Transient Effects in Electrical Systems

Lectures:

- Definition and classification of transients.
- Electromagnetic transients in power systems.
- Three-phase short circuit fed by an ideal source.
- Three-phase short circuit of a synchronous machine.
- Three-phase short circuit at the terminals (near) an asynchronous motor.
- Characteristic values ​​of short circuit current in a general network.
- Parameters of power system elements in symmetrical component systems.
- Unsymmetrical operating states of a power system.
- Notes on practical calculation of short circuit currents.
- Calculation of short circuit currents in complex power systems.
- Dimensioning of electrical equipment according to the effects of short circuit currents.
- Earth faults in power systems (in isolated and compensated medium-voltage power grids).
- Transient overvoltages at (intermittent) earth faults.
- Electromechanical transients in power systems.
- The essence of electromechanical transients.
- Static stability (stability of small oscillations) of a simple system alternator - power grid with constant voltage and frequency.
- Dynamic stability (transient stability) of a simple system - rule of areas, oscillation curve.
- Stability of a complex power system.
- Asynchronous operation of a power system.
- Means for improving the stability of a power system

Exercises:

- Introduction, safety training, conditions for obtaining credit.
- Analysis of circuits using the symmetrical components method.
- Short circuits: Calculations of short circuit currents according to ČSN EN 60909-0 (Short circuit currents in 3-phase AC systems).
- Short circuits: Calculations of symmetrical short circuits and asymmetrical short circuits.
- Short circuits: Influence of asynchronous motors on short circuit ratios.
- Short circuits: Checking equipment for the effects of short circuit currents.
- Short circuits: Dimensioning of equipment for thermal and dynamic effects of short circuit currents.
- Earth faults in MV power grids: Calculation of ratios during earth faults.
- Earth faults in MV power grids: Setting/tuning of the compensating coil (quenching choke).
- Power system stability: Calculation of static stability (stability of small oscillations).
- Power system stability: Calculation of dynamic stability (transient stability).
- Assignment and development of an independent semester project.
- Credit test.

Laboratory measurements:

- Measurement of short-circuit currents using physical model.
- Measurement of Earth fault using physical model.

Projects:

- Modeling and calculation of short circuit ratios (a/symmetrical short circuit currents) in the electrical distribution network, including using selected software.