New iterative method for Available Transfer Capability calculation

This paper presents a new iterative method to calculate Available Transfer Capability (ATC) of the interconnected transmission network that can be used in realtime. In today´s deregulated power system, large scale power transactions between utilities have increased to supply reliable and economical electric supply. In this situation, fast and accurate determination of ATC in real-time is very important. Existing linear ATC calculation methods are either based on DC or AC Power Transfer Distribution Factors (PTDF). These methods are fast but do not consider control changes such as generator reactive limits and voltage limits as the transfer limit increases. Continuation Power Flow (CPF) can produce accurate ATC values, but it requires repeated solution of power flow and hence can be very time consuming. Optimal Power Flow (OPF) based methods can also determine accurate ATC values, but solution of optimization problem makes it very slow. The proposed iterative method overcomes disadvantages of existing methods. The proposed can also be described as linear predictor only continuation method but it does not require repeated solution of power flow which makes it faster. It also considers the control changes of the system with the increase in transfer limit. The simulation results are presented on IEEE 6-bus and 39-bus systems. The results are compared with the results obtained using DC-PTDFs, AC-PTDFs and repeated AC Power Flow (ACLF).