Research on Monthly Security Checking Method of Power Grid Large Consumer Direct Electric Quantity Purchasing

To realize the grid security checking of large consumer direct electric quantity purchasing plan, a monthly security checking method of large consumer direct electric quantity purchasing based on grid partitions is presented in the paper. In the method, a power grid is divided into security partitions containing a certain number of units and loads, and the monthly electric quantity decomposition and the daily electric quantity decomposition models with the constraints of electric quantity and power in the partition being considered are built. That the power flow of the tie line is less than the allowed stability limit value is one of the constraints in the electric quantity trading of different partitions. The partition electric quantity deviation is reflected in the form of slack variables in the constraint conditions, and the minimum slack variable is used as the optimization target to optimize the built models. To realize the monthly security checking of the contract electric quantity, the monthly contract electric quantity is decomposed to days considering electric quantity constraints, and the daily electric quantity is decomposed to hours combining the output levels of units. Finally, an example of the IEEE 39 node test case is constructed, and the effectiveness and feasibility of the presented security checking method is verified by setting different direct power purchasing electric quantity of units.