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US-Africa Research and Education Collaboration Workshop

This workshop in Abuja, Nigeria focuses on research projects in power systems, renewable energy, environmental simulation, computer and process control, telecommunications and informatics.

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US-Africa Research and Education Collaboration Workshop

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  1. Third NSF Workshop on US-Africa Research and Education CollaborationAbuja, Nigeria, December 13-15, 2004 Professors John Ngundam and Emmanuel Tanyi of Ecole Polytechnique, University of Yaounde I Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004

  2. STRUCTURE OF THE AUTOMATION AND CONTROL LABORATORY (ACL) • Laboratory Director: Professor John M. Ngundam • Power Systems, Renewable Energy and Environmental Simulation • Group Leader: John Ngundam (Professor) • COMPUTER AND PROCESS CONTROL • Group Leader: Emmanuel B. Tanyi (Associate Professor) • Telecommunications and Informatics • Group Leader: Ndeh Ning, PhD • Center for Health Technology • F. Sop Boyom, PhD Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 John M. Ngundam

  3. RESEARCH PROJECTS IN PROGRESS • Power Systems, Renewable Energy & Environmental Simulation With 294 TWh of industrial scale hydro electricity resources and an enormous potential for small scale hydro electricity production for rural and remote area electrification, Cameroon is still a country with very low access rates to electricity. At the present time, only 7639 GWh a year of this potential is being produced to serve a population of 20 million not to mention export possibilities. Present research effort is directed towards the following: • Generation and Network Expansion Planning • Electricity for Rural Electrification from Renewable Energy Sources • Water Resource Modelling and Management • Load Forecasting • Electricity Markets (very recent addition) • Analysis of Transients in Networks Several long-, medium- and short-term generation planning software packages are being tested or nearing final development. Systems dynamics methods are being introduced in modelling water flows for use in developing large hydro plants and low voltage networks based on renewable energy sources. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 John M. Ngundam

  4. RESEARCH PROJECTS IN PROGRESS CONTINUED • COMPUTER AND PROCESS CONTROL Research into the electric system expansion and development of low voltage transformer free rural networks based on renewable energy have led to a need to develop system control technologies appropriate for controlling this and other systems. On going projects include: • Multivariate Control of the Southern network of the Cameroon Power System • State SPACE Control of the Songloulou Power Generation Station • Microprocessor based Control of the Medium and Low Voltage Transmission Sytems of the Southern Network • Analysis of Pertubations in the Southern Network of the Cameroonian System Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 John M. Ngundam

  5. RESEARCH PROJECTS IN PROGRESS CONTINUED • Telecommunications and Informatics • Design and analysis of optimum and suboptimum receivers for signal detection in non-Gaussian noise • Application of self-critical statistical methods to signal detection. Information and communication technologies and society: governance,Sovereignty, digital divide • Computer and communication networks • Power line communication Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 John M. Ngundam

  6. REPORTS ON SELECTED PROJECTS • DIGITAL INFORMATION TRANSMISSION ON ELECTRIC POWERLINES • COMPUTER AND PROCESS CONTROL Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 John M. Ngundam

