Bus Admittance Matrix Estimation Using Phasor Measurements

The Bus Admittance Matrix, Y-bus, of a power system is used to perform various calculations in power system operations. The calculations include load flow analysis and state estimation of power system. Currently, the Ybus is calculated using the offline models of power system elements derived during their design. The off-line models can be erroneous because of the mistakes in calculations due to human error. If such an error occurs, it will be hard to detect. Additionally, the parameters of power system elements can vary depending on the system and atmospheric conditions. These variations are not reflected in the off-line models which are seldom updated to accommodate parameter variations. Using erroneous or not updated offline models of the components may result in an inaccurate Y-bus of a power system. To avoid these shortcomings of the current offline approach, a measurement-based approach is proposed for the estimation of the bus admittance matrix. Such an approach is preferable since it is adaptive to network changes and is less prone to error. In the proposed method, least-squares estimation is applied on the phasor measurements to approximate the bus admittance matrix of a power system. This technique is applied to an IEEE-14 bus system and the convergence of the algorithm is discussed.