Calculation of load supply capability for distribution networks with distributed generations

Based on the studies of load supply capability (LSC) for the traditional distribution network, this paper has established computational model of LSC of the network with distributed generations (DGs). DGs can be processed as PQ node, PV node, PI node or PQ(V) node according to their access mode and control strategy in power flow calculation. For the changes of network configuration and power distribution, back/forward sweep method in the form of branch current is selected to calculate power flow, which possesses rather strong processing ability for different node types of DGs and looped networks. And the incident matrix of node voltages and injection currents is deduced to accelerate iteration speed. On this basis, variable step-size repeated power flow algorithm is adopted to calculate LSC. Meanwhile, the corresponding weak link of the network is judged. IEEE33-node distribution network is taken as an example and programmable computed in Matlab2010a, which verifies the effectiveness of proposed model and algorithm.