### Links

- LIOV-EMTP-rv
- Electrical Power Systems Laboratory - University of Bologna
- EMC Laboratory - EPFL
- IEEE Power Engineering Society
- IEEE Xplore
- Elsevier Sciencedirect
- International Conference on Lightning Protection - ICLP
- International Conference on Power Systems Transients - IPST
- EMTP-RV

### Recent Papers

- Napolitano, F.; Tossani, F.; Nucci, C.A.; Rachidi, F., "On the Transmission-Line Approach for the Evaluation of LEMP Coupling to Multiconductor Lines," Power Delivery, IEEE Transactions on (2014)
- F. Napolitano, A. Borghetti, C.A. Nucci, M.L.B. Martinez, G.P. Lopes, G.J.G. Dos Santos, Protection against lightning overvoltages in resonant grounded power distribution networks, Electric Power Systems Research, (2014)
- Other Papers...

# TUTORIAL

### Download PDF

Fig.1 - Geometry of the system

** **

**Code description:**

The LIOV code consists of two sub-codes: MTLF (Modified-Transmission Line Fields) and MTLV (Modified-Transmission Line Voltages).

MTLF.EXE: computation of electromagnetic field radiated by a lightning return stroke starting from the lightning channel-base current and the return stroke velocity.

MTLV.EXE: computation of overvoltage induced along an overhead line starting from the electromagnetic field calculated at a number of points along the line by MTLF.

**Input data of the MTLF sub-code:**

- Relevant to
__channel base current__.

The channel base current is expressed as the sum of two Heidler functions:

where:

and a double-exponential function:

The total channel base current is expressed as:

- Relevant to
__TL (Transmission Line model) and MTL (Modified Transmission Line model) model.__

In the TL model the channel-base current pulse propagates without attenuation:

Instead, in the MTL model the current impulse move from the base channel to up with attenuation:

- Relevant to the
__line geometry, line terminations__as well as to the__stroke location__, see Fig.1.

- Concerning the
__simulation settings__:

[0…TMIN]: temporal window in which the code MTLF calculates the electromagnetic fields at all the time step.

In the interval [TMIN…TMAX]: maximum simulation temporal window.

In (TMAX-TMIN) the code calculates the electromagnetic fields only every DTS time steps.

DELTAY : finite difference (point centered) spatial step for the evaluation of the horizontal electromagnetic field along the line.

DELTAT : finite difference (point centered) temporal step for the evaluation of the horizontal and vertical electromagnetic fields.

Maxwell’s equation for the evaluation of the return-stroke electromagnetic field are integrated along the vertical z coordinate and along the time using two integration routines (Gauss and Simpson methods).

**Example of input file for the sub-code MTLF (MTLF input file):**

5 parameter related to Simpson numerical integration steps (typical value in the range 5-15)

8.D3 H: height of the lightning channel [m]

1.3D8 v: return-stroke velocity [m/s]

10.7D3,0.25D-6,2.5D-6,2.D0 I01[A],TAU11[s],TAU12[s],N1 parameters of the 1st Heidler current

6.5D3,2.1D-6,230.D-6,2.D0 I02[A],TAU21[s],TAU22[s],N2 parameters of the 2nd Heidler current

0.D0,0.5D4,3.D5 ID[A],ALFA[s-1],BETA[s-1] parameter of the double exp current

1.D-6 parameter related to Gauss integration routine precision

(typical value in the range 1.D-3 – 1.D-6)

3 Option for Classical TL model (set =1) or MTL (set =3)

2.D3 LAMDA current decay parameter

1.D3,7.5D0 OL: line length, h: line height [m]

50.D0,-500.D0 D1,D2 stroke location coordinates [m]

(this corresponds to a stroke location at 50 m from the line centre and equidistant to line terminations)

2.D-6 TMIN: 1st temporal window [s]

7.D-6 TMAX: maximum temporal window [s]

10. DELTAY: spatial step [m]

3.D-8 DELTAT: time step [s]

20 DTS: time interpolation steps in the interval [TMIN-TMAX]

**Input data of the MTLV sub-code:**

The inputs of MTLV sub-code are:

- FIELD file generated by MTLF sub.code
- LINE input file.

In the second input file the user can specify the following values:

Conductor diameter

Value of the termination resistances.

**Example of input file (LINE input file) for the sub-code MTLV:
**

1.D-2 Conductor diameter [m]

500.D0,500.D0 R0 [Ohm]: line terminal resistance at D2=0 ,RL [Ohm]: line terminal resistance at D2=line lenght

**Computation procedure:**

1 – Start calculating the field running the MTLF.EXE sub-code. Use only one input file (MTLF input file). The code will ask you the number and location of the observation points along the line (maximum number is five). This code will generate the “FIELD” file, the name of which is defined by the user upon request of the code. This “FIELD” file is one of the two input files of the MTLV.EXE sub-code.

2 – Start calculating the over-voltage running the MTLV.EXE sub-code. Use as inputs the “FIELD” file and the LINE input file. This sub-code generate a group of *.dat file that contains the overvoltage results. The number of these *.dat files is equal to the number of observation points chosen by the user plus two (corresponding to the two voltages at the line terminations)

The *.dat files can be plotted using for instance Microsoft Excel ™ in a straightforward manner.

Below find the output relevant to the input files of this “read me file” (voltage at the line terminations).

### Multimedia section... coming soon

### Visit the tutorial subsection to learn more about the LIOV code

**Direct link to examples**:

coming soon..

- line 1
- line 2