  7. DATA TRANSMISSION OVERPOWER LINES BY MODIFICATION OF THE POWER WAVEFORM • INTRODUCTION • VOLTAGE SUPPRESSION AFTER ZERO- CROSSING (VSZC)TECHNOLOGY • MATHEMATICAL MODEL OF THE TECHNOLOGY • ERROR PROBABILITY CONSIDERATIONS • LABORATORY RESULTS • PERSPECTIVES Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  8. DIGITAL INFORMATION TRANSMISSION ON ELECTRIC POWER LINES The power waveform is modified after a defined duration , after the zero-crossing. Technology demonstrated for transmission of signals for controlling (i.e. turning of and on) of devices connected to low voltage (220 V ) electric network and for remote meter reading. In the Voltage suppression After zero-crossing (VSZC) technology, a bit “1” is assumed transmitted when suppression occurs and bit “0” when there is no suppression. Suppression time , is a critical parameter which determines the spectral distribution of the power signal and determines the error probability performance of the system. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  9. VOLTAGE SUPPRESSION AFTER ZERO-CROSSING (VSZC) TECHNOLOGY In VSZC technology, a bit “1” is assumed transmitted when suppression occurs and a bit “0” when there is no suppression. Suppression time , is a critical parameter which determines the spectral distribution of the power signal and determines the error probability performance of the system Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  10. MATHEMATICAL MODEL Modified signal: f(t) = AoSin (ωot) u(t), (1) where u(t) is the unit step function defined as:   1 t > 0 (2) u(t) =  0 t < 0 Without loss of generality, we analyse a single half period of the signal by adding an identical wave shifted version by T/2 (i.e. f(t) + f(t+T/2) to obtain. f1(t) = f(t) + f(t+T/2) = Ao Sin(ot)u(t) +AoSin(o(t-T/2)u(t-T/2) (3) Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  11. MATHEMATICAL MODEL CONTINUED fTrans(t) = Ao Sin(ot)u(t - ) +AoSin(o(t-T/2)u(t-T/2) (4) where ftrans(t) is the information signal propagated down the line. Modification power signal results in harmonics which alter the supplied energy is altered. The energy of the modified signal is given by [1], as Em = A2o (T/4) [ 1 - 2/T + 1/(o T) Sin(2o ) ] (5) Higher harmonics do not appear at suppression. Optimum value of the suppression time is obtained from :   1 - 2/T + 1/(o T) Sin(2o )  0 (6) An iterative solution of (6) gives 1.2 <  < 2.55 (7) In this technology, a value of  = 1.6 ms was used. This value of also satisfied the utility energy supply because it does not drop to less than 90% of the generated value. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  12. MODIFIED POWER SIGNAL Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  13. ERROR PROBABILITY CONSIDERATIONS Transmission error is crucial to the success of the technology. Let the transmission of bits “1” and “0” as:   S1(t) = Ao Sin(ot)u(t - ) +AoSin(o(t-T/2)u(t-T/2) (8)   S0(t) = Ao Sin(ot)u(t) +AoSin(o(t-T/2)u(t-T/2) (9) The probability performance of the system in terms of the error function Q(*), is given as:  Q() = Q{(Ev/No (2 - Sin(2) / (4 - 2 + Sin()}1/2 (10) where Ev is the average signal energy and No is obtained from the noise waveform possesing a Gaussian probability density function and a double –sided power spectral density. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  14. LABORATORY RESULTS • TESTS CONDUCTED • Remote control of various loads from a single point • Transfer of text between two computers • Adaptation of a standard utility meter for for electronic display and remote reading using the scheme. Inbound and outbound communications are possible provided the targets are within a radius of between 5 and 8 kilometers. If these distances are exceeded, detectability becomes a problem. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  15. PERSPECTIVES • Present investigations include include: • Generation and load management for rural and remote stand alone • electric systems without transformers. The radius of operation is • limited to distances between 5 and 8 kilometres. This is ideal for rural • settings in places like Cameroon. • Remote meter reading and text transmission. • Interfacing high speed data signals such as the INTERNET, • Real time transmission of TV signals and voice communications on • the power line, through the uses of compression techniques, powerline • MODEMS, etc Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 J.M. Ngundam

