Моделирование высокочастотной дифференциально-фазной защиты линий электропередачи 220 кВ
Аннотация
Nowadays two main types of protection schemes widely used in protection of transmission lines are: distance protection and differential protection schemes. However, it has been noticed from industrial practice that the distance protection scheme used today generally is limited in tripping speed and selectivity. Also differential protection scheme is influenced by the time synchronization of samples in both relays installed at transmission line terminals. On the other hand, among various pilot protection schemes or protection of Extra High Voltage (EHV) / Ultra High Voltage (UHV) transmission lines, the schemes which use communication link only for exchange of local decision making about faults’ status are not affected by time synchronization.
This bachelor thesis is dealing with the issue of developing reliable and fast fault detection scheme for protection of EHV/UHV transmission lines which is a requirement in modern power systems. The protection algorithm proposed in this thesis is based on the detection and analysis of High Frequencies on transmission lines at inception of the faults. This algorithm relies on the action of differential-phase high-frequency (HF) protection (DHFP) which is based on the principle of comparing the phases of currents at the ends of the protected power line. Operation at all types of short circuits (short circuits) is provided by phase comparison of the sum of the currents of positive and negative sequences formed by the corresponding measuring converters of asymmetric three-phase currents into single-phase, proportional to symmetrical components and their combinations — filters and symmetrical components of currents
Finally, by simulations carried out in MATLAB-Simulink environment practical design considerations for implementing the new developed protection algorithm in a numerical relay unit is investigated. The results of simulation show that the proposed pilot protection scheme solves several issues encountered by using the conventional schemes and provide reliable and high-speed protection for transmission lines.
Keywords: Transmission line protection, UHS relaying, Differential Phase High Frequency Protection Relay.
This bachelor thesis is dealing with the issue of developing reliable and fast fault detection scheme for protection of EHV/UHV transmission lines which is a requirement in modern power systems. The protection algorithm proposed in this thesis is based on the detection and analysis of High Frequencies on transmission lines at inception of the faults. This algorithm relies on the action of differential-phase high-frequency (HF) protection (DHFP) which is based on the principle of comparing the phases of currents at the ends of the protected power line. Operation at all types of short circuits (short circuits) is provided by phase comparison of the sum of the currents of positive and negative sequences formed by the corresponding measuring converters of asymmetric three-phase currents into single-phase, proportional to symmetrical components and their combinations — filters and symmetrical components of currents
Finally, by simulations carried out in MATLAB-Simulink environment practical design considerations for implementing the new developed protection algorithm in a numerical relay unit is investigated. The results of simulation show that the proposed pilot protection scheme solves several issues encountered by using the conventional schemes and provide reliable and high-speed protection for transmission lines.
Keywords: Transmission line protection, UHS relaying, Differential Phase High Frequency Protection Relay.