Smart grids are being increasingly deployed worldwide, as they constitute the electricity grid of the future, providing bidirectional communication between households. One of their main potential applications is the peer-to-peer (P2P) energy trading market, which promises users better electricity prices and higher incentives to produce renewable energy. However, most P2P markets require users to submit energy bids/offers in advance, which cannot account for unexpected surpluses of energy consumption/production. Moreover, the fine-grained metering information used in calculating and settling bills/rewards is inherently sensitive and must be protected in conformity with existing privacy regulations. To address these issues, this report proposes a novel privacy-preserving billing and settlements protocol, PPBSP, for use in local energy markets with imperfect bid-offer fulfillment, which only uses homomorphically encrypted versions of the half-hourly user consumption data. PPBSP also supports various cost-sharing mechanisms among market participants, including two new and improved methods of proportionally redistributing the cost of maintaining the balance of the grid in a fair manner. An informal privacy analysis is performed, highlighting the privacy-enhancing characteristics of the protocol, which include metering data and bill confidentiality. PPBSP is also evaluated in terms of computation cost and communication overhead, demonstrating its efficiency and feasibility for markets with varying sizes.

翻译：智能电网作为未来电网的构成，正在全球范围内日益部署，为家庭用户提供双向通信。其潜在的主要应用之一是对等（P2P）能源交易市场，该市场有望为用户提供更优电价并激励可再生能源生产。然而，大多数P2P市场要求用户提前提交能源报价/出价，这无法应对意料之外的能耗/产能盈余。此外，用于计算和结算账单/奖励的细粒度计量信息本质上具有敏感性，必须根据现有隐私法规进行保护。为解决这些问题，本报告提出了一种新型隐私保护结算协议PPBSP，适用于不完善报价履行条件下的本地能源市场。该协议仅使用半小时间隔用户消费数据的同态加密版本。PPBSP还支持市场参与者之间的多种成本分摊机制，包括两种新的改进方法，以公平方式按比例重新分配维持电网平衡的成本。通过非正式隐私分析，凸显了该协议的隐私增强特性，包括计量数据与账单的机密性。此外，从计算开销和通信开销两方面对PPBSP进行了评估，证明了其在不同规模市场中的效率与可行性。