MOC

As a hydropower enginner, I used MOC equations (programmed in python) to perform Transient Analysis. Contents Technical Documentation — Version 6.0.0 1. Introduction 1.1 What the software does 1.2 Why this matters 1.3 What the software can and cannot do 1.4 The reference model used in this document 2. Water hammer and surge in plain words 2.1 Water hammer 2.2 Negative pressures 2.3 Surge (mass oscillation) 2.4 Load rejection and load acceptance 2.5 Why the Method of Characteristics 3. Software overview 3.1 Architecture 3.2 Data flow 3.3 Installation and start 3.4 Using the engine without the window 3.5 Version 6 in one paragraph 4. The mathematics 4.1 The two equations of unsteady pipe flow 4.2 Characteristic equations 4.3 Wave speed 4.4 Friction 4.5 Non-circular tunnels 4.6 Effective area of an inclined surge pipe 4.7 Pressure from head 5. The numerical method 5.1 The grid 5.2 Automatic time-step reduction 5.3 One time step in eight actions 5.4 Surge level update 5.5 How accurate is the time step? (grid convergence) 6. Component and boundary-condition models 6.1 Reservoirs 6.2 Pipes 6.3 Pipe junction (bend, change of diameter, minor loss) 6.4 Surge chamber 6.5 Manifold 6.6 Turbine 6.7 Tailrace 6.8 Valve 7. Gate events and initial conditions 7.1 Gate opening τ(t) 7.2 Why the initial state matters 7.3 How the initial state is built 7.4 Partial-gate events start in equilibrium 7.5 Automatic steady-state check 8. Input reference 8.1 Order of components 8.2 Reservoirs 8.3 Pipe 8.4 Pipe junction 8.5 Surge chamber 8.6 Manifold 8.7 Turbine 8.8 Valve 8.9 Simulation settings 8.10 How long should the simulation be? 9. Output reference 9.1 Time series 9.2 Spatial results 9.3 Component analysis (per pipe) 9.4 Messages 9.5 Files you can export from the window 10. User guide 10.1 The window 10.2 Step-by-step workflow 10.3 What the run buttons do 10.4 Reading the plots 10.5 Exports 10.6 Good habits 10.7 Common mistakes 11. Worked example: the reference model 11.1 Setting up 11.2 Initial state 11.3 Component analysis 11.4 Load rejection 11.5 Load acceptance 11.6 Worst-case envelope 11.7 Head against time at selected points 11.8 What the results tell the designer 12. Sensitivity studies 12.1 Orifice diameter 12.2 Closing time 12.3 Tunnel wave speed 12.4 Time step 12.5 A short list of design hints from the studies 13. Verification and validation 13.1 Steady state before the event 13.2 Joukowsky check 13.3 Surge period 13.4 Thoma stability check 13.5 The version 5 defect: before and after 13.6 Built-in presets 13.7 What is not validated 13.8 Regression test 14. Assumptions, limitations and good practice 14.1 Physical assumptions 14.2 Software limitations 14.3 Checklist before you trust a result 14.4 Troubleshooting 14.5 Planned improvements (suggestions) Appendix A. Nomenclature Appendix B. Glossary Appendix C. Reference configuration (JSON) Appendix D. Result dictionary keys Appendix E. Change log, version 5 → version 6 Appendix F. Quick-start cheat sheet Appendix G. References 1. Introduction 1.1 What the software does Hydropower plants move a lot of water through long tunnels and pipes. When the turbine gate moves quickly, the water cannot stop or start at once. This creates two kinds of fast changes: ...