Up to now, there are insufficiencies in most methods for optimal reactive power planning considering multi-load levels, such as relative complexity in calculation and hard to use in practice.

Firstly, based on a tracing algorithm, the system SSSR under specified load level is calculated, which is a closed region composed of four Hopf bifurcation carves.

The method divides one day into several sections according to the total load or same bigger load level, its changing trend and the maximum allowable number of tap changer operations, then performs reactive power optimization separately, at last, d.

Electric power forecasting based on average load method;

By means of force analysis of shearer helical drum,mathematical models of average loads on a shearer's helical drum are set up in the paper,the average load carries out the computer simulation on helix drum,the simulation curve reflects drum load and with being unlike parametric change,being that helix drum design lays down basis thereby.