The concept of Virtual Power Plant (VPP) has become an attractive solution to optimize the integration of renewable energy sources into the grid. However, the operation and transaction system of VPPs still face several challenges, such as the lack of transparency, security, and efficiency. In this learning, we propose a new operation and transaction system built on blockchain technology for VPPs. The proposed system contains of two layers, the blockchain layer and the application layer. The blockchain layer is responsible for ensuring the security and transparency of transactions, while the application layer provides an interface for VPP operators and users. We implemented the proposed system using Ethereum, one of the most popular blockchain platforms. We also conducted a case study to evaluate the routine of the proposed system in terms of transaction throughput, latency, and scalability. The outcomes show that the proposed system can handle a large quantity of transactions with low latency and high scalability. Our study demonstrates the possible of blockchain technology to enhance the operation and transaction system of VPPs, which can contribute to the integration of renewable energy bases into the grid.