The digital transformation of power systems necessitates robust solutions for data security challenges, such as provenance verification, tamper resistance, and privacy compliance. This research proposes a novel blockchain-based architecture integrated with threshold proxy re-encryption (TPRE) to establish a trustworthy electricity data ecosystem. The framework transforms grid devices and organizational units into permissioned blockchain nodes, creating an immutable ledger for endto-end data provenance while preventing unauthorized modifications. Regulatory entities gain granular traceability capabilities to audit data flows and pinpoint anomalous nodes with cryptographic certainty. To address the dual requirements of multi-party data sharing and privacy protection in smart grid environments, we implement an optimized TPRE scheme that significantly reduces computational overhead compared to conventional approaches. Our solution enables secure delegation of re-encryption rights while maintaining threshold-based access control over sensitive power consumption data. Experimental results demonstrate that the proposed scheme reduces computational overhead by 33.3% under multiuser scenarios compared to conventional proxy re-encryption methods, while enhancing key randomness through threshold-based secret sharing. The proposed framework offers practical insights for implementing cryptographically secure, regulator-compliant data management systems in critical energy infrastructure.