Energy-internet-based peer-to-peer energy trading and energy flow optimization

Abstract

Modern power system is undergoing a transformation from a centralized power grid to a decentralized smart grid due to the rapid penetration of distributed energy sources. The concept of Energy Internet (EI) is proposed as a new en­ergy system framework for future smart grid to facilitate peer-to-peer (P2P) en­ergy trading where all distributed electrical devices are interconnected via energy routers. Similar to the information Internet, Energy Internet is organized as a hierarchical power network, which consists of multiple energy local area networks (e-LANs). As the novel P2P energy trading requires a flexible end-to-end power delivery, each e-LAN adopts the technique of energy routing for traded power delivery, where the electrical energy is treated similar to a packet of mail and can be actively transmitted from the sender to the receiver. Under this context, the design of market clearing approach for P2P energy trading in EI becomes a chal­lenging task. Firstly, the designed market clearing approach should incorporate a proper energy routing algorithm which can achieve minimum-cost power trans­mission and eliminate possible path conflicts to ensure a normal operation of EI. In addition, each prosumer is allowed to make decisions independent of others in the designed market clearing approach so as to preserve prosumers’ privacy and respect prosumers’ self-interests. In this thesis, a two-tier market clearing approach with hierarchical network management is proposed for P2P energy trading in EI. In the proposed approach, a two-tier P2P energy market is promoted for EI, which is composed of an inter-area energy market and multiple intra-area energy markets. The network man­agement of EI is achieved by optimizing the energy paths within each e-LAN and the power flow between e-LANs in a hierarchical way. The first work of constructing the proposed market clearing framework is to establish the transmission cost model of energy routing in e-LAN. Due to the mathematical requirement of the proposed framework, the energy routing prob­lem is formulated as a convex optimization problem based on multi-path power transmission. A decentralized algorithm is proposed for the energy routing prob­lem to allow each trading pair to adjust their paths until their transmission costs cannot be further reduced. The resolutions for possible path conflicts caused by decentralized energy routing are discussed in a non-cooperative and cooperative way, respectively. Subsequently, a market clearing approach with cooperative energy routing is proposed for P2P energy trading within each e-LAN, which is divided into a decentralized market clearing stage and a cooperative energy routing stage. The decentralized market clearing stage aims to provide an open environment for prosumers to formulate their trading strategies. Any path conflicts caused by the decentralized market clearing are efficiently resolved by the cooperative energy routing stage. Furthermore, the intra-area market clearing approach is extended to a two-tier market clearing by considering an inter-area market. Each prosumer can participate in both the intra-area market in its e-LAN and the inter-area market. Unlike the intra-area markets, the inter-area market checks the feasibility of its outcome by analyzing the optimal power flow in wide area EI.