Energy Storage Part 4 pptx

Energy Storage 30 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 -400 -300 -200 -100 0 100 200 300 400 Time (s) Current (A) i d current i q current Fig. 14. PMSM i d and i q currents 1.2 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.3 -400 -300 -200 -100 0 100 200 300 400 Time (s) Current (A) i a current i b current i c current Fig. 15. DSTATCOM i a , i b and i c currents 1.2 1.202 1.204 1.206 1.208 1.21 1.212 1.214 1.216 1.218 1.22 -500 -400 -300 -200 -100 0 100 200 300 400 500 Time (s) Current (A) i a current i b current i c current Fig. 16. PMSM i a , i b and i c currents Control of a DSTATCOM Coupled with a Flywheel Energy Storage System to Improve the Power Quality of a Wind Power System 31 Efficiency and losses of the PMSM Tests were made for different power requirements in the whole range of operation speeds of the machine. The results of the efficiency of the machine for an exchange of power of 10 kW, 50 kW and 100 kW are shown in Fig. 17. In this figure a high efficiency of the PMSM can be observed above 98% when the power is high (50 or 100 % of the rated power), even in the whole speed range. A division of the losses of the PMSM for different requirements of power are shown in Fig. 18. In these figures it can be observed that the mechanical and the iron losses increase with the rotational speed of the machine and they practically do not depend on the exchange power. Moreover, it can be observed that the copper losses depend both, on the rotational speed and on the exchange power. The copper losses have more significant values at low speeds. This is because in order to deliver a certain constant power at low speeds a bigger torque and therefore a bigger current are required. When there is no power transfer, the losses range from 0.3-1.1 kW. 6. Conclusions This paper presents model aspects and control algorithms of a DSTATCOM controller coupled with a High-Speed Flywheel Energy Storage System. A proposal is made of a detailed fully realistic model of the compensator and a novel multi-level control algorithm taking into account three control modes to mitigate problems introduced by wind power in power systems. From the results obtained, it can be concluded that the detailed models and developed control algorithms have worked satisfactorily. With the implemented control, an excellent decoupling is kept in the control of the active and reactive power. Moreover, with the device and control modes proposed, the power fluctuations coming from a WG are effectively compensated. It was shown that the WG-DSTATCOM/FESS system can deliver a constant active power in a time range of seconds or more, depending on the storage capacity. For the reactive power control, it was shown that the system proposed is able to provide a unitary power factor or to obtain a dynamic control of the voltage in the connection point for power disturbances in the WG and also for fluctuations in the system such as sudden variations in the load. Therefore, the incorporation of DSTATCOM/FESS has shown that it can improve the power quality in wind power systems. 90 92 94 96 98 100 15,5 19,375 23,25 27,125 31 Rotor s peed (krpm) Efficiency (%) 10 kW 50 kW 100 kW Fig. 17. Efficiency of the PMSM Energy Storage 32 Fig. 18. Losses of the PMSM for transfer power of: 10kW, 50kW and 100kW 7. APPENDIX A TEST SYSTEM DATA Line data are given in Table 1. Table 2 shows the transformer data. All p.u. quantities are on 13.8 kV and the transformer rated MVA base. Table 3 shows the main parameters of the generation unit coupled to the wind turbine. Table 4 shows the main parameters of the wind turbine and the power curve of the turbine is shown in Fig. 19. All p.u. quantities are on a 690 V and on the 750 kVA base. Finally, the most important load data are shown in Table 5. Control of a DSTATCOM Coupled with a Flywheel Energy Storage System to Improve the Power Quality of a Wind Power System 33 From To U N LR X B bus bus kV km Ω/km μΩ -1 /km L1 2 3 13.8 30 0.01273 0.2933 4 .0024 ID Ω/km Table 1. Line data ID: component identifier; U N : rated voltage; L: line length; R, X and