Electric Power Transmission

1.    Transformer. Switching, phase shift. Winding power, throughput power. Types of transformers in Hungary. Autotransformers. HV/HV autotransformers, on-load tap changing. Parameters, calculation of symmetrical conditions. 22/0.42 kV transformer in the network. Parameters, , calculation of symmetrical conditions.

2.    Impedances and capacitances of overhead lines. 4-wire model. Self and mutual impedances and capacitances. Symmetrical impedances and capacitances. Line asymmetries, symmetrisation. Calculation of series impedances and capacitances of overhead lines. Tower constructions of overhead lines. Calculation of inductances of overhead lines. Role of the protective wire. Double circuits, coupling in zero order.

3.    Cables. Structure, electric parameters. Warming of cables. Operation of HV transmission lines. Distributed model, line parameters. Charging power, surge impedance power. Characteristic electric parameters. Concentrated T and Pi model, U-I phasor diagrams, approximate calculation of Q-flows. Evaluation of HV line operations: (1) open circuit, voltage profile, (2) active power flows, phase angle difference. Power losses of transmission networks: interpretation and components.

4.    Limits of power transmission. Current loading, voltage stability, synchronous stability. Increasing transmission capabilities, FACTS devices. Cross-border capacities: interpretation and definitions. HVDC transmission. HVDC converter stations. Power transmission in HV AC and DC systems. Structure and application of HVDC. Advantages and disadvantages of HVDC. Operation and control of HVDC converter stations.

5.    Control with HV transformers. Switching of shunt reactors. Effects of lengthwise and widthwise control of HV transformers in looped networks. Phase shift transformer.

6.    MV and LV networks, voltage control, power losses. Roles in distribution network. Typical transformers, line cross sections, electric parameters. Structure of MV and LV networks, voltage profiles, regulations, voltage drops. Voltage control. MV and LV power losses.

7.    Calculation of looped HV networks. Calculation models, basic relationships. Interpretation and application of I=Y*U and U=Z*I nodal equations. Determination and measurement of Y and Z. Equivalent models based on Z. Network reduction.

8.    Load-flow calculations on looped HV networks. Nonlinear nature of the task, theorem of iteration solutions. Data, parameters, nodal models. Basic equations, solutions. Representation of the results.

9.    Representation and calculation of short-circuits and switches with symmetrical components. Comparison of short-circuits. Principles of short-circuit current limitation. Calculation of simultaneous faults. Asymmetrical loading of 0.4 kV networks. Solutions using phase quantities and symmetrical components. Interpretation, analysis. Terminal short-circuit of transformers. Currents, effect of Yd and Dy windings. Earthing transformer, structure, role. Currents and voltages of short-circuits on power lines. Currents and voltages using 4-wire model. Phasor diagrams, symmetrical components.

10.  Earthing methods. Effect of star point earthing in case of single-phase-to-ground faults, current-voltage phasor diagrams.

11.  Voltage sag, loss of phases on 120/MV/0.4 kV radial networks. Phase-to-ground faults, voltage distortion effect of single-phase switch openings, spread of the effects, role of Yd and Dy transformers. Operation under faulty conditions. Three-phase short-circuit current, short-circuit power, voltage sag.

12.  Busbar and substation topologies, principles. Busbars, feeders, devices, current and voltage transformers. Double busbar system, breaker-and-half system, other topologies.

13.  Protection devices in the power system. Basic definitions. Role and requirements of protection. Structure and role of protection. Detection methods. Protection of MV busbar and feeders. Protection of radial networks. Coordination of current thresholds. Delayed overcurrent protection. Breaker failure protection. Busbar protection. Distance-time characteristic of protection schemes.

14.  Network development. Design standards (ENTSO-E, Operating Rules, Distribution grid codes), methods, calculations. The European power system. Basic characteristics. Maps, differences between the European and the Hungarian network. Grid connection. Prerequisites, contracts, fees. Power supply of electric traction. Circuits, voltage levels feeding stations used in traction.