The NEPLAN Dynamic Simulator offers an extensive and detailed set of models for all the power system elements. An extensive library of controller models is available, including exciters, turbines, PSSs, converter controllers, etc. The NEPLAN Dynamic Simulator can handle in a unique mathematical system a hybrid model formulation: combination of AC and DC networks can be easily simulated all together, including HVDC systems, DC-lines and several DC elements (batteries, photovoltaic panels, fuel cells). All the models are described in the Differential Switched-Algebraic State Reset Equations structure, called DSAR.

The flexible environment of NEPLAN Dynamic Simulator offers also excellent functionalities to develop user defined models. For each element it is possible to build a user defined model by one of the following three approaches:

• function blocks (graphic oriented)
• user defined DLL (automatically created from symdef files)
• interface with Matlab/Simulink®

Especially for researchers and developers, the flexibility in creating user defined component models could be very useful for several aspects:

• dynamic models for special machines or loads
• non-standard controller schemes
• wind power systems or FACTS devices
• wide area network controllers
• detailed model of protection devices

Moreover, all the functionalities of  NEPLAN Dynamic Simulator can be accessed by a C/C++ API, the NEPLAN Programming Library (NPL).

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This module computes the motor start-up in unlimited networks and offers the possibility of simultaneous or time-delayed start-up for any desired number of motors. Motor Starting module can simulate different motor models, depending on the motor data entered and it also allows for start-up devices, such as star-delta starter, series resistor, transformer, soft starter, etc.

General Characteristics

• Identification of motor parameters using the least square method from input values for torque, current and cos(phi) in function of the slip
• Saturation and eddy-current losses in the motor allowed for (linear or point-by-point)
• Libraries for standard motor data, plus additional extendable libraries for Me(s), I(s) and cosphi(s) are available
• Operating point computation for all non-starting motors in accordance with their load characteristics (Newton-Raphson)
• Automatic tap changing transformers are allowed for after a user-defined time-delay
• Load torque entered as a characteristic or as a linear or quadratic load torque curve
• Extendable Libraries for load torques are available

Voltage Drop

This option calculates the voltage drop at time t=0.0 due to starting motors, thus less motor data and computation parameters have to be entered. Non-starting motors can be simulated by a user-defined load PQ (constant power) or shunt. Results of Voltage Drop Calculation are easily accessible:

• Overloaded elements, measuring instruments and protective devices or nodes with voltages outside a defined range are highlighted
• Results of the voltage drop computation are displayed in the single line diagram
• The motor data entered and the motor parameters computed can be accessed by clicking on the motor concerned in the single line diagram

Results

Results contain information on preselected nodes and elements. Also, graphical output of the characteristic curves and time characteristics is provided. Results display (dimensioning, scaling, colors etc.) can be customized.

• Computation of voltage U(t) at predefined nodes and of l(t), P(t), Q(t) for predefined elements
• Computation of motor current I, load torque M, electromagnetic torque Me, active power P and reactive power Q as functions of time, or of the slip for starting-up and non-starting-up motors
• Result lists can be saved in text files
• Results can be saved in result files for evaluation by means of spreadsheet programs (such as MS-Excel)

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Optimal Power Flow (OPF) module calculates the control variable settings and the network state (complex variables, line currents) that optimize the objective set by the user. Objective is usually the minimization of the active power losses or the minimization of the total generation costs. OPF can be extended to the Contingency Constrained OPF (CC-OPF) that ensures N-1 system operating security. CC-OPf delivers a network state that is optimal in terms of a user-defined objective, satisfies all operating and control constraints and additionally satisfies all the network power balance equations for every single element or node failure.

General Characteristics

• Control variables: active / reactive power generation, schedule voltages of generators and taps of ULTC-transformers, reference values of HVDC systems and FACTS (UPFC, STATCOM, SVC, TCSC)
• Variable limits for bus voltages, branch loadings, active and reactive power of generators
• Individual or general limits, ’consider/not consider’ limits function
• Objective function: apply to whole network / to a certain area or zone, minimize / maximize MW losses, Mvar losses, generation cost, MW import or Mvar import, MW Interface flow
• Multi-objective function is possible (use of weighting factors)
• Security constrained optimization (with N-1 contingency constraints)

Results

Upon calculation results are automatically displayed on the single line diagram while their content and graphical information can be customized. Result evaluation and processing is easier due to visualization functions:

• Optimization results: binding constraints, variables at limits, lambda multipliers, sensitivities, network controls, colouring of limiting network elements in the graphic
• Overloaded elements or nodes with voltages outside predefined limits are highlighted
• Line thickness corresponds to element loading
• Results can be saved in a text file (ASCII)
• Table output: for the whole network, individually for each area / zone. Listing of power flows between area/zones, overloaded elements, sorting function, selective output
• Table interface with MS-Excel

NEPLAN Programming Library – NPL is a C/C++ API library, which allows user to access NEPLAN data and calculation engines to develop customized calculation algorithms through a C/C++ program. The compiler used for creating the C/C++ program, which is a dynamic link library (dll), is MS Visual Studio 2008 and later.

