This paper presents a hybrid decoupled optimal power flow approach aimed at implementing an optimal power flow program for on-line applications. By taking advantage of the partial duality principle of mathematical programming theory and the inherent weak coupling characteristics between real and reactive power flows in a power system, the solution to the original optimization problem can be approximated iteratively by solving a real and a reactive subproblem alternately. Two special deliberately customized techniques, one based-on linear programming and the other based-on quadratic programming, are adopted to solve the two subproblems respectively. This hybrid feature makes the approach very flexible while preserving the efficiency of decoupling. The approach has been successfully implemented for on-line usage in the Control Center of Northeast China Electric Power Administration.
The research on land use and land cover changes is a core for studies on the global change. The study on spatial pattern and its change of land use is important for better understanding land use/land cover changes and environmental management.Remote sensing and geographical information system were used to analyze the landscape pattern and its driving factors of land use in China. First, the types of land use in China were divided into six major types and twenty-six sub-types. The major types include cultivated land, forestland, grassland, water area, built-up land and
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