Toshiba GR200 Series Instruction Manual page 118

Line differential protection ied

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That is, the positive-sequence impedance Z

the simple ratio of voltage V a to compensated current I a ' according to equation (2.10-14).

Obtaining the compensated current according to equation (2.10-13) is called "zero-

sequence compensation." Note that in this implementation of zero-sequence compensation, the

compensation coefficient

are not real numbers, but complex numbers. The distance protection function has a

configuration that allows this compensation coefficient to be set as a complex number and

setting the coefficient correctly makes it possible to measure exactly the distance to the fault

In equations (2.10-7) to (2.10-9), the fault resistance is ignored. Since the measurement

of the distance up to the fault point, based on equation (2.10-14) is carried out using the

reactance component, in principle there is no influence on the voltage component due to the

fault resistance. However, under real operating conditions, distance measurement errors are

introduced because of the fault resistance combined with the power flow or the current flowing

into the fault point from the remote terminal opposite to the relay location.

Positive-sequence circuit

Negative-sequence circuit

Zero-sequence circuit

Figure 2.10-3 Equivalent circuit of single-phase earth fault

up to the fault point can be obtained from

6F2S1914 (0.49)

GRL200 (Soft 033 & 037)

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