Functions

Some of the basic functions included in the NPL are

• Access and change any variable of any component
• Execution of any analysis/calculation function
• Adding and deleting components of the network and manipulating their graphical information (coordinates, symbols, etc.)

Applications

NPL gives user the freedom to build solutions addressing personalized needs. Among the numerous possibilities, common applications of NPL are

• Implementation of NEPLAN in a SmartGrid environment
• Use NEPLAN in batch mode (e.g. running several load flows and short circuit calculations cases)
• Build customized interfaces (e.g. GIS, SCADA/DMS, DACF, CIM, etc.)
• Develop a network master controller with events (such as “if u <90% switch on reserve generator”) and run the application in a quasi stationary mode
• Checking protection behavior under various network conditions
• Use NEPLAN as server and connect NEPLAN to a TCP/IP bus. The client may send any NPL command to the NEPLAN server (e.g. run load flow, open switch, change load, etc.)
• Use NEPLAN as on-line system and build a DMS application using the NEPLAN graphic editor and the analysis tools
• Develop customized calculation algorithms (e.g. OPF, reliability, capacitor placement etc.)

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This module calculates the limiting MW transfer value between two control areas (source and sink) that is available without any violation of security limits.

General Characteristics

• ETSO methodology (load flow based, MW generation shift)
• Large flexibility in limit handling (individual activation of limits)
• Consideration of user-defined contingency scenarios
• Consideration of Transmission Reliability Margin (TRM )

Results

The outcome of the calculation is a list of the limit violations for every step of increasing the MW transfer from source to sink as for

• the base case
• each contingency case

The module provides calculation of the Total Transfer Capacity (TTC) and the Net Transfer Capacity (NTC).

Load flow

This module performs Load Flow studies for 3-, 2- and 1-phase AC and DC systems for meshed, looped and radial networks from HV to LV. It includes disperse generation models such as wind power, photovoltaic, small hydro, geothermic, etc. and provides a wide variety of calculation options to address specific applications for symmetrical and asymmetrical systems.

General Characteristics

• Computation methods: Current Iteration, Newton Raphson, Extended Newton Raphson, Voltage Drop (per-phase), DC load flow
• Voltage and flow control with phase-shifting transformers
• HVDC, PWM and FACTS devices, like SVC, STATCOM, TCSC, UPFC
• DC-Batteries, DC-Fuel cells, DC-Voltage source, DC-Photovoltaic panels
• Node types: slack, PQ, PV, PC, SC, PI, IC with intuitive assignment. More than one slack node possible
• Power interchange between area / zones (area interchange control) and distributed slack node
• Predefined and user defined scaling factors for fast load and generation variations
• Measurement data import and load balancing
• Calculation of loss sensitivities (PDTF-factors)
• Powerful convergence control with initialization file input / output
• Limit check and appropriate automatic conversion of the node type

Results

Upon calculation results are automatically displayed on the single line diagram while their content and graphical information can be customized. Result evaluation and processing is easier due to visualization functions:

• Overloaded elements or nodes with voltages outside predefined limits are highlighted
• Line thickness corresponds to element loading
• Table output: for the whole network, individually for each area / zone. Listing of power flows between areas/zones, overloaded elements, sorting function, selective output
• Results can be saved in a text file (ASCII)
• Table interface with MS-Excel

Contingency Analysis

This module allows the user to define all elements and nodes to be disconnected during the contingency analysis. In single mode outage nodes or elements are disconnected one by one and the load flow is calculated. Common mode outages can also be defined to disconnect several nodes and/or several elements at the same time.
Results demonstrate the outaged elements, the value of the variable violating limits and the divergence of this value from the base case in %. The outages are listed in order of decreasing number of voltage and current violations.

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NEPLAN offers an efficient Library Manager that provides extensive libraries for elements of any type while it allows the user to create complementary customized libraries. The comprehensive Library Manager is fully integrated. When inserting network data, the data in the library can be accessed. Furthermore, the data inserted in the network can be exported to the library.

