Blockchain applications for peer-to-peer energy trading

• Main Author: Yang, Jiawei
• Other Authors: Gooi Hoay Beng
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/166538
• Institution: Nanyang Technological University

Peer-to-peer (P2P) energy trading is emerging as an increasingly popular approach because prosumers are allowed to trade their energy directly without intermediaries. This decentralised trading structure could be matched with the blockchain function to provide a more robust cyber-physical system as the blockchain is able to ensure the integrity of the transaction data and the privacy of prosumers. Since the consensus protocol of the blockchain determines its usage, a proper blockchain type and an effective pricing scheme design are required to safeguard the energy trading and improve the social welfare of the microgrid. In addition, a stable power delivery system is significant as it supports the energy trading. Therefore, the control system of the microgrid should also be safeguarded against any cyber attacks such as false data injection (FDI). The cryptographic mechanism and distributed ledger recording function enable the blockchain to provide a comprehensive protection for both P2P energy trading and control system. With the support of the smart contracts, designing a proper pricing scheme for energy trading and ensuring the security of the distributed secondary control for the frequency of the microgrid is a challenging task. This thesis presents the study of the blockchain application in two different power system domain, including the energy trading and power system control. The focus of the thesis is to develop a comprehensive blockchain adaption for pricing scheme design and distributed control. The combination of their respective blockchain is achieved by the setup of the cross-chain smart contract communication functions provided by the Geth software. The contributions of this thesis are threefold: The first part proposes a Proof-of-Stake (PoS) blockchain based pricing scheme for p2p energy trading. Miners sacrifice part of their stake to compensate for the power losses and reduce the price gap from the traditional prosumer-to-grid trading. The proposed model also contributes to increase the social welfare by improving producers' income and consumers' cost-saving through the designed pricing scheme, which eliminates the price gap between buying and selling. Successful mining is encouraged by rewards accordingly. The proposed method is applied to a 27 nodes-microgrid with photovoltaic (PV) and energy storage systems and its results prove the feasibility and effectiveness of the proposed method. The second part proposes a Proof-of-Authority (PoA) blockchain based distributed control system for islanded microgrids to secure each distributed control process and cause no negative effects on the quality of control results. The block production rate of the proposed blockchain is technically updated to match with the control layer. Smart contracts are created to calculate the control feedback and return the value to corresponding secondary controllers. All of the distributed generation (DG) nodes are initially assigned as the authority nodes to share the mining burden, but according to the PoA protocol, the authority role could be excluded if the node behaves illegally and causes damage to the control system. In addition, four attacking scenarios that could possibly damage the frequency restoration are analyzed with their respective solutions provided by the proposed blockchain model. The effectiveness of the proposed approach are proved via the illustrative case studies. The final parts presents a hierarchical blockchain system for both distributed control and energy trading within a microgrid range. The security of both layers of the microgrid is ensured. Smart contracts are created to calculate the feedback measurements for the control system and execute the energy transactions. According to the hierarchical structure, the private blockchain with static nodes is implemented for the distributed control to match the sampling rate and safeguard the control system against FDI attacks. A PoA based blockchain is utilised to support the P2P energy trading to fulfill consumers' energy demand by transferring extra energy of producers. A double auction based simple iteration (DA-SI) pricing scheme is designed to generate the optimal trading price for the microgrid prosumers to save their trading cost and improve the social welfare of the whole microgrid. The proposed method is verified via the illustrative case studies.