Open Source Real-Time Power System Simulator with HIL
par Lotfi BAGHLI

Introduction

This page presents the open source RTS that we developped for dSPACE Boards DS1103 and DS1104.
It allows the RT simulation of transient stability on small networks with Hardware In the Loop (HIL) capabilities. We can then connect hardware componennts like motors, generators, loads, circuit breakers... to the RTS and study the behaviour of the power network.
This is an academic project and is freely available under GPL licence.

The project begins at the GREEN laboratory at Faculté des Sciences, Nancy Université, Nancy, France
and continues at Faculté des Sciences de l'Ingénieur, Université Aboubakr Belkaeid, Tlemcen, Algeria.
Full programs are available.

Requirements

You need a proper installation of dSpace DS1103 or DS1104 board with CPP compiler. It is a C++ extension of the Microtec C compiler for the PowerPC of the board (c:\PPCTools33).
In order to interface with the HIL environement, you need an inverter and proper electrical interfaces to drive a motor or a R / L load.

Presentation

We will present three examples on the use of this RTS.
We suppose that you are familiar with load flow and transient stability studies on power systems.
Pleas refer to [7],[8],[9],[15],[16] for a comprehensive course on this subject.

Our open source RTS runs on dSPACE single DSP boards (DS1103 and 1104) and uses the abilty of driving PWM signals to control a voltage fed inverter and therefore many actuators, generators, motors and static loads.
This is called HIL (Hardware In the Loop).


First example, RTS without HIL:

The RT simulations are carried for simplicity on a 5-buses well known power network [9]:


We will apply a 3-phases short circuit fault for 0.1 s on bus South:




The simulation can be carried off-line, using a software we develeopped called Power Designer [7]:


Traditional off-line simulation of transient stability for a 3-phases short circuit fault on bus SOUTH



And it can be carried on-line, using the Open Source Real-Time Power System Simulator on the dSPACE board:

Real-Time simulation (on dSPACE DS1104) of transient stability for a 3-phases short circuit fault on bus SOUTH

As we notice, both result are the same.
whereas, in the case of RTS, the transient stability (TS) algorithm is performed on-line, synchronously, every 1 ms.
The software also runs, at the same time, a vector control of an Induction Machine (Double Star) at 10 kHz PWM swithing.

Second example, RTS with HIL:

We present a sudden load increase, done by connecting then disconnecting a Resistance load on the inverter (see below):


The experimental test bench for a HIL real-time power system simulator.

Here are transient stability experimental results of the sudden external load increase:


The external load admittance

The actual external current

The generators speed

The actual external load voltage

The bus voltage

The generated power


As we notice from the previous graphs, the load change is not enough to get the power system lose its stability, but the generators speed is affected.
Without a speed controller, the system can not recover its nominal speed. So, we have to introduce the Power System Stabilizers.

Third example, RTS with HIL and PSS (Power System Stabilizer):

We introduce PSS in order to allow a study for many periods and not only for a "first swing" stability study.
Therefore, the mecanical power is used to control speed and the Eg (Field e.m.f. magnitude) is used to control the voltage. This is the actual system used in the power plants.
The available programms includes this features.

The example bresented below is a 3-phases short circuit fault of 0.1 s on bus South.
This time, the PSS is operating and acts on the Eg magnitude and on the Pm (mecanical power) that drives the generator:




The generators speed

The generators Eg phase

The bus voltage

The generated power


Comparing to the first example (without PSS), this fault is well handled and the network recovers its frequency and voltage in few cycles.
The Controllers gains have to be well tuned to obtain better disturbance rejection. We can use PSO or genetic algorithm to find optimal gains of the controlers. All the studies are carried online on the dSPACE board.


Futur works:

We started the test of a superconducor limiter that is used to limit the current in case of a short circuit.
The main advantage is a reduction of the size and power of the circuit breaker to be installed on the power system.

We have to optimize and reduce the sampling period for the transient stability algoritm (for these examples: 1ms) in order to render the instantaneous voltage instead of working on magnitude and angle of the phasers for the power system. The vector control is already done at asampling period of 200 us for current control loops.
The DSP power of the DS1103 (750 MHz instead of 250 MHz for the DS1104) will be used for that.

We also plan to test the system on a real synchronous generator or on a induction generator running under vector control.
Possibilities are numerous.
If you own a dSPACE board with its C++ compiler, give it a try and send us your feedback.


