## 2 Knowledge and Tools of Model Preparation
The result shows that the forecasting effectiveness of the nonlinear combination model is more accurate than that of the simple average method and the linear combination mechanism, regardless of the sites and forecasting steps. The linear combination mechanism is often more effective than the simple average strategy. In other words, the simple average strategy is the worst. Therefore, the developed nonlinear combination mechanism MOEA/D-BP has successfully improved the forecasting effectiveness of power load. ### Practical Application of Load Forecasting To a Power System

Load forecasting is of great significance for how to improve the stability and reliability of power grid. Accurate forecasting results can play a decisive role in the safety and stability of power network operation. Point forecast represents the possible situation of load in a future period, while interval forecast can reflect the possible range of load. The result of load forecasting is directly reflected in the power grid planning, and the details are as follows [44]. #### 5.4.1 Application of Load Point Forecasting

Power supply load calculation needs load forecasting. According to the results of load forecasting, we can calculate the power supply load of each voltage level. The power supply load is the premise of calculating the power balance and the basis of determining the newly added variable capacitance. The network load is generally calculated according to the voltage level, which refers to the load provided by the public transformer of the same voltage level. In order to allocate the capacity of distribution network reasonably, it is necessary to predict and analyze the distribution of power supply load of each voltage level network. Point load forecasting can be applied to high voltage power grid planning. After receiving power from the upper level grid or power supply, the high-voltage grid can directly supply power to the high-voltage users, or provide power to the lower level medium voltage grid, which is the link between the transmission network and the medium voltage grid. Load forecasting is directly related to substation capacity demand and distribution in high voltage power grid planning. substation capacity demand is to determine the number and capacity of main transformer according to the prediction results of network load and the value of capacity load ratio. The distribution of substation is determined according to the load density of spatial load forecasting. Point load forecasting can also be applied to medium voltage power grid planning. In the medium voltage network planning, the load forecasting results are directly related to the distribution and transformation planning and line scale planning. The planning of medium voltage distribution is mainly to determine the capacity and distribution points of the new distribution transformer. The medium voltage line planning is mainly based on the load forecasting results to determine the number of lines to meet the growing demand for power supply [45]. #### 5.4.2 Application of Load Interval Forecasting

Analyzing the existing load forecasting methods, it is found that a large number of methods are deterministic load point forecasting results. In fact, because there are various uncertain factorsin the power system, the decision making must face a certain degree of risk, so the uncertainty of power demand must be considered in the decision-making. The results of traditional deterministic forecasting methods can not reflect the uncertainty of demand, and interval forecasting can meet this objective requirement. Interval forecasting transmits more information than point forecasting. The result of interval forecasting is a series of interval value, and this interval corresponds to a certain level of probability confidence level, which can describe the possible range of future forecasting results.