Abstract:
Single-phase access to intermittent household new energy and vehicle charging piles exacerbates the problem of three-phase imbalance in station areas. The significant number of stations and load randomness lead to the complex identification of imbalanced stations and colossal human and material costs for imbalance management. To reduce the cost and improve the management effect, this paper proposes the dominant imbalance degree assessment of any selected period (e.g., the day before yesterday) and the optimization method of dominant-phase component balancing to screen out the severely imbalanced station areas and get the inter-phase load transfer scheme. It is found that the time series matrix of the three-phase currents of the total table of the station is decomposed by singular values and the dominant array is the main component of the original matrix; The unique dominant imbalance degree, the direction of interphase transfers and the dominant component share in any chosen period can be characterized by its left singularity vector; according to the time series characteristics of the suitable singular vector, the dominant and the secondary components of each single-phase load of the heavy-loaded phase can be extracted. Therefore, the optimization to balance the dominant phase components and offset the secondary phase components can avoid the catastrophic computation volume of random combination optimization and obtain a practical scheme for the single-phase load combination of inter-phase transfer. The arithmetic example verifies the effectiveness of the proposed method. The idea of this paper does not pursue the accuracy of each moment but aims to seek the overall optimality of any selected period; the proposed method of identifying and managing the severely unbalanced station area has good feasibility and is of practical significance for improving the power supply quality and equipment safety of the distribution network.