Active Distribution Grid Power Flow Analysis using Asymmetrical Hybrid Technique

A conventional distribution power flow analysis has to be improved regards the changes in distribution network. One of the changes is a grid operation because a new grid concept, e.g. micro-grid and aggregation, is aimed to be operated based on area itself. Consequently, each area can be actively operated in either grid connected mode or islanding mode. Hence, this paper proposes an asymmetrical power flow analysis using hybrid technique to support this flexible mode change. The hybrid technique offers an opportunity to analyze power flow in a decoupling way. This means that the power flow analysis can be performed separately in each grid area. Regards the distributed generation, this paper also introduces a model based on inverter-based operation, i.e. grid forming, grid supporting and grid parallel. The proposed asymmetrical hybrid load flow method is examined in three case studies, i.e. a verification study with the DIgSILENT PowerFactory, a demonstration of decoupling analysis approach and a performance study with the Newton-Raphson method

Frequency regulation service of multiple-areas vehicle to grid application in hierarchical control architecture

Regarding a potential of electric vehicles, it has been widely discussed that the electric vehicle can be participated in electricity ancillary services. Among the ancillary service products, the system frequency regulation is often considered. However, the participation in this service has to be conformed to the hierarchical frequency control architecture. Therefore, the vehicle to grid (V2G) application in this article is proposed in the term of multiple-areas of operation. The multiple-areas in this article are concerned as parking areas, which the parking areas can be implied as a V2G operator. From that, V2G operator can obtain the control signal from hierarchical control architecture for power sharing purpose. A power sharing concept between areas is fulfilled by a proposed adaptive droop factor based on battery state of charge and available capacity of parking area. A nonlinear multiplier factor is used for the droop adaptation. An available capacity is also applied as a limitation for the V2G operation. The available capacity is analyzed through a stochastic character. As the V2G application has to be cooperated with the hierarchical control functions, i.e. primary control and secondary control, then the effect of V2G on hierarchical control functions is investigated and discussed

Evaluation of lightweight battery management system with field test of electric bus in campus transit system

A battery management system is a crucial part of a battery-powered electric vehicle, which functions as a monitoring system, state estimation, and protection for the vehicle. Among these functions, the state estimation, i.e., state of charge and remaining battery life estimation, is widely researched in order to find an accuracy estimation methodology. Most of the recent researches are based on the study of the battery cell level and the complex algorithm. In practice, there is a statement that the method should be simple and robust. Therefore, this research work is focused on the study of lightweight methodology for state estimation based on the battery pack. The discrete Coulomb counting method and the data-driven approach, based on the Palmgren-Miner method, are proposed for the estimation of the state of charge and remaining battery life, respectively. The proposed methods are evaluated through a battery-powered electric bus under real scenario-based circumstances in the campus transit system. In addition, the battery life-cycle cost analysis is also investigated. The tested bus has currently been in operation in the transit system for more than one year

Management strategy for SmartGrid - A cluster system analysis method

Recently, Distributed Generation (DG) technologies become more potential in electricity supply contributors to electric utilities. It leads to increase the grid integration ratio of DG. Thus, the trend of decentralized power systems has been considered as a future of energy supply systems. According to this fact, the distribution systems must be changed from a passive control area to be an active control area. To overcome and realize this issue, the clustering power systems approach is developed. The main idea of this concept is to coexist the DG with the conventional power systems. Therefore, the system structure and the control approach are introduced and developed based on the conventional system. The cluster network structure keeps the main idea of conventional interconnected grid. Consequently, the clustering power systems concept intends to cluster the power systems into several areas, called cluster area. As a direct result, the cluster network structure can be described like the interconnected grids. In order to empower and turn the ordinary passive distribution system to be the active system, the clustering approach announces the distribution management system (DMS) for the cluster automation application. The DMS application is the cluster controller and management, which applies in each cluster area. To accomplish the DMS functionality, control functions based on cluster concept have been developed continuously, e.g. the multi-level clusters control approach. Besides the development of cluster control approach, a cluster analysis strategy is cautiously considered as well, since it is a key to complete a cluster management and an optimization process. A hybrid calculation technique is consequently proposed to be a solution for cluster analysis, because it offers a possibility to integrate a character of interconnected clusters into the analysis. Hence, the cluster analysis can be employed in a decoupling way. To evolve the cluster analysis, a character of distribution network has to be taken into account. The character of distribution network is dominated by the unbalanced condition e.g. multi-phase feeder system. Moreover, the penetration of DG units can cause unbalanced condition as well, e.g. single phase feed in of home PV systems. To deal with unbalanced condition, an asymmetrical sequence hybrid and asymmetrical three-phase fourwire hybrid analysis method is rolled out, both are developed based on a difference issue of load flow studies. All in all, the cluster analysis is a key to execute optimization and management process of cluster system operation as well as the supervisory of automated cluster control application. Finally, the proposed hybrid analysis is ready to be the main function in order to ensure and forwards the development of clustering power systems philosophy to be one of the best solutions for the future smart gird applications