Lijie Xu

Application of single-phase three-wire transformer model in distribution network with solar home system

As solar home systems are concentrated in distribution network in residential areas, the voltage of connection points rises according to the reverse power flow when the demand of load is less than power generation out-put. When single- phase three-wire power distribution transformer (method) is applied to low-voltage distribution network, power flow calculation becomes the major approach to perform quantitative analysis. We looked for a method of analysis in which the high-voltage systems and the low-voltage single-phase three-wire systems are unified for calculating power flow. The first step is setting up a single-phase three-wire transformer model. This paper presents a new model of single-phase three-wire transformer using the indication method between nodes. Meanwhile this paper also gives the models nodal transform matrix for calculating power flow. Using this model we can solve the problem of power flow calculation by using conventional power- flow-calculation methods when high-voltage and low-voltage with single-phase three-wire distribution systems are intermingled. The results also can reflect the voltage characteristics of connection points when injecting effective power into node from solar home systems. Using this new model we computed an example and analyzed the result. When solar home systems are connected in single-phase three-wire low-voltage distribution network, changing the power generation out-put, the voltage characteristics of connection points are consistent with theoretical analyses. The example shows that the model is feasible for calculating power flow of low-voltage single-phase three-wire systems with solar home system.

Security Impacts and Key Issues of Integration of REGs on Distribution System

With the permeability of the renewable energy generations (REGs) becoming greater, the distribution network (DN) has become a complex interconnected network with distributed generations (DGs) and loads from a traditional radiate one. REGs bring the great opportunity to low-carbon and sustainable development of the distribution system (DS), but it also brings severe impacts to the security and stability of the operation. In this chapter, six key impacts regarding secure operation are analyzed including power transmission, power quality, frequency stability, islanding effects, protection, and power-system planning. Based on the analyses, corresponding suggestions are introduced. Particularly, the promotion of REGs’ stability and controllability, as well as the coordinated planning method for DN considering the integration of REGs, are discussed in detail.

An overview of applications of MAS in smart distribution network with DG

The field of Multi-agent system (MAS) is an area increasingly studied. With advantages of autonomy, collaboration and reactivity, MAS has been widely used in smart distribution network. This paper summarizes the main applications of MAS in smart distribution network, including micro-grid energy management and coordination, protection system of distribution network, condition monitoring and fault diagnosis, and power market and so on, especially focused on the MAS-based micro-grid energy management and coordination, and the protection system of distribution network. With the use of MAS, micro-grid energy coordinated control strategy under islanding mode and control system framework are proposed. At last, this paper discusses the technology challenges and prospects of MAS in smart distribution network.