduced in this paper. Furthermore, take engineering practice as an example, the electromagnetic unbalance factor of two-circuit cable lines under different arrangements are calculated by this method. Finally, a comparison among these unbalance factor is made. The comparative results show that the triangle arrangement has better symmetry than straight-vertical and straight-horizontal arrangement, in which the triangle-vertical arrangement’s symmetry is the best.