SINT
ENGINEERING CONSULTING
AND SOFTWARE
Network Solver
NETS can be used for analysis of multi-conductor and multi-phase full meshed networks also in cases of multiple connection to earth (when the sequence components method cannot be applied) and is commonly used for the evaluation of current distribution in fault and steady state conditions in cables and power lines, including the evaluation of current along screens, armors and overhead earth wires.
NETS can be used also for the evaluation of fault current distribution and and is commonly used for the split factor calculation in general conditions.
NETS can be used also for electromagnetic interference analysis of aboveground and underground systems at power frequency, and is commonly used for the evaluation of interference between power lines or cables or railways and pipelines.
NETS is highly appreciated for its power, accuracy and flexibility.
GENERAL DESCRIPTION
NETS is a computation code for the solution of full meshed multi-conductor and multi-phase underground and/or overhead networks in the frequency domain. The application range is limited to the model accuracy of transformers (up to 1 kHz) cables (up to 1 kHz) and lines (up to 10 kHz).
NETS is based on the phase components method (and then on Kirchhoff laws) and graphs theory for multi-conductor and multi-phase systems. The phase components method is general and overcomes the limits of the classic sequence components method and can be used to represent power systems as multi-conductor networks enabling the consideration of non-symmetrical systems also in presence of multiple grounding circuits. The maximum number of conductors (and so of ports for a single cell side) is 26, so enough to represent most network components (the simulation of 6 cables with core, screen and armour requires 18 conductors).
The network components (sources, ideal voltage generators, ideal current generators, loads, transformers, lines, single core and multicores cables, hybrid links, impedances, switches, faults …) are represented with multi-port cells and the connection between cells is obtained by means of multi-port buses. The grounding systems (substation grids, tower footings …) can be specified in an arbitrary way.
NETS calculates parameters of lines and cables starting on data normally available in commercial data sheet. NETS calculates self and mutual impedances and admittance for all conductors using accurate formulas and taking into account the earth resistivity and permittivity.
NETS calculates parameters of single-phase or three-phase two or three-winding transformers starting on data usually available in commercial data sheet.
NETS includes a converter from the sequence domain to the phase domain. This tool can converts a sequence impedances matrix to a phase impedance matrix.
NETS can be used to solve symmetrical or non-symmetric, balanced or unbalanced transmission and distribution networks in steady state or fault conditions.
In particular, NETS can be used for the calculation of the fault current distribution in power networks and between power circuits and earth.
Moreover, NETS is a powerful tool for the evaluation of current distribution and electromagnetic interference in case of railways corridors.
An accurate knowledge of the fault current distribution is crucial in grounding, mitigation to reduce interference on communication circuits and pipelines, power system protections calibration and coordination, neutral grounding resistor sizing and many others applications.
INPUT DATA
- The input data interface has been designed in order to require a minimum and simple set of information
- Circuit Layout (buses and cells distribution and connection)
- Data for generic cells (e.g. cell class, cell type, ports numbers, and for each port, phase from A to Z and parameters like voltages, currents and impedances)
- Data for line and/or cable cells (as a generic cell and in addition, line or cable length, earth resistivity, operative temperature and, for each port, library code and cross section layout information). Line library and cable library include all additional data required by line and cable cells
- Data for transformer cells (as a generic cell and in addition, library code, neutral impedances, and for each port, longitudinal impedances). Transformers libraries include all additional data required by a cell two or three-windings transformer
OUTPUT RESULTS
- Current on each port of each cell
- Current to earth in each connection to earth
- Potential on each port of each cell.
- Potential in each connection to earth
- Power flow on each port of each cell.
- Current distribution along lines and cables
- Potential distribution along lines and cables
- EMF distribution along lines and cables
- Results are available in numerical ad graphical form.
MAIN FEATURES
- Calculation model based on the phase components method and graphs theory for multi-conductor and multi-phase systems
- Automatic debug of data before calculation
- Automatic recognition of the connections between cells and buses and automatic definition of linkage (or boundary) equations
- Arbitrary number of buses and cells (the number is limited only by the hardware constraints)
- Cells class 1: multi-port cells with only a group of ports (input) used to represent sources, ideal voltages or currents sources, transverse impedances or faults
- Cells class 2: multi-port cells with two group of ports (input and output) used to represent overhead lines, overhead or underground single core and multicores cables, hybrid links, two-windings transformers, longitudinal impedances or switches
- Cells class 3: multi-port cells with three group of ports (input and two output) used to represent three-windings transformers
- Buses: multi-port buses with an arbitrary number of group of ports
- Automatic calculation of cables, lines and transformers parameters
- Cable cells can represent single core or pipe type cables. Each single cable can includes core, screen and armour
- A single cell can represent a long line or a long cable or a single span or part of it. The detail level in the model can be decided by the User
- Two-winding transformer cells can represents single-phase or three-phase two-winding transformers. Three-phase transformers can have connections Y, D or Z, any group number (0 to 11), any kind of neutral state (insulated, grounded, and generally grounded with an impedance to earth) and neutral distributed or not
- Three-winding transformer cells can represents single-phase or three-phase three-winding transformers. Three-phase transformers can have connections Y or D, any group number (0 to 11), any kind of neutral state (insulated, grounded, and generally grounded with an impedance to earth) and neutral distributed or not
- Longitudinal impedance cells can represent interruptions of all or single phases
- Transversal impedances cells can represent any kind of short circuit between phases and/or to earth
- The phase impedances necessary to represent components like sources, longitudinal or transverse impedances can be calculated starting from the corresponding sequence impedances matrix using the sequence to phase converter tool
- Libraries with commercial data for lines, single core and multicores cables, conductors and transformers
- Possibility to choose the language (English, German. French, Italian, Spanish, Portuguese)
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