B: positive sequence resistance, reactance and susceptance of sub-transmission line. From To R X Rm Xm S N N p /N s bus bus pu pu pu pu kVA kV/kV T1 5 6 0.002 0.021 500 500 1000 0.69/13.8 ID Table 2. Transformer data R and X: winding resistance and reactance; Rm and Xm: magnetization resistance and reactance; S N : rated power; N p /N s : voltage transformation ratio S N U N Rs Xs Rr Xr H kVA V pu pu pu pu s WG 5 Induction Squirrel-cage 750 690 0.016 0.06 0.016 0.06 0.095 2 p Machine RotorID Bus Table 3. Wind generator data Rs and Xs: stator resistance and reactance; Rr and Xr: rotor resistance and reactance; H: inertia constant; p: pairs of poles H Wc-i Wc-o Wrp sm/sm/s m/s WT 2 4 25 16 ID Table 4. Wind turbine data Wc-i: cut-in wind speed; Wc-o: cut-out wind speed; Wrp: rated wind speed 0 250 500 750 1000 0 5 10 15 20 25 3 0 Wind speed (m/s) Power (kW) Fig. 19. Power curve of the wind turbine Energy Storage 34 P L Q L kW kvar Ld1 4 300 0 Ld2 4 700 0 ID Bus Table 5. Load data P L and Q L : load real and reactive power. 8. Appendix B DSTATCOM/FESS controller data Tables 6-8 summarize the most important data corresponding to the FESS, Interface and DSTATCOM subsystems. P max Et d S min S max J U d kW Wh s krpm krpm kg m² V FW 100 750 27 15.5 31 0.72 750 General ID Table 6. FESS data P max : maximum rated real power; E: rated storage capacity; t d : discharge time; S min and S max : minimum and maximum operation speed; J: Polar inertia (PMSM + flywheel); U d : DC voltage. Motor / ψ m L d , L q R Generator Wb μH mΩ Permanent Magnet 3-phase, synchromous 82 p PMSM 0.052 100 Table 7. PMSM data ψ m : flux induced by magnet; L d and L q : d and q axis inductances; R: resistance of the stator windings. T f T t U f R on R s μs μs V mΩ kΩ 121 1100 Table 7. VSI data of the Interface and the DSTATCOM T f : Current 10 % fall time of the IGBT, T t : Current tail time of the IGBT; U f : forward voltage for IGBTs; R on : internal resistance of the IGBT device; R s : snubber resistance 9. References Ackermann, T. (2005). Wind Power in Power systems. John Wiley & Sons, Ltd, ISBN 0-470- 85508-8 (HB), England. Andrade, R.; Sotelo, G. G.; Ferreira, A. C.; Rolim, L. G. B.; da Silva Neto, J. L.; Stephan, R. M.; Suemitsu, W. I. & Nicolsky, R. (2007). Flywheel Energy Storage System Description Control of a DSTATCOM Coupled with a Flywheel Energy Storage System to Improve the Power Quality of a Wind Power System 35 and Tests, IEEE Transactions on Applied Superconductivity, Vol. 17, Nº 2, (June 2007), ISSN: 1051-8223. Barton, J. P. & Infield, D. G. (2004). Energy storage and its use with intermittent renewable energy, IEEE Transaction Energy Conversion, Vol. 19, Nº 2, pp. 441–448, (June 2004), ISSN: 0885-8969. Beacon Power website, www.beaconpower.com/, May 2009. Bose, B. K. (2002). Modern Power Electronics and AC Drives, Prentice Hall - 2002, ISBN 0-13- 016743-6, United States of America. Boutot, T.; Chang, L. & Luke, D. (2002). A Low Speed Flywheel System for Wind Energy Conversion, Proceedings of the 2002 IEEE Canadian Conference on Electrical & Computer Engineering, 0-7803-7514-9/02, Winnipeg, May 2002, Canada. Brad, R. & McDowall, J. (2005). Commercial Successes in Power Storage. IEEE power & energy magazine, Vol. 3, No. 2, (March/April 2005) pp. 24-30, ISSN 1540-7977. Cárdenas, R.; Peña, R.; Asher, G. M.; Clare, J. & Blasco-Giménez, R. (2004). Control Strategies for Power Smoothing Using a Flywheel Driven by a Sensorless Vector- Controlled Induction Machine Operating in a Wide Speed Range, IEEE Transactions on Industrial Electronics, Vol. 51, No. 3, (June 2004) 603-614, ISSN: 0278-0046. Carrasco, J. M. (2006). Power Electronic System for Grid Integration of Renewable Energy Source: A Survey, IEEE Transaction on Industrial Electronics, Vol. 53, No. 4, pp 1002- 1014, (August 2006), ISSN : 0278-0046. Cimuca, G.; Radulescu, M.M.; Saudemont, C. & Robyns, B. (2004). Comparative Study of Flywheel Energy Storage Systems Associated to Wind Generators, Proceedings of the International Conference on Applied and Theoretical Electricity - ICATE 2004, Oct 2004, Romania. Chen, Z. & Spooner, E. (2001). Grid Power Quality with Variable Speed Wind Turbines. IEEE Transactions on Energy Conversion, vol. 16, Nº 2, pp 148-154, June 2001. Ecotècnia website, www.ecotecnia.com, March 2009. Flywheel Energy Systems website, www.magma.ca/~fesi, May 2009. Han, S.; Jahns, T.M. & Zhu, Z. Q. (2008). Analysis of Rotor Core Eddy-Current Losses in Interior Permanent Magnet Synchronous Machines, IEEE, Industry Applications Society Annual Meeting, IAS '08, October 2008. Hebner, R. ; Beno, J. & Walls, A. (2002). Flywheel batteries come around again, IEEE Spectrum, Vol. 39, No. 4, pp. 46–51, (April 2002), ISSN: 0018-9235. Mohod, S.W. & Aware, M.V. (2008). Power Quality Issues & It’s Mitigation Technique in Wind Energy Generation. IEEE Harmonics and Quality of Power, September 2008. Molina M. G. & Mercado, P. E. (2004). Multilevel control of a Static Synchronous Compensator combined with a SMES coil for applications on Primary Frequency Control, Proc. CBA 2004, Gramado, Brasil, Septiembre 2004. Neg Micon website, www.neg-micon.com, March 2009. Samineni, S.; Johnson, B. K.; Hess, H. L. & Law, J. D. (2006). Modeling and Analysis of a Flywheel Energy Storage System for Voltage Sag Correction, IEEE Transactions on Industry Applications, Vol. 42, No 1, (Janaury/February 2006), 1813-1818, ISSN: 0093- 9994. Slootweg, J.G. & Kling, W.L. (2003). Is the Answer Blowing in the Wind? IEEE Power & Energy magazine, pp 26-33, November/December 2003. Energy Storage 36 Smith, J.C.; Milligan, M.R. & DeMeo, E.A. (2007). Utility Wind Integration and Operating Impact State of the Art. IEEE Transaction on Power System, vol. 32, Nº.3, pp.900-907, August 2007. Song, Y. H. & Johns, A. T. (1999). Flexible AC Transmission Systems (FACTS), IEE Press, ISBN 0-85296-771-3. London, UK. Suvire, G. O. & Mercado, P. E. (2007). Utilización de Almacenadores de Energía para Mitigar los Problemas Introducidos por la Generación Eólica en el Sistema Eléctrico, Décimo Segundo Encuentro Regional Ibero-americano del CIGRÉ, Foz do Iguazú-Pr, Brasil, Mayo 2007. Suvire, G. O. & Mercado P. E. (2008). Wind Farm: Dynamic Model and Impact on a Weak Power System, IEEE PES T&D LATINAMERICA, pp. 1-8, ISBN: 978-1-4244-2217-3, Bogotá-Colombia, August 2008. Takahashi, R.; Wu, L.; Murata, T., & Tamura, J. (2005) An Application of Flywheel Energy Storage System for Wind Energy Conversion, International Conference on Power Electronics and Drives Systems, Vol. 2, pp 932-937, 2005. Toliyat, H.; Talebi, S.; McMullen, P.; Huynh C. & Filatov A. (2005). Advanced High-Speed Flywheel Energy Storage Systems for Pulsed Power Applications, IEEE Electric Ship Technologies Symposium, 2005. Urenco Power Technologies website, http://uptenergy.com, May 2009. Xie, H.; Mei, S. & Lu, Q. (2002). Design of a Multi-Level Controller for FACTS Devices, Proc. Power Systems and Communication Infrastructures for the Future, Pekín, China, September 2002. 3 The High-speed Flywheel Energy Storage System Stanisław Piróg, Marcin Baszyński and Tomasz Siostrzonek University of Science and Technology Poland 1. Introduction At the present level of technology the electricity generation has already ceased to be a problem. However, years are passing by under the slogan of seeking for methods of effective energy storage. The energy storage method shall be feasible and environmentally safe. That's why the methods, once regarded as inefficient, are recently taken into consideration. The development in materials technology (carbon fibre, semiconductors, etc.) brought back the concept of a flywheel. This idea has been applied to high-speed flywheel energy storage. 2. Electromechanical energy storage using a flywheel A flywheel energy storage system converts electrical energy supplied from DC or three- phase AC power source into kinetic energy of a spinning mass or converts kinetic energy of a spinning mass into electrical energy. The moment of inertia of a hollow cylinder with outer radius r z , and inner radius r w is: () 44 1 2 zw Jhrr πρ =− (1) Maximum amount of kinetic energy stored in a rotating mass: () 2442 max max max 1 24 kzw WJhrr π ωρω == − (2) where: J – moment of inertia, ω – angular velocity. The force acting on a segment of spinning hoop (Fig. 1) is: 2 r v dF dm h d dr v r ρϕ = ⋅=⋅⋅⋅⋅ (3) where: ρ – density of the hoop material, h – height, r – radius, v – peripheral velocity, ϕ – angle, F – force, m – mass. The net force acting in the direction of axis x, resulting from elementary forces dF r , is: Energy Storage 38 ϕ d ϕ r dr x dF r v dF x dF y y Fig. 1. Forces acting on the segment of a rotating hoop 22 2 00 2 cos 2 cos 2 xr F dF d h dr v d h dr v ππ ϕϕ ρ ϕϕ ρ = ⋅=⋅⋅⋅ ⋅=⋅⋅⋅ ∫∫ (4) Bursting stress (in the hoop cross sections shaded in Fig. 1): 2 2 2 22 x r F hdrv v hdr hdr ρ σρ ⋅⋅ ⋅ = ==⋅ ⋅⋅ ⋅⋅ (5) Hence, the maximum allowable peripheral velocity for a material with the density ρ and allowable tensile stress maxer R σ = : 2 max e R v ρ = (6) Maximum rotational velocity of a flywheel depends on the allowable peripheral velocity at its surface (6): 2 2 max max 22 e zz vR rr ω ρ == (7) Substituting (7) into (2) we have: () () ( ) 22 2 44 22 max 22 1 4 zwe ew kzwzw z zz rrR Rr W hrr rrh V r rr π ρπ ρρ ⎛⎞ + ⎛⎞ ⎜⎟ =−=− =+ ⎜⎟ ⎜⎟ ⎜⎟ ⎝⎠ ⎝⎠ (8) Hence can be found the flywheel mass: () 22 max 2 4 1 1 k zw e w z W mhrr R r r π ρρ =−= ⋅ ⎛⎞ + ⎜⎟ ⎝⎠ (9) The High-speed Flywheel Energy Storage System 39 In order to minimize the flywheel mass it shall be made in the form of a thin-walled hollow cylinder. From relation (9) the ratio of maximum stored energy to the flywheel mass is: 2 max max 1 4 w z kke r r WWR mV ρρ ⎛⎞ + ⎜⎟ ⎝⎠ ==⋅ (10) For zw rr≈ relation (10) reduces to the form of: 2 max max 22 ke WRv m ρ ≈= (11) As follows from (11), a light structure (a large amount of energy per unit of mass) can be achieved using a material with possible low density ρ and high tensile strength R e . Materials that meet these requirements are composites (Kevlar, carbon fibre, glass fibre in combination with a filler) or composite bandage (in order to improve stiffness) on a ring of a light metal, e.g. aluminium. Density ρ [kg/m 3 ] Strength Re [GPa] v max [m/s] W/m [MJ/kg] Steel 7.8⋅10 3 1.8 480.4 0.23 Titanium 4.5⋅10 3 1.2 516 0.27 Composite glass fibre 2.0⋅10 3 1.6 894.4 0.80 Composite carbon fibre 1.5⋅10 3 2.4 1256 1.60 Table 1. Parameters of typical flywheel materials A flywheel of a larger energy per unit of mass and the given outer radius r z , chosen for constructional reasons, has to rotate with a higher peripheral velocity (11) and, consequently, with a higher angular velocity (7). Since in this case peripheral velocities of high-speed rotors are exceeding the speed of sound, the rotor should be enclosed in a hermetic vacuum chamber. In consequence, the energy store structure - and particularly bearings, become complicated (due to vacuum maintained in inside the enclosure should be used magnetic bearings and a system stabilizing the rotor axle position in space The flywheel, integrated with the electric machine, should rotate without a contact with motionless parts (magnetic levitation). Magnetic bearings should be made of permanent magnets (high efficiency is required) while an electromagnetic system should only assist them to a certain extent and stabilize the axle position. Due to a required very high efficiency, the flywheel shall be driven by a permanent magnet motor installed inside the enclosure. Vacuum inside the enclosure prevents exchange of heat between the FES components and causes problems with heat removal from windings of the electric machine operated as a motor or generator. An advantage of vacuum is lack of losses caused by the rotor friction in air (at peripheral velocities of 700-1000m/s) and noiseless operation. [...]... quick charging and discharging) 4 Electric machine for the flywheel energy storage purposes Flywheel energy storage systems can utilize all types of AC three-phase machines The choice of the machine type is determine by the energy storage application and particularly by expected duration of energy storage In energy storage systems with expected long duration of energy storage idle losses should be radically... Examples of flywheel energy storage applications In an autonomous system with alternative electric energy source (Fig 2a) the energy store supplies loads if loss of supply from a base power source occurs The energy storage can be used in uninterruptible power supply systems (UPSs) of selected loads (Fig 2b) Upon voltage loss or decrease in the line voltage magnitude a load and energy storage system are... for particularly important and sensitive processes • Systems for storage and controlled release of energy produced by alternative autonomous electric power sources, like photovoltaic or wind power plants In such systems store energy in time when there is no demand from electricity users A flywheel energy storage system intended for supporting alternative autonomous sources shall exhibit very high energy. .. DC/AC BLDCM Flywheel Fig 2 Examples of spinning energy storage applications; AC/DC, DC/AC – power electronic converters, BLDCPM – electric machine (Brushless D.C Permanent Magnet Motor) 6 Controlling energy release from a flywheel energy storage system The amount of energy stored in a rotating mass is proportional to the angular velocity squared It means that energy store can be effectively utilized within... duration of energy storage should be radically limited Such systems can utilize asynchronous induction machines or synchronous machines During energy charging or discharging a small amount of energy is needed for the machine excitation (power losses in the field winding resistance in a synchronous machine or losses due to the magnetizing (reactive) component in an induction machine) In energy storage systems... powers, etc.), smaller peak contracted power Urban buses Flywheel energy storage systems designed for mobile applications with • relatively small energy stored (6÷10 MJ) and suitable for charging and discharging with large powers (100÷150 kW) can be utilized in urban buses (charged at bus stops) The High-speed Flywheel Energy Storage System • 41 Urban and suburban electric transportation systems and hybrid... thyristor switches) from the supply line and energy store turns to the generator mode, thereby powering sensitive (critical) loads Another application of an energy storage system is stabilization of supply voltage (or limitation of peak currents in a supply line) of loads characterized with fast-changing, shortduration loading far exceeding the average load 42 Energy Storage (a) Support of alternative autonomous.. .40 Energy Storage The electric machine must be controlled by a power electronic system enabling its operation as a motor or generator and adjusting electric power parameters alternately to the needs of the accelerated spinning mass or electrical loads (or an electric network) supplied from FES If the energy storage system is operated as an autonomous energy source (isolated... and suburban electric transportation systems and hybrid vehicles (internal combustion engine, generator, electric motor), flywheel energy storage systems can absorb kinetic energy of a braking vehicle and reuse it during travel 3 Technical requirements for flywheel energy storage systems • • • • • High efficiency Small mass and volume Reliability, durability and safety Capability for operation in a three-phase... discharging large electromagnets Elevators in buildings with intensive traffic flow ("intelligent building") An elevator • equipped with an energy storage system will consume energy solely to compensate losses • Large industrial plants (large-power flywheel energy storage systems) in order to mitigate voltage fluctuations, power supply back-up during supply systems switching, and power quality improvement . & Infield, D. G. (20 04) . Energy storage and its use with intermittent renewable energy, IEEE Transaction Energy Conversion, Vol. 19, Nº 2, pp. 44 1 44 8, (June 20 04) , ISSN: 0885-8969. Beacon. is determine by the energy storage application and particularly by expected duration of energy storage. In energy storage systems with expected long duration of energy storage idle losses should. been applied to high-speed flywheel energy storage. 2. Electromechanical energy storage using a flywheel A flywheel energy storage system converts electrical energy supplied from DC or three- phase