Evaluation of Voltage Phase Fluctuations in Power Networks with Rapid Variable Loads

This paper presents a method for calculation of the voltage phase fluctuations in power networks due to the operation of the electrical energy consumers with rapid variable nature of the active and reactive power consumption. The operation of these power consumers leads to the simultaneous occurrence of the voltage frequency and voltage phase fluctuations in the power system load nodes. The voltage frequency fluctuations appear because of mechanical transients in power station "generator – turbine” blocks of energy system. Voltage phase fluctuations are associated with variations of the value of the transverse component of the voltage drop on the equivalent power system impedance, in relation to a concrete power system node. Considering the processes of power consumption value variations caused by above mentioned consumers as random processes with known parameters and types of correlation functions of consumers’ load diagrams, are obtained expressions which give the possibility to assess the variances of the corresponding voltage phase fluctuation graphs in the analysed power system node. The carried out calculations allow defining the conditions that depend on the permissible calculation accuracy, when it can neglect the influence of the voltage frequency variations in the power system under assessing the voltage phase fluctuation values in the power system node, where rapid variable consumers are connected. The analysis of the calculation results allows also revealing the basic parameters of the power spectrum of rapid variable power consumption graphs of users. These parameters have a practical influence on the values of the error assessments for voltage phase value fluctuations at power system nodes. Keywords—Voltage phases variations, voltage frequency variations, power systems, rapid variable loads.