A feeder protection method against the phase-phase fault using symmetrical components

Negative Sequence-Based Schemes for Power System Protection - Review and Challenges

“…Reference [19] suggested to measure the ratio of the negative sequence current to the positive component to identify faults in radial feeders; the study showed that the ratio value would increase when the fault is closer to the measuring device.…”

Improved protection system for phase faults on marine vessels based on ratio between negative sequence and positive sequence of the fault current

“…In other words, in a radial feeder, the nearest upstream CT to a PP fault will depict the highest magnitude of the ratio between the current NSQ and current PSQ. Precisely, this information is used in [12] to achieve coordination of those protection relays that rely on the ratio between the current NSQ and current PSQ. However, such coordination is not possible without communication between the protection relays and consequently, a new method of relay coordination that does not require communication is proposed in the following section.…”

“…Overcurrent (OC) protection is widely used for detection of these abnormal conditions on vessels [1], but its correct operation can be compromised in some cases. For example, variable generation may lead to variation of the available short-circuit power, thereby endangering coordination of the OC relays [4], while the relatively reduced fault currents could cause longer tripping times for the relays [12]. Moreover, these protection problems could be more pronounced in the future, as it is anticipated that the new vessel designs will introduce more variable generation and load levels [13].…”

“…In response to the protection issues caused by variable short‐circuit power in maritime applications, a new method of protection has been suggested in [12] against PP faults. The method proposed in [12] uses symmetrical components of the fault currents and communication between the protection relays to clear PP faults in a maritime feeder in a selective manner. However, if communication between the protection relays is lost then coordination is no longer possible and the protection system loses selectivity.…”

“…Also, the relay‐dedicated communication is not always available on vessels and when it is available, a back‐up protection method is still needed in the event of a communication failure scenario. In this paper, the protection method proposed in [12] is modified so that communication is no longer required, thus making it suitable for a wider range of vessels. The newly developed method of protection addresses PP faults because 3P faults are very rare on vessels and usually develop from PP faults [13], while PG faults do not produce significant fault currents on vessels, as discussed previously.…”