  16. MULTIVARIATE CONTROL OF THE SOUTHERN NETWORK OF THE CAMEROONIAN POWER SYSTEM • - INTRODUCTION • - DEVELOPMENT OF A MULTIVARIATE MODEL • - DESIGN OF A MULTIVARIATE CONTROL SYSTEM • - PERSPECTIVES Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  17. INTRODUCTION Capacity of the Power System • 805.7 MW • Dominance of Hydro Stations : 720 MW (89.4 %) • 3 Hydro Stations : • - Edea (264 MW); • - Songloulou (384 MW); • - Lagdo (72 MW)Structure of the Power SystemNational Power System Organised into 2 Autonomous Networks : • Southern Network (Edea; Songloulou ) • Northern Network ( Lagdo ) Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  18. Fig. 1 : Northern and Southern Networks of the Cameroonian Power Network Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  19. Fig. 2 : Southern Grid of the Cameroonian Power Network Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  20. PROBLEMS WITH THE SYSTEM Supply far below demand = Frequent Load shedding This situation is due to many problems :Ø      Obsolescence of equipment (Edea, 1953)Ø      Inefficient Control StrategiesØ      Industrial ExpansionØ      Galloping Population ExpansionØ      Decrease in the level of the Sanaga RiverØ      Silting of the Dams Situation requires a combination of many solutions. Ø One solution is the design of more efficient control strategies. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  21. DEVELOPMENT OF A MULTIVARIATE MODEL • Hydro Generating Stations • We have developed a system of 14 equations for each of the generating stations • Flux Linkages due to Self and Mutual Inductances of the Rotor and Stator: Notation : 1, 2, 3 refer to phases while the subscripts ‘r’ and ‘s’ refer to the rotor and stator. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  22. Voltage Equations for the Rotor and Stator Circuits : Electro-mechanical Equations ( Torque Equations ) : Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  23. TRANSMISSION SYSTEM • The transmission System is modelled as 5 subsystems :- • High Voltage Lines (225 KV) • Medium Voltage Lines (90 KV) • Low Voltage Lines (220V) • Medium Voltage Station • Low Voltage Station The Medium Voltage Station Steps down the voltage from 225kV to 90 kV The Low Voltage Station Steps down the Voltage from 90 KV to 220 V. Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  24. 225 KV Line Medium Voltage Station 90 KV Line Low Voltage Station 220 V Line FIG. 3: COMPONENTS OF THE TRANSMISSION SYSTEM Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  25. DESIGN OF A MULTIVARIATE CONTROL SYSTEM • Configuration of the Control System : • A Distributed Control System incorporating 4 • Multivariate Control Stations : • - Edea Generation Station • - Songloulou Generating Station • - Medium Voltage Transmission Station • - Low Voltage Transmission Station Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  26. Edea Control Station (Hydro Station) Medium Voltage Transmission Station Low Voltage Transmission Station Sondloulou Control Station(Hydro Station ) FIG. 4 : ARCHITECTURE OF THE DISTRIBUTED CONTROL SYSTEM Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  27. CONTROLLER DESIGN STRATEGIES • 3 Stategies : • Inverse Nyquist Array : • · Use MATLAB to Calculate Multivariate Transfer Function • · Write Software to Calculate Inverse Transfer Function • · Analyse Diagonal or Row Dominance • · Calculate Parameters of the Controller • Dyadic Control (Eigenvalue-based Design ) • Calculate Eigenvalues of Multivariate Transfer Function (MATLAB) • Calculate Parameters of Dyadic Controller Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  28. CONTROLLER DESIGN STRATEGIES cont. • First Order Approximation Method • · Simulate Closed-Loop System (without Controller) to generate Time Response Curves • · Derive Approximate First Order Models from the Time Response Data • · Calculate the Parameters of the Controller Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  29. PERSPECTIVES • The modelling aspect of the project is fairly complete, but Control Systems Design aspect is still in progess. This involves four Aspects :- • - Inverse Nyquist Array Controller • - Dyadic Controller • - First Order Approximation Controller • - Evaluation of the Performance of the Controllers (MATLAB Simulation ) Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  30. INFORMATION TECHNOLOGY • Real-time Applications for Control of Power Networks • Object-Oriented Modelling of Automatic Control Systems • Simulation of Hybrid Control Systems Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  31. REAL-TIME APPLICATIONS FOR CONTROL OF POWER NETWORKS • 8 themes under Exploration : 1. Multi-tasking Operating Systems for Foreground- Background Control tasks 2. Implementation of Packages in JAVA and C++ 3. Concurrent Execution of Packages using the technique of Multi-threading 4. Real-time Interface for Power System Control 5. Algorithms for the Implementation of State Observers 6. Digital Filters 7. Client-server Applications in Control 8. Communication Protocols for Real-time Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  32. OBJECT-ORIENTED MODELLING OF AUTOMATIC CONTROL SYSTEMS • Application of the Unified Modelling Language (UML) to Automatic Control Systems: • Discrete Systems : • - Class hierarchies for Grafcet (Function Chart) Objects • - Interactive Grafcet Construction • - Inference Engine for Grafcet Execution • - Class hierarchies for Petri Net Objects • - Interactive Petri Net Construction • - Inference Engine for Petri Net Execution • Continuous Systems : • Class Hierarchies for Equations • Objects for Block Diagram Construction Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  33. (package) (package) SYSTEM SEQUENTIEL GRAFCET 0 .. * Est décrit par 1 RECVENSYS RECEPTIVITE LOGIQUE Appartient à RECEPTIVITE TEMPORELLE RECEPTIVITE GRAFCET 1 .. * Conditionne 1 .. * 1 .. * 0 .. 1 0 .. 1 1 .. * ETAPE TRANSITION 1 1 .. * 0 .. * 0 .. * MACRO-ACTION Décrit LIEN COUPLAGE SEQ 1 .. * LIEN ACTION SIMPLE LSAUT ETAPE ACTION LIEN EXCLUSIF ACTDIRSYS LIEN SELECTIF ACTION DETAILLEE LIEN PARALLELE ACTION MULTIPLE LIEN SIMPLE FIG. 5 : OBJECTS HIERARCHY FOR THE GRAFCET PARADIGM Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  34. SIMULATION OF HYBRID CONTROL SYSTEMS • Development of a Repertoire of Object Classes for Simulation of Sequential systems • Development of a Repertoire of Object Classes for Simulation of Continuous Systems • Modelling of Interactions between continuous and Discrete Components of a Hybrid System • Development of Continuous and Discrete Simulators • Concurrent Execution of the Two Simulators using Multi-threading • Application to Rolling Mill • Application to Power Systems ( Scheduling + Control) Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

  35. FIG. 6 : HYBRID SIMULATION OF ROLLING MILL Third US-Africa Research and Education Collaboration Workshop Abuja, Nigeria, December 13-15, 2004 Emmanuel B. Tanyi

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