Source: Faculty of Infrastructure Engineering

By Li Xiang, Cheng Chuntian

Recently, Prof. Cheng Chuntian’s team from Institute of Hydropower & Hydroinformatics of DUT published an important work entitled A MILP based Framework for the Hydro Unit Commitment Considering Irregular Forbidden Zone Related Constraintson IEEE Transactions on power systems, which is a top journal of power systems (DOI:10.1109/TPWRS.2020.3028480).

The irregular forbidden zone(FZ) is a common phenomenon with giant hydropower plants developed in the past two decades in China. Irregular shapes of FZs significantly challenge hydro unit commitment (HUC). The work of Prof. Cheng’s team proposes a novel MILP based framework for HUC considering irregular FZ related constraints including the FZ constraint, effects of linearization errors in both the net head and the output, and the FZ crossing constraint. In the framework, the FZ constraint is handled by the optimal convex partitioning algorithm and the common structure-based formulation method. Inspired by the planar translating robot placement problem, linearization errors are considered by the Minkowski sum method. To handle the FZ crossing constraint, they then propose a graph theory-based approximate formulation method. The framework is integrated into a HUC model with an objective of peak shaving. The model is then tested with a batch of real-world instances of a cascade hydropower system formed by ten giant units with highly irregular FZs. The results show their framework can effectively consider the irregular FZ related constraints. The major advantage of their framework is its ability to handle the irregular shapes of FZs without any tedious and error-prone manual processing.

In 2008, during the process of developing the advanced water dispatching application software for China Southern Power Grid, Prof. Cheng’s team was the first to discover the problem of forbidden zones in Tianshengqiao First Cascade and Second Cascade Hydropower Stations, which is a very thorny issue for power grids and power generation enterprises. It was founded that the same problem also exists widely in world’s top 20 hydropower stations, such as Xiluodu station, Xiaowan station, Longtan station and Nuozhadu station. For more than a decade, the team has been committed to solving this problem in terms of both fundamental theory and engineering implementation technology, and this paper is a summary of the latest research results, which is supported by the National Natural Science Foundation of China.

Photo: Zhao Zhipeng

Editor: Li Xiang