Library Manager provides more than 16’000 embedded library items for practically any element:

• Libraries covering various Standards like IEC, IEEE, ANSI, etc.
• Libraries for all elements
  • Primary elements, such as cables and lines
  • Electrical machines, such as synchronous and asynchronous machines, transformers, motor characteristics
  • Protection elements, such as elements for distance protection and overcurrent relays from various manufacturers (e.g. ABB, SEL, Siemens, Westinghouse, etc.)
  • Fuses from various manufacturers
• Standard Controllers for Dynamic Simulation EMT and RMS
  • All controllers defined in the ENTSO-E CIM standard IEC 61970 for exciters, turbines, PSS, etc.
  • All wind turbine models according to IEC 61400-27-1 (type 1, Type 3, type 3 and type 4)
  • Models for renewables (e.g. batteries)
  • Models for converters (HVDC, voltage source and current source converters, PWM, etc.)
• Load Profile Characteristics, Day Profiles, VDEW Profiles
• Frequncy Dependencies for Harmonic Analysis
• Harmonic Sources (e.g. 6-, 12-, 24-pulse converters)
• Harmonic voltage and current levels according to IEC, VDE, IEEE (e.g. IEC 61000-2-4)
• Investment Data Items for economic calculations

General Characteristics

• All network data can be updated with changed library data
• The data can be entered through excel like table sheets
• Import/export to MS-Excel with drag and drop
• Part of diagrams with all technical data can be stored in the library (e.g. used for IEEE control circuits)

This module enables the user to display a two dimensional profile in a chart of any selected pipes in the network.

General Characteristics and Results

• Copy/Paste to the clipboard for documentation in MS-Word
• Color the selected pipes in the diagram
• The elevation and the absolute pressure is displayed in the chart
• The chart displays the correct proportion of the line length and the elevation
• Export the chart to a *.JPG file for any internet browser

Net present value calculation with NEPLAN is based on two variants: one is the base or pre-investment case and the other the investment case, which is the network with all new components. In the Investment analysis new components and their investment data are evaluated.

General Characteristics

• User-defined participation of elements in the calculation
• Network losses are determined from a load flow calculation for the investment case
• Consideration of load-dependent costs (ohmic losses) and of load-independent costs (magnetization, weather-dependent corona, and dielectric losses)
• Consideration of taxes, maintenance costs, inflation, interest rates, etc.
• Component’s investment data with material item costs are available in libraries

Results

The outcome of the cost analysis in terms of Net Present Value (NPV), Internal Rate of Return (IRR), Pay Back Period (PBP), etc. is displayed. The module provides with additional functions:

• Merging of different investment alternatives
• Comparison against different investment alternatives
• Comparison against the «do-nothing» scenario
• Comparison between investment variants

This basic module enables the user to model, design and optimize his heating network using NEPLANs famous graphical interface and NEPLANs powerful, up-to-date calculation algorithms to address a wide range of applications.

General Characteristics

• Loads (consumers) can be changed through 3 different load factors (general, regional or simultaneity load factors).
• To each pipe any number of line loads can be connected (e.g. houses, heating …). Importing of consumers from existing databases (e.g. from an accounting database) is possible.
• All load and simultaneity factors of the line loads are considered during the calculation.
• The consumptions can be entered in different units (e.g. l/s m3/h, kW, t/h, etc).
• Simultaneous calculation of multiple partial networks (independent networks).
• Calculation of heat exchanger, heat plant, centrifugal and circulation pumps, reservoirs, valves, fittings, pressure regulators, etc.
• All elements have a temperature dependent thermo hydraulic model.
• It is possible to calculate only the forward flow. The return network must not be entered.
• It is possible to enter also the return network and calculate the forward and return network together.
• The calculation can be done without temperature losses. This can help to debug the network model.
• A powerful up-to-date calculation algorithm (Extended Newton Raphson) is implemented. This allows very easily inserting new element models. The complexity of the models is no longer restricted.
• The head loss characteristics of the pipes are calculated according to Prandtl-Colebrook and Hagen-Poiseuille.
• A load library (household, industrial loads …) with different simultaneity factors can be defined.
• Sophisticated pump and valve models, which allows regulating pressure, flow, pressure differences at any node or element.

Results

Upon calculations, results are automatically displayed on the single line diagram while their content and graphical information can be customized. Result evaluation and processing is easier due to visualization functions:

• Coloring according to variable ranges (e.g. velocity, flow, pressure-losses, pressure etc.)
• Highlighting of overloaded elements (e.g. velocity v > v max)
• Line width proportionally to many variables, including the flow and diameter
• Result output to an excel like table sheet, with copy/past possibilities to MS-Excel
• Output to ASCII files or SQL database for further evaluation (e.g. MS-Excel)
• Display results in a sophisticated chart manager (e.g. bar or line chart)
• Result boxes can be moved, deleted, sized, colored and hided
• Self-defined result output: the user can select units, variables, font, precision, placement
• Comparing results was never easier: Results from other variants can be displayed in the same result label and in the same chart
• Display the temperature, temperature losses and power losses in the diagram and in excel like table sheet