REI method for multi-area modeling of power systems

• Interconnection of electricity markets has increased the size of recent power systems.
• High penetration of wind power has also augmented the uncertainty of these systems.
• Multi-area based modeling of bulk power systems with high wind is given in this paper.
• Admittance matrix and REI method are used in obtaining the multi-area equivalent.
• The method is based on AC power flow rather than the DC one.

Interconnections between different electricity markets and high penetration levels of wind power have resulted in an increase in the size of power systems with higher levels of uncertainties. This paper presents an algorithm for bulk power system simulations with large wind power penetrations, based on multi-area modeling with transmission constraints. The present study differs from previous multi-area studies by taking into account the capacity of intra-area lines during the simulations, which leads to more accurate results. The method that we introduce consists of three steps. First, a power system with high wind power penetration is divided into several areas using a practical measure, admittance matrix. Second, the internal system of each area is replaced with a smaller system, to which an improved version of the REI (Radial, Equivalent, and Independent) method is developed and applied. Finally, the technical properties of the reduced power system (such as voltage limits and transmission capacities) are tuned by adjusting optimization, in a way that the simulation results of the reduced power system are comparable with those of the original system. The IEEE 30-bus and IEEE 118-bus test systems are used to show the efficiency of the proposed algorithm.