Algorithms of Estimation of Turbogenerator Synchronous Reactance and Criteria of Selecting Proper Synchrophasor Measurement Data Sets

To increase the reliability and efficiency of the operation of electrical-power systems, it is important to use the current values of the parameters of the models of their elements, in particular, synchronous generators (SGs). Synchronized phasor measurement technology potentially provides the opportunity to identify the actual parameters of synchronous-generator models using steady-state and transient measurements of electrical-power systems without disconnecting the generators from the network and conducting specialized tests. When solving the problems, the principles of the theories of electrical circuits, electrical machines, optimization and statistics, and the apparatus of matrix algebra were used. The developed identification method is implemented in the MATLAB software package. Testing of the presented identification method was carried out on the basis of real data obtained from a synchronized phasor measurement device installed on a turbogenerator of a large power plant of the Unified Energy System of Russia. A method for determining the synchronous reactance of a turbogenerator using data from synchronized phasor measurements measured in a series of steady-state electrical power modes is presented, and criteria for selecting the composition of the data necessary for successful identification are considered. The corresponding algorithm was developed and implemented in the MATLAB software package. To improve the accuracy of solving the identification problem, a method is proposed for adjusting the nominal value of the generator no-load excitation current depending on the heating of the excitation winding. The method was successfully tested on the basis of a data set of steady-state modes of one of the turbogenerators of the Unified Energy System of Russia. Quantitative criteria were developed and analyzed to determine a set of measured parameters of steady-state conditions, providing the most accurate identification of the value of the synchronous reactance of the turbogenerator model. The developed method makes it possible to successfully update the synchronous parameters of a turbogenerator using synchronized phasor measurements recorded in a series of steady-state modes of electrical-power systems. Using criteria for selecting the composition of synchronized phasor measurement data, it seems possible to automate the process of generating an array of measurement data of various steady-state modes necessary for subsequent identification. The proposed calculation expressions for taking into account the temperature of the excitation winding can be used in mathematical models to identify transient and subtransient parameters of synchronous-generator models based on data from synchronized phasor measurements in transient modes of electrical-power systems.