Variable-Speed Hydropower Generation: System Modeling, Optimal Control, and Experimental Validation
Jian Gao, Litao Dai, Xiao Liu, Xudong Du, Derong Luo, Shoudao Huang
Abstract
The variable-speed hydropower generation technology of small hydropower plants has great potential because of abundant water resources and the low overall efficiency of the traditional constant speed plants. In this article, we investigate a converter-fed synchronous generator system capable of variable-speed operation (VSO) in the full power range. First, the hydraulic turbine, permanent magnet synchronous generator, and power electronic converter in the system are modeled, respectively. Next, based on the system model, a three-layer control system is proposed to realize the multiobjective control. To automatically track the optimal speed under different inflow rates, a modified “perturb and observe” algorithm is proposed, which is easy to implement and able to track the maximum power point quickly and accurately compared with the classical method. In addition, the proposed system is used to reconstruct one of the two parallel hydropower sets with the same hydrological conditions. And the performance tests and comparative experiments between the fixed-speed operation and VSO sets were extensively performed. It shows that a considerable increase in energy production is achieved in the VSO set.