Medium/Long Term Load Forecasting For Power System

Load forecasting for power system is one of the important task of power utilities. Accurate load forecasting is helpful to planning generators" starting and stopping in the interior of the electrical networks economically and reasonably, preserving the security and stability of power system, reducing the unnecessary circumvolving repertory capacity, making planning to overhaul the units in reason, ensuring the normal production and life of the society, effectively reducing the cost of generating electricity, increasing the economical and social benefit. Long term load forecasting is commonly to be forecasting which is more than ten years and uses year as it's unit, and medium load forecasting is commonly to be forecasting which is about five years and uses year as it's unit too. They are helpful to planning new generators (including the generators' capacity, type, address and time), designing, building and rebuilding the electrical networks. They are the most important jobs of the power planning utilities.After discussing the constituents and characteristics of the electric load, analyzing and comparing the merits and shortcomings of some forecasting methords, the paper chooses the hybrid method, grey model and linear regression, to build the medium/long term load forecasting model, which separates the forecasting job into two parts: one is using grey model to forecast the correlative factors and the other is using linear regression to forecast the loads. It can take full advantage of the grey model, which requires few data, doesn't consider the distribution rule and changing trend, has convenient operation, checks up easily, and so on. It can also make the bestof linear regression, which can consider factors influencing loads, use mature technology to estimate model parameters, easily forecast loads.After discussing the hybrid forecasting method, the author uses it to forecast the loads of the Meishan city, Sichuan province. The utility proves its feasibility.In the end, the paper discusses the merits and shortcomings of the method and the improvement of medium/long term load forecasting methods for the new situation under power market.