AC Transmission Line Protection Based on Current Energy Ratio for
Renewable Energy Delivery System
AbstractThe power-electronics-based renewable power plants are currently
experiencing rapid growth in various power systems. Their variable
control strategies have altered the power transmission line fault
characteristics, which leads to problems for the protections that rely
on a linear estimation of the power frequency fault information, even to
the point of the refused operation risk of protection. Therefore, this
paper proposes a new protection algorithm based on a current energy
ratio for the transmission line connecting to renewable power plants.
The current fault characteristics are investigated in detail, and their
energy relationship is adopted to fully distinguish internal and
external faults. When an internal fault occurs, there are large
differences in energy ratio of transient current on both sides. Energy
ratio can be used to measure the degree of variation to distinguish the
faults inside and outside the line. Simulation results show that faults
of different fault resistances can be distinguished within 10 ms.
Moreover, the proposed method requires a conventional sampling frequency
and a computation speed that can be met by most protection devices.
Thus, the proposed algorithm provides a better solution to the
transmission line protection problem. These features make the proposed
method a good choice for industrial application.