Model of Airport Ground Lighting System Transformers

Airport ground lighting (AGL) systems provide visual reference to aircrafts during airport operations. In AGL systems, constant current regulators feed a beacon circuit supplied through isolation transformers. Component modeling is necessary to simulate AGL systems, and thus characterize and predict their behavior. This paper presents an isolation transformer model including transformer core saturation. Moreover, a procedure to estimate transformer model parameters is proposed. Both the model and the estimation method are validated with extensive measurements on more than 20 isolation transformers of different power ratings and trade names. Nomenclature f Frequency of the supply voltage T Period of the supply voltage  Angular pulsation of the supply voltage R Winding resistance of the transformer Rp, Rs Primary and secondary winding resistances X Leakage reactance of the transformer Ld Leakage inductance of the transformer Ldp, Lds Primary and secondary leakage inductances RFe Core loss resistance M Core non-linear magnetizing inductance up, us Primary and secondary transformer voltages ip, is Primary and secondary transformer currents im Magnetizing current iFe Core loss resistance current  Core magnetic flux p Core magnetic flux across the primary winding ftc Magnetic potential in the transformer core (ftc) Non-linear reluctance Np, Ns Primary and secondary winding turns rt Winding turn ratio up, sc Primary voltage measurements of the short-circuit test ip, sc Primary current measurements of the short-circuit test up, 0, ip, 0 Primary voltage and current measurements of the open-circuit test us, 0 Secondary voltage measurements of the open-circuit test pFe Transformer active power consumption PN Rated power of the isolation transformer D Length of the underground cables PB Active power of beacons RB Resistance of beacons y Vector of the magnetizing inductance function parameters r(y) Residual vector ylb, yub Lower and upper bound vectors of the magnetizing inductance function parameters M1, M2, p and i0 Parameters of the magnetizing inductance function