References

[1]L-F. Pak, V. Dinavahi, G. Chang, M.Steurer, P.F. Ribeiro, “Real-Time Digital Time-Varying Harmonic Modeling and Simulation Techniques,” IEEE Transactions on Power Delivery, Volume 22, Issue 2, April 2007 pp. 1218 - 1227, available online http://dx.doi.org/10.1109/TPWRD.2007.893618
[2]S. Suryanarayanan, W. Ren, M. Steurer, P.F. Ribeiro and G. T. Heydt, “A real-time controller concept demonstration for distributed generation interconnection,” IEEE Power Engineering Society General Meeting, Montreal 18-22 June 2006, pp3, available online http://dx.doi.org/10.1109/PES.2006.1708926
[3]R. J. Marttila, E. P. Dick, D. Fischer and C. S. Mulkins, “Closed-loop testing with the real-time digital power system simulator,” Electric Power Systems Research, Volume 36, Issue 3, March 1996, Pages 181-190, available online http://dx.doi.org/10.1016/0378-7796(95)01030-0
[4]S. Karimi, P. Poure and S. Saadate , “FPGA-based fully digital fast power switch fault detection and compensation for three-phase shunt active filters,” Electric Power Systems Research, Volume 78, Issue 11, November 2008, Pages 1933-1940, available online http://dx.doi.org/10.1016/j.epsr.2008.03.023
[5]B. Lu, X. Wu, H. Figueroa, A. Monti, “A Low-Cost Real-Time Hardware-in-the-Loop Testing Approach of Power Electronics Controls,” IEEE Transactions on Industrial Electronics, April 2007, Volume : 54, Issue 5, pp. 919-931, available online http://dx.doi.org/10.1109/TIE.2007.892253
[6]George G. Karady and Jun Gu, “Employing reprogrammable analog VLSI in real-time analysis of transient stability,” Electric Power Systems Research, Volume 77, Issue 8, June 2007, Pages 980-988, available online http://dx.doi.org/10.1016/j.epsr.2006.08.024
[7]L. Baghli, “Réalisation d'un Environnement Graphique avec Base de Données pour l'Analyse et la Simulation de Réseaux Electriques,” FDP, pp. 123, June 1994, available online http://www.baghli.com/dl/pfe_baghli.pdf
[8]Stevenson, W.D.Jr., “Elements of Power System Analysis,” Mc Graw Hill, 4th edition, 1982
[9]Stagg, G.W. and El-Abiad, A.h., “Computer Methods in Power System Analysis,” Mc Graw Hill, 1968
[10]C. Schacherer, J. Langston, M. Steurer, M. Noe, “Power Hardware-in-the-Loop Testing of a YBCO Coated Conductor Fault Current Limiting Module,” ASC2008, 1LPG05, pp 5, Chicago, August 17 - 22, 2008
[11]J.H. Kim, M. Park, M.H. Ali, A.R. Kim, S.R. Lee, J.Y. Yoon, J. Cho, K.D. Sim, S.H. Kim and I.K. Yu, “A SFCL modeling and application with real HTS material connecting to real time simulator,” Physica C: Superconductivity, Volume 468, Issues 15-20, 15 September 2008, Pages 2067-2071, available online http://dx.doi.org/10.1016/j.physc.2008.05.128
[12]K. Marouani, L. Baghli, D. Hadiouche, A. Kheloui, and A. Rezzoug, “Discontinuous SVPWM techniques for double star induction motor drive control,” in Proc. IEEE IECON, Paris, France, pp. 902-907, Nov. 6-10, 2006, available online http://dx.doi.org/10.1109/IECON.2006.347288
[13]K. Marouani, L. Baghli, D. Hadiouche, A. Kheloui, and A. Rezzoug, “A New PWM Strategy Based on a 24-Sector Vector Space Decomposition for a Six-Phase VSI-Fed Dual Stator Induction Motor,” IEEE Transactions on Industrial Electronics, Volume 55, Issue 5, May 2008 pp. 1910 - 1920, available online http://dx.doi.org/10.1109/TIE.2008.918486
[14]“TMS320F/C240 DSP controllers reference guide, peripheral and specific devices,” Texas Instruments, Dallas, TX, Literature Number SPRU161C, 1999, available online http://focus.ti.com/lit/ug/spru161d/spru161d.pdf
[15]Arrillaga, J. and Arnold, C.P., “Computer Analysis of Power Systems,” John Wiley & Sons, 1994
[16]B. Stott, and O. Alsac, “Fast Decoupled Load Flow,” IEEE Transactions on Power Apparatus and Systems PAS-93, May 1974, pp. 859-869, available online http://dx.doi.org/10.1109/TPAS.1974.293985
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Mise à jour : 27/02/2010