The Study On Load Curtailment Optimization In Urban Electric Network

The purpose of the power system risk assessment is to evaluate the risk of load loss led by all operation states--the load level of all nodes in high states including summer peak, and the change of network structure when some units run out due to system maintenance or fault. In the process of power system risk assessment, modeling and algorithms for unit outage, load profile, state choice, and indices calculation will be needed, for one important thing, it is needed to evaluate whether the network needs load cutting and the quantity of load curtailmentfor given operation states.The load curtailment optimization is defined as when system in state of N - k , to avoid load curtailments if possible, or minimize the total load curtailments if unavoidable by rescheduling generation outputs and load transfer. The model is not only the crucial part in the power system risk, but the supplement and improvement of the static security evaluation. The calculation speed of the model is the basic requirement, since the states of the network are numerous by state enumerating or Monte Carlo simulation.Based on the power system risk analysis and matching the requirements of urban network risk analysis, the two mathematic models of linear programming algorithm for load curtailment optimization is founded. The object function is considered the difference of weight values of load node for the different load character, the equation constraints are power balance including balance in all the network, node power, and branch power, and the inequation constraints are branch power limit, generation output limit, and the load curtailment limit.To verify the effectiveness of the model and calculation proposed, the computer programs are designed to analyze the load curtailment quantity of 5-bus system in three states. The model is also applied to calculate the risk indices in Foshan urban network with hundreds nodes which help to solve problems for the network risk evaluation in a practical engineering project.The application in the practical engineering field is prospected at the end of the paper.