Hybrid Wind Power Plants

Combination of conventional engine power plants in island grids with wind power is one way to improve the economical and environmental performance of the power sys-tem. Hybrid wind-diesel systems with high wind penetration have been at the experi-mental stage for a couple of decades, but they have not been held for an economic choice until these days. In the size range below 1.5 MW, some manufacturers offer commercial systems, but larger hybrid systems still seem to be an unoccupied market. The aim of this thesis is firstly to clarify today’s situation in the wind power market, which techniques are state-of-the-art and which solutions would be suitable for a hybrid system. Also the reciprocating engine technology, both for operation on gas and oil, will be shortly reviewed and examined in order to determine which engine models could preferably be used in combination with wind power. Secondly, the power system re-quirements and the particular characteristics of hybrid power plants will be investigated. It is very challenging to achieve a deep understanding of the transient performance of a hybrid power system, which is needed to determine both the need and dimensioning of different equipment. From the author’s point of view, the only way to get this under-standing is by simulation of the whole system. Therefore, the simulation part is consid-ered the core of this study and is given plenty of space. The simulations are made with Matlab® Simulink® based on time series of wind and load data. Different concepts with different levels of wind penetration are simulated in order to determine to which extent different equipment need to be included in a hybrid system. Since no real wind data with high enough resolution was available, synthetic wind data was used. Consequently, it is hard to give any general statement about feasibility and need for equipment based on the results. On the other hand, wind and load characteris-tics differ from site to site and the appropriateness of the data is not crucial for the un-derstanding of the system. A conclusion that can be made from the simulation results is that the power ramp rates are more challenging than the frequency stability. One or sev-eral of the discussed strategies needs to be applied when the wind penetration level is raised. A major contribution of this study is the simulation model as such, which can be used in the preliminary design of a hybrid power system when a real project actualizes.