A method for real power transfer allocation using multivariable regression analysis Hussain Shareef 1 , Azah Mohamed 1 , Saifunizam Abd. Khalid 2 , Mohd Wazir Mustafa 2 1. Faculty of Electrical Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia; 2. Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Johor, Malaysia Abstract: A multivariable regression (MVR) approach is proposed to identify the real power transfer between generators and loads. Based on solved load flow results, it first uses modified nodal equation method (MNE) to determine real power contribution from each generator to loads. Then, the results of MNE method and load flow information are utilized to determine suitable regression coefficients using MVR model to estimate the power transfer. The 25bus equivalent system of south Malaysia is utilized as a test system to illustrate the effectiveness of the MVR output compared to that of the MNE method. The error of the estimate of MVR method ranges from 0.001 4 to 0.007 9. Furthermore, when compared to MNE method, MVR method computes generator contribution to loads within 26.40 ms whereas the MNE method takes 360 ms for the calculation of same real power transfer allocation. Therefore, MVR method is more suitable for real time power transfer allocation. Key words: power tracing; multivariable regression; power systems; deregulation 1 Introduction The introduction of electricity privatization becomes an important issue under electric industry restructuring. The aim of this research is to bring transparency and open access to the transmission network. Implementing transparent rules that allocate transmission use fulfill this concept of fairness in the industry. Fairness can only be achieved by adopting a fair and transparent usage allocation methodology acceptable to all parties. In view of market operation, it is vital to know the role of individual generators and loads to transmission wires and power transfer between individual generators to loads. This is necessary for the restructured power system to operate economically, efficiently and ensure open access to all system users [1]. Several schemes have been developed to solve the allocation problem in the last few years. Methods based on the Ybus or Zbus system matrices have recently received great attention since these methods can integrate the network characteristics and circuit theories into line usage and loss allocation. The method reported in Ref. [2] is based on Kirchhoff’s current law (KCL), equivalent linear circuit that reaches all lines and loads. Based on the stated assumptions, a recursive procedure was used to construct the equivalent circuit for each bus. Moreover, superposition theorem was applied to the bus’s equivalent circuit starting from a bus whose injected currents were known. Another circuit concept method was proposed by CHANG and LU [3]. It was based on the Ybus system matrix and Zbus modification. Starting from the load flow solution, branch currents are determined as a function of generators’ injected current by using information from the bus impedance matrix. Similarly, contribution to bus voltages was computed as a function of each generator current injection by decomposing the network into different networks. Using the computed voltages and currents, the power flowing on the transmission lines was unbundled. It uses approximate formulation to calculate the unbundled loss components. This algorithm utilizes the network decomposition concept as proposed by ZOBIAN and ILIC [4], which determines the use of transmission network by individual bilateral contracts. TENG [5] proposed a systematic method, very similar to that presented in Ref. [3], to allocate the power flow and loss for deregulated transmission systems. Using similar concept, a modified nodal equation (MNE) method is introduced for real and reactive power allocation [6], in which the load bus powers are represented as a function of the generators’ current and voltage. The tracing methods [1, 7−10] based on the actual power flows in the network and the proportional sharing principles were effectively used in transmission usage allocation. The methods reported in Refs. [1, 9] are based on tracing current and complex power from individual power sources to system loads. Based on solved load Received date: 2011−05−20; Accepted date: 2011−07−05 Corresponding author: Hussain Shareef; Tel: +603−89216590; Email: shareef@eng.ukm.my