Security region based security-constrained economic dispatching method

A security region based security-constrained economic dispatching method, which comprises the following steps:

• Step 1:
• presetting parameter, network system topology parameter, cut-sets for the static voltage stability, contingency sets for the transient stability and power flow limit value for branches, calculating the coefficients for the active power static security region, the cut-set voltage stability region and the dynamic security region;
• Step 2:
• building the models for security region based security-constrained economic dispatch, which can be divided into the following models according to the optimization goals:
• (1) model I, which takes the minimum total generation cost as its optimization goal, and the constraint conditions comprises the operating constraints of units, system power balance and spinning reserve constraints;
• (2) model II, which takes the minimum total generation cost as its optimization goal, and the constraint conditions comprises the operating constraints of units, system power balance and spinning reserve constraints, and network security constraints;
• (3) model III, which takes the maximum static voltage stability margin as its optimization goal, and the constraint conditions of which are same as that of model II;
• (4) model IV, taking the maximum transient stability margin as its optimization goal, and the constraint conditions of which are same as that of model II;
• (5) model V, which transforms the minimum total generation cost, the maximum static voltage stability margin and the maximum transient stability margin into a single optimization goal via the weighting method, and the constraint conditions of which are same as that of model II;
• The model is divided into on/off state optimal sub-problem and load economic dispatching sub-problem to be solved;
• Step 3:
• solving the unit on/off state optimal sub-problem through social evolutionary Programming, obtaining the optimal on/off states of unit for the dispatching period, calculating the start-up cost of units for the dispatch period, and achieving the actual upper and lower limit values for active power output for units with considering the ramp rate constraints of units;
• Step 4:
• taking the on/off states and limit values for active power output of units as the input values, and solving the load economic dispatch sub-problem according to the optimization goal, i.e., optimal dispatching the active power output of units and calculating the generation cost, static voltage stability margin and the transient stability margin of units;
• Step 5:
• obtaining a feasible economic dispatching scheme through step 3 and step 4, and determining whether it satisfies the convergence condition:
• if yes, then stop;
• otherwise, return to step 3.