How are the zero sequence and negative sequence networks connected in case of LLG faults?

In case of LLG faults, Zero sequence & negative sequence networks are connected parallel. Q.

What is single phase to ground fault?

Generally, a single line-to-ground fault on a transmission line occurs when one conductor drops to the ground or comes in contact with the neutral conductor. Such types of failures may occur in power system due to many reasons like high-speed wind, falling off a tree, lightning, etc.

Which of the following impedances are considered for a single line to ground fault?

From the above expression of fault current, it is quite clear that positive, negative and zero sequence impedance are connected in series for Single Line to Ground Fault and the equivalent circuit may be represented as shown below.

How do you calculate phase to ground?

In a standard phase-to-phase connection, the variable that represents the grounding force is 1.73; it is divided from the voltage in order to compensate for the ground in a circuit. Using the same sample equation 12*5=60 volts, we can account for the ground by dividing 60 by 1.73, making the new voltage 34.68 volts.

How do you calculate fault current?

Fault current calculations are based on Ohm’s Law in which the current (I) equals the voltage (V) divided by the resistance (R). The formula is I = V/R.

What is sequence network?

Definition: The sequence impedance network is defined as a balance equivalent network for the balance power system under an imagined working condition so that only single sequence component of voltage and current is present in the system.

In which fault all sequence network are connected in series?

LG faults
Hence in LG faults, all of the three components la0, la1, and la2 are equal. From the above equation, it is clear that to simulate an L-G fault all the three sequence networks are required and since the currents are equal in magnitude and phase angle, the three sequence networks must be connected in series.

What is Llg fault?

Double Line to Ground Fault (LLG): Figure 11.9 shows a Double Line to Ground Fault at F in a power system. The fault may in general have an impedance Zf as shown. The current and voltage (to ground) conditions at the fault are expressed as. The symmetrical components of voltages are given by. from which it follows that.

What is double line to ground fault?

In double line-to-ground fault, the two lines contact with each other along with the ground. The probability of such types of faults is nearly 10 \%. The symmetrical and unsymmetrical fault mainly occurs in the terminal of the generator, and the open circuit and short circuit fault occur on the distribution system.

What is the faulted phase of a single line?

Thus for faulted phase, in case of Single Line to Ground Fault, we can write First thing which must be understood at this point, that fault current is completing its path through the grounded neutral. If there were no any grounded neutral, no fault current would have been flow.

Does current flow from a single line to a ground fault?

By principle, the single line to ground fault will develop and equivalent network where all sequence networks are connected in series. The zero values of phases B and C confirmed that no fault current flows from it during fault condition.

Where does the phase-ground fault start and end?

Phase-Ground fault starts at dotted red cursor and ends at magenta cursor. Phase-Phase fault starts at magenta cursor. Top graph shows line voltage. Middle graph shows phase current and bottom graph shows ground current. Negative sequence current exists during a phase-ground fault and during phase-phase fault.

How do you calculate IF-1 and IF-2 for ground faults?

By principle, the single line to ground fault will develop and equivalent network where all sequence networks are connected in series. then, If-1 = 1 (angle 0)/ (Z0 + Z1 + Z2) = -j 2.22 pu or 2.22 (angle -90) also it means that, If-2 = If-0 = – j 2.22 pu Multiplying the base value