NRJXpert tutorial

Learn power systems and renewable energy systems, from Ohm's law to the optimisation of a microgrid, by calculating by hand and then checking with the software.
Tutorial Version 2.0.0 November 2026 EN / FR Click for the French version
NRJXpert tutorial
NRJXpert 2.0.0 · November 2026

📘Introduction

Languages. The whole tutorial (levels 1 to 7, case studies, teacher's guide, appendices) is available in English and in French: each page has a link to its other-language version. The software itself is fully available in English (Options › Language).
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📋Who is this tutorial for?

AudienceRecommended pathIndicative duration
Technician (BTS, DUT, professional bachelor), electrician, PV installerLevels 1 and 3 (§ 3.1 to 3.4), level 4 (§ 4.1 and 4.2)40 h
Engineering student (bachelor, master, engineering school)Levels 1 to 4 in full, then level 5 (§ 5.1 and 5.2)80 to 100 h
Design engineer, consulting firmLevels 2, 3 and 4 (methods and assumptions), level 5, case studiesAs needed
Smart grid expert, consultant, owner's engineerLevels 5, 6 and 7, synthesis project and expert assignment60 to 80 h
TeacherTeacher's guide: progressions, lab sessions, marking schemes, subjects—
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📗How to work

  1. Read the theory of each section: definitions, assumptions, equations. The blue boxes recall the formulas to remember.
  2. Do the example by hand (calculator, spreadsheet) before looking at the solution: that is where understanding happens.
  3. Check with NRJXpert in the « Lab » boxes 🛠: draw the diagram or enter the data, run the calculation and compare with the hand calculation. A difference must always be explained (assumption, rounding, model).
  4. Practise with the solved exercises (« Show the solution ») and the calculators 🧮, then answer the quiz at the end of the level.
  5. Vary the data: what happens if the length doubles, if the voltage goes from 24 to 48 V, if the discount rate changes? Habit makes the engineer.
Example files. The projects quoted in the tutorial are in the folder ~/.nrjxpert/aide/tutoriel/exemples/, created when the tutorial is first opened. In NRJXpert, Help › Open a tutorial example… opens each file in the right window: network diagrams .nxp, photovoltaic projects .nxpv, wind projects .nxeol, solar pumping projects .nxpomp. The .xml files are networks as the client sends them to the calculation server: they open in the Calculate a network file (XML) window, where values can be changed before running.
Calculation server. Network calculations (levels 1, 2, 5, 6 and 7, case studies 2 and 3) are performed by the NRJXpert calculation server, hosted remotely: an Internet connection, the server address and the access key supplied with the software are needed (Simulation › Calculation and server settings › Test the connection). Levels 3 and 4 (photovoltaics, wind, economics) work offline.
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📙Conventions

Decimalsthe English pages use the decimal point (2.5 mm²), the French pages the decimal comma (2,5 mm²); the software accepts both Currencycurrency unit chosen by the user (CFA franc by default); “k” = thousand, “M” = million of the chosen unit. In this tutorial, amounts are given in CFA francs (F): kF = 1 000 F; MF = 1 000 000 F. Prices are indicative (2026) AC quantitiesRMS values; three-phase: U line-to-line, V phase-to-neutral, U = √3·V PowerP active (W), Q reactive (var, positive for an inductive load), S apparent (VA) Phasorspolar notation 230∠0° or complex 230 + j0; j² = −1 Standards quotedIEC 60364 (LV installations), IEC 60909-0:2016 (short circuit), IEC 61400-12-1 (wind), IEEE 1547-2018 (DER interconnection), IEEE 2030.7/2030.8 (microgrids), IEC 62056 (DLMS/COSEM), OpenADR 2.0b, IEC 62443 / IEC 62351 (cybersecurity)
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🧩Detailed contents

Level 1 — Fundamentals

  1. Quantities, Ohm's and Kirchhoff's laws
  2. Sinusoidal steady state, impedances, power
  3. Reactive power compensation
  4. Three-phase systems
  5. Getting started with NRJXpert

Level 2 — Power networks

  1. Line and cable models
  2. Transformers
  3. Per-unit system
  4. Voltage drop and losses
  5. Load flow: formulation
  6. Gauss-Seidel, Newton-Raphson, fast decoupled
  7. Short circuit: IEC 60909, symmetrical components
  8. Protection: breaking capacity, selectivity

Level 3 — Renewable energy

  1. Solar resource
  2. The photovoltaic module
  3. Stand-alone PV sizing
  4. Wiring: cross-sections, protection, costs
  5. Grid-connected PV
  6. Wind resource and Weibull distribution
  7. Wind production and sizing
  8. Solar water pumping

Level 4 — Economic studies

  1. Time value of money
  2. Life-cycle and discounted cost
  3. LCOE
  4. NPV, IRR, payback
  5. Minimum tariff and subsidy
  6. Sensitivity and comparison of options

Level 5 — DER and smart grids

  1. Load flow of distribution networks
  2. Controlled inverters and hosting capacity
  3. Time series
  4. Microgrid dynamics
  5. Inverter short circuit
  6. Economic dispatch and OPF
  7. Optimal hybrid sizing

Level 6 — Smart grids: architecture, operation, owner's engineering

  1. SGAM architecture (IEC SRD 63200)
  2. OT/IT operation: SCADA, ADMS, DERMS
  3. Self-healing (FLISR) and reliability
  4. Volt/VAR control (IVVC, IVVC/r, CVR)
  5. Virtual power plants
  6. Microgrids and smart inverters
  7. E-mobility (V1G, V2G)
  8. Data models and protocols
  9. Owner's engineering and project governance
  10. Skills matrix

Level 7 — Expert workshop

  1. Microgrid controller tests (IEEE 2030.7 / 2030.8)
  2. Smart metering: technical and non-technical losses, fraud
  3. DLMS/COSEM data collection, G3-PLC
  4. OpenADR 2.0b demand response
  5. IEC 62443 / IEC 62351 cybersecurity
  6. Expert assignment

Complements

  • Four consulting case studies
  • Teacher's guide: progressions, lab sessions, marking schemes, subjects
  • Appendices: formulas, cable tables, c factors, constants

Tutorial written for NRJXpert — Lamine Thiaw, Electrical Engineering Department, École Supérieure Polytechnique, Université Cheikh Anta Diop de Dakar. The numerical values of the examples were checked with the software.

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👤Author

LT
Prof. Lamine THIAW
Department of Electrical Engineering
École Supérieure Polytechnique
Cheikh Anta Diop University, Dakar
lamine.thiaw@ucad.edu.sn
lamine.thiaw@esp.sn

November 2026