Voltage conditions estimation in frequency domain of power systems based on measuring power quality

Abstract

Power quality (PQ) is becoming important factor in proper functioning and operating of power systems (PS). Continuous PQ monitoring represents basics for efficient exploitation of power systems. Systems for continuous PQ monitoring and their networking with central system are major investments. This paper lists conditions for modeling of certain PS elements and describes concept of power network modeling in PQ analysis. First part of the paper gives mathematical formulation of the problem; second part describes high voltage transmission line in frequent domain using system of phase values, while the third part of the paper is an example in time domain modeled in EMTP-RV software package using system of phase values. Performance of power network in quasi-stationary state is analyzed and during the simulation five changes of voltage conditions occur as consequence of overloading. The PS is loaded with nonlinear loads generating high current and voltage harmonics. Voltage and current harmonic in the places of energy exchange are observed; furthermore estimation of voltage harmonics in the places with no PQ monitors is conducted. Conclusions of the paper indicate possible usage of presented algorithm for real time PQ analysis and for post PQ analysis.