| 摘要 |
A method for determining temperatures (tqm, tqh, tom, tok) in an oil cooled transformer, whereby transformer terminal voltages, currents per winding (3) and ambient temperature (6) are measured. The status (5) of ventilators and pumps and the position (4) of a step switch are also determined. The variables (2, 3, 4, 5, 6) that are measured and determined are fed to a thermohydraulic model (7), whereby state variables (19) are calculated using auxiliary variables (9) i.e. transformer loss (10), heat transfer convection parameters (11), flow resistance (13) and oil flow (12). The state variables (19) are average temperatures (tqm) and hot spot temperatures (tqh) in transformer parts that produce losses and the average oil temperatures in branches (tom) and nodes (tok) of the hydraulic network of the oil circuit. Whenever the measured and determined variables (2, 3, 4, 5, 6) are modified, the auxiliary variables (9) are adjusted accordingly, the speed at which the state variables (19) are modified is determined and new state variables (19) are calculated. The inventive method enables temperatures (tqm, tqh, tom, tok) and modifications in the temperature to be determined without a temperature sensor. Optimum operation of the transformer is thus guaranteed, errors and risks are recognized at an early stage and the optimum moment to carry out service work can be specified.
|
