ISSN Vol.04,Issue.20, December-2016, Pages:

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1 ISSN Vol.04,Issue.20, December-2016, Pages: Frequency Stability Analysis of Hybrid Power System based on Solar PV Integration of Secondary Storage System with SMEs Unit NELLI CHANDRA SEKHAR 1, SH SURESH KUMAR BUDI 2 1 PG Scholar, Dept o f Power Systems, Gokul Group of Institutions, AP, India. 2 Assistant Professor, Dept of Power Electronics, Gokul Institute of Technology and Sciences, JNTUA, AP, India. Abstract: Storage Technology has emerged as main backup powers provider in the era of Smart Grid. Frequency stability analysis of a hybrid power system (HPS) based on solar PV and Superconducting Magnetic Energy Storage system (SMES) unit have discussed. Generally, frequency instability problem occurs due to abrupt variation in load demand growth and generated power variations from different renewable power sources. To Solve these fluctuating problem, renewable power generators are equipped with various storage system. On the bases of frequency stability, effect of enabling the SMEs operation with the HPS has also been analyzed. HPS model has simulated in two different cases. First one is the steady state analysis with controller and another is dynamic operation of the system throughout a day. In the presence of large disturbance, the effect of limited storage capability of SMES unit as large disturbance is also being considered. MATLAB/Simulink platform is used for analyzing the HPS model. From Simulation results it is observed that SMES unit can mitigate the frequency fluctuations and improves system stability in both cases for variable PV power and uneven demand loads. Deployment of another battery source for storage purpose: However, deployment of SMES is not simple to store such large power. From point of economic operation this technology is lacking due to high cost of SMES.so the implementation will be difficult so by incorporating another supporting battery we could achieve the implementation of SMES at a lower cost and efficiently. Keywords: Renewable Power, Photovoltaic, Energy Storage, SMES, Micro-grid, Frequency stability, Hybrid Power System. I. INTRODUCTION Looking into the effect of greenhouse on earth's atmosphere we can very well understand the importance of renewable energy generation which is totally pollution free. These sources include wind energy, solar energy, tidal energy wave energy, ocean energy, geothermal energy, and biomass& bio gas energy [1], [14]. Renewable energy technologies are clean sources of energy that have a much lower environmental impact than conventional energy technologies. Among all renewable, PV systems are getting more attraction worldwide [14-16].Major application of the PV system to provide power facilities to satellite equipment s, off grid application where the grid integration is not possible or not available grid connected application [2],[21]. PV arrays can be installed in domestic locations such facades, rooftops of buildings, and shades of parking lots. Power coming from this type of plants can be injected to local grid or may be used to compensate domestic load demand. There are many projects going on worldwide based on solar power facilities with storage [1-4]. Even though applications of PV system, increasing drastically, but this technology still facing many hurdles such as the intermittent nature of environmental concerns, their high capital cost, and variable output power creates instability in the grid connected system [2], [16]. Another main concern that appearances the globally installation of grid-connected PV systems, operational problems in distribution system, especially when a large megawatt PV system is connected into the electric grid. This is the area where researchers are about to think. The effect of installed PV systems on the performance of the micro-grid PV system with storage system has analyzed. To solve these issues, various storage devices are incorporated with renewable power system. In comparison to other storage system such as BESS, Hydro pump and, others that they are having problems like limited lifecycle, low response time, storage capacity, voltage and current limitation, large unit size and environmental hazards etc. SMES unit have not such issues. [5-9],[19]. Due to salient features like rapid response, injecting/ absorbing real or reactive power ability, inherently huge storage efficiency various authors have their proposed work on integration of SMES in Electrical Power system. Ref. [9], [10] have discussed about impact of SMES in grid connected power system for transient disturbance conditions. Improvement of system frequency by SMES with different controllers in presence wind and diesel power sources has presented in ref. [11], [13], and [18]. Power flow control and management through energy storage have been discussed in ref. [12], [14]. Various authors have prepared their methodology to minimization of frequency fluctuation within citing SMES in their hybrid system [15-17]. Different load frequency controlling techniques such as PID and Artificial Neural Network is presented in [21], [23]. Due to integration of storages and renewable sources power quality issues like harmonics also a serious problem discussed in [2425]. This 2016 IJIT. All rights reserved.

2 paper is extension version of our previous work discussed in [20]. Step load response analysis and controller was not included in ref. [20]. system, has been analyzed in steady and dynamic state with optimized PI controller in both cases. Performance of micro-grid integrated hybrid solar system with and without SMES has been analyzed by considering variable load demand. The impact of SMES of operation of hybrid solar system has carried out. The frequency stability analysis of HPS under the micro grid connected situation with SMES unit have presented. Limit on SMES inductor coil current also incorporated in this work. NELLI CHANDRA SEKHAR, SH SURESH KUMAR BUDI C. Modelling of SMES Unit Figure 2 shows the configuration unit of SMES. It consists mainly three parts name as superconducting coil which is the heart of the system, PCS and control unit. Control unit of the SMES unit has shown in fig.3. Detailed modelling of SMES have well documented in [14], [20]. Charging/discharging of the SMES unit is controlled by changing the value of commutation angle α. When α < 90 converter is in charging mode & in inverter mode α > 90 [11] [12]. Power is feed to micro grid when frequency goes down. Thyristors cannot change the direction of inductor current suddenly so control voltage having with negative nature. Fig.1. Block Diagram of HPS with SMES II. DESCRIPTION AND MODELING OFHPS Schematic diagrams of Hybrid Power System (HPS) have shown in Fig. 1. HPS consists mainly three components as Power Generation Sources as solar PV, DEG. SMES as a Storage System. Power Conditioning System (PCS) and load Demand. Power sources and storage facility have connected to the micro-grid. SMES is operating in to & from mode ie it consumes from micro grid and delivered power to the micro grid. Modelling of power sources and storage system has been done. Study of PCS system has not been presented. An assumption has been considered that all required PCS system working properly in the system. This system model is also useful for Distributed and isolated system. A. Modelling of Solar PV System Complete Solar PV system is the arrangement of many PV arrays and other ancillary services. Group of solar cells is called as PV arrays. Ideal solar cell is defined as [3], [1] B. Diesel Engine Generator Model. Fig.3. Block Diagram of HPS with SMES D. Controlling Technique The actuating signal for PI controller is the summation of proportional and integral of the error signal. Gain of PI controller is shown as [21] (1) (1) Where Kp, KI are Proportional& Integral gain respectively. The optimized value of Kp& KI is calculated through genetic algorithm optimization tool. E. Mathematical Modelling of HPS Mathematical model of HPS has been discussed in this section. Fig. 4 shows the transfer function based model of HPS. Assumed that PCS is properly working at their defined positions. Table I shows the parameters of HPS used in modeling. In order to sustain stability of the grid connected system, load generation balance must be maintained with proper power flow control. The controlling error from variation between load demand ( PD) and change in net power production ( PT) decides the control strategy. Fig.2. Schematic Diagram of the SMES Unit Fig.4.

3 Frequency Stability Analysis of Hybrid Power System based on Solar PV Integration of Secondary Storage System with SMEs Unit III. SYSTEM ANALYTICS during peak load demand in static mode has shown in System analytics of the micro grid HPS have shown in figure 6(a) & (b) respectively. C. Case II 1) figure 5. The grid frequency varies with the variation of the load demand so whenever rise or fall occurs in load demand grid frequency also changed. Effect of variation of frequency and load demand on grid is inversely proportion to each other. For stable operation of HPS, grid frequency must lie within acceptable range. Control of power supply has to regulate with respect to load fluctuation to neutralize the frequency fluctuations. When grid frequency goes to below 50 Hz or Fig.6(a) Frequency Response during peak load Demand in negative in nature then SMES is feeding the power into the static Mode grid. However SMES unit have to check limits of the superconducting coil current (Id) with its lower limit of inductor current (IdL). SMES feeds the power to the grid & gets discharged when If Id >IdL otherwise it is in off mode. In another case when grid frequency goes to above 50 Hz or positive in nature than SMES does not feed the power. Few part of the surplus power is consumed by SMES in charging mode. Firstly SMES unit checks it s charging inductor current limits with IdU while operating in charging mode. When there is no variation in grid frequency, SMES remains in standby mode. Fig.6(b) SMES Response During Peak Load Demand in static Mode Fig.7(a). Frequency Response during peak load Demand in Static Mode Fig 5. Flow of the system analytics IV. SIMULATION RESULTS ANDANALYSIS This section presents the simulation results of HPS models. Analysis of HPS is done in two modes static/steady state and dynamic modes. In static mode step load change has been consider for analysis of HPS stability. But in dynamic mode variation of load of a1 typical day have been considered for stability analysis. A. Mode A Steady state or Static mode Stability Analysis of HPS Model In static mode frequency stability analysis of HPS have analyzed with step load change during peak load & off-peak load demand. B. Case I 1) During peak load Sudden increase in 500 KW step load change have been considered for this case. Frequency will drop due to sudden rise in load demand. SMES start supplying the power to grid to maintain grid frequency constant. Now SMES is operating in discharging mode. Frequency and SMES response Fig.7(b) SMES Response during off Peak Load Demand in Static Mode A. Phase B Real time or dynamic simulations for 24 hours In phase B, HPS model has been simulated for a typical day with dynamic mode. Study of dynamic mode operation has been carried out in two cases with increase & decrease in load demand hours. Variations of temperature, solar irradiation and power generated have shown in figure 8,9,10 respectively. Load profile throughout a typical day has shown in figure 11.

4 B. Case I 1. Increase in Load Demand Grid frequency lowered with increase in load demand. To balance the load generation ratio, DEG start power feeding to grid up to its maximum capacity. If system frequency is not coming its specified range than SMES delivering the power to grid to compensate the load demand C. Case II Decrease in load Demand With reduction load demand, grid frequency increased. In order to maintain constant frequency total generation should be decrease with shutting down DEG and change the mode of operation of SMES. Some surplus power of grid is consumed by SMES in charging mode. Total operating behavior of SMES has shown in figure 12. Variation of DEG power flow has shown in Fig. 13. Fig.8. Variation of Solar Irradiation Throughout a Day Fig.9. Variation of PV Power Fig.10. Variation of SMES / PV Power Fig.11. Variation in Frequency of the System NELLI CHANDRA SEKHAR, SH SURESH KUMAR BUDI V. CONCLUSION The effect of SMES on reduction on the frequency fluctuations of micro grid connected PV with variable PV power output has been proposed. The performance of the hybrid system is evaluated considering variable load demand and secondary storage with Optimized PI controller. From obtained results it can be conclude that frequency control with SMES are providing better response in comparison to without SMES. Storage facility is controlling deviation of grid frequency in both modes of operation. However deployment of SMES is not simple to store such large power. From point of economic operation this technology is lacking due to high cost of SMES. so the implementation will be difficult so by incorporating another supporting battery we could achieve the implementation of SMES at a lower cost and efficiently. VI. REFERENCES [1]Frequency Stability Analysis of Hybrid Power System based on Solar PV with SMEs Unit, Shailendra Singh1, Rohit Kumar Verma2,Ashish Kumar Shakya3 and Satyendra Pratap Singh4, International Conference on Emerging Trends in Electrical, Electronics and Sustainable Energy Systems, /16/$ IEEE [2]Omran, Walid. Performance Analysis of GridConnected Photovoltaic Systems. Diss. University of Waterloo, [3]Chen Qi, Zhu Ming, Photovoltaic Module Simulink Model for a Stand-alone PVSystem, Science Direct International Conference on Applied Physics and Industrial Engineering, Physics Procdia vol. 29, pp , [4]S. Chanana, and A. Kumar, Operation and control of BESS using frequency-linked pricing in real-time market with high wind penetration, International Journal of Energy Sector Management, Vol. 5, pp , [5]Singh, S.; Singh, M.; Chanana, S.; Raveendhra, D., "Operation and control of a hybrid wind-diesel-battery energy system connected to micro-grid," in Control, Automation, Robotics and Embedded Systems (CARE), 2013 International Conference on, vol., no., pp.1-6, Dec [6]Mohd. Hasan Ali, Bin Wu, and Roger A. Dougal, An Overview of SMES Applications in Power and Energy Systems, IEEE Trans. on Sustainable Energy, vol. 1, no. 1, pp April 2010 [7]Chen L.Liu, Y. Arsoy A.B., Ribeiro P.F., Steurer M., Iravani M.R., Detailed Modeling of Superconducting Magnetic Energy Storage (SMES) System, IEEE Trans. on Power Delivery, vol. 21, no. 2, pp , April [8]Tomonori Nakayama, Tsuyoshi Yagai, Makoto Tsuda, and Takataro Hamajima, Micro Power Grid System with SMES and Superconducting Cable Modules Cooled by Liquid Hydrogen, IEEE Trans. On Applied Superconductivity, vol. 19, no. 3, pp , June 2009 [9]S. Banerjee, J. K. Chatterjee, S. C. Tripathy, Application of Magnetic Energy Storage Unit as load Frequency Stabilizer, IEEE Trans. On Energy conversion, vol. 5, no. 1, March [10]S. C. Tripathy, M. Kalantar, R. Balasubramenian, Dynamic and Stability of Wind and Diesel Turbine generators with Superconducting Magnetic Energy Storage

5 Frequency Stability Analysis of Hybrid Power System based on Solar PV Integration of Secondary Storage System with SMEs Unit Unit, IEEE Trans. On Energy conversion, vol. 6, no. 4, [23]Das, Sayari, Devesh Shukla, and S. P. Singh. "Single and December two area LFC using RBF." In Recent Developments in [11]Mohd. Hasan Ali, Minwon Park, In- Keun Yu, Toshiaki Control, Automation and Power Engineering (RDCAPE), Murata, Junji tamura, Improvement of windgenerator IEEE International Conference on, vol., no., pp , Stability by Fuzzylogic-Controlled SMES, IEEE Trans. On Industry Applications, vol.45, no. 3, pp , May/June [24]AlokJain and SumanBhullar, PI and fuzzy controller based DVR to mitigate power quality and reduce the [12]Marcelo Gustavo Molina, Pedro Enrique Mercado, harmonics distortion of sensitive load, IEEE International Power Flow Stabilization and Control of Microgrid with Conference on Advanced Computing and Communication Wind Generation by Superconducting Magnetic Energy Technologies, Panipat, India,vol., no., pp , Storage, IEEE Transactions on Power Electronics, vol. 26, November 2013 no. 3, March [25]AlokJain and SumanBhullar, Effectiveness of DVR to [13]M. Mohamed Thameem Ansari, S. Velusami, Dual compensate the load voltage harmonics in distribution mode linguistic hedge fuzzy logic controller for an isolated networks under various operating conditions (using FOC winde-diesel hybrid power system with superconducting induction motor as load), International Journal of Advanced energy storage system unit, Elesvier Energy Conversion and Research, vol. 1, no. 7, pp , September Management, vol. 51, pp July [14]Jae Woong Shim; Youngho Cho; Seog-Joo Kim; Sang Won Min; Kyeon Hur, "Synergistic Control of SMES and Battery Energy Storage for Enabling Dispatchability of Renewable Energy Sources," IEEE Trans. on Applied Superconductivity, vol.23, no.3, pp , , June 2013 [15]A.-Rong Kim, Sang-Yong Kim, Kwang-Min Kim, Jin- Geun Kim, Seokho Kim, Minwon Park, In-Keun Yu, Performance Analysis of a Toroid-Type HTS SMES Adopted for Frequency Stabilization IEEE Trans. on Applied Superconductivity, vol. 21, no. 3, pp June 2011 [16]Byung-Kwan Kang; Seung-Tak Kim; Sun-Ho Bae; Jung- Wook Park, "Effect of a SMES in Power Distribution Network With PV System and PBEVs," Applied Superconductivity, IEEE Trans. on, vol. 23, no.3, pp , , June [17]Ali, Mohd.H.; Tamura, J.; Bin Wu, "SMES strategy to minimize frequency fluctuations of wind generator system," Industrial Electronics, IECON th Annual Conference of IEEE, vol., no., pp , 1013 Nov [18]Marcelo Gustavo Molina, Pedro Enrique Mercado, Power Flow Stabilization and Control of Microgrid with Wind Generation by Superconducting Magnetic Energy Storage, IEEE Trans. on Power Electronics, vol. 26, no. 3, March [19]Singh, S.; Singh, S.K.; Chanana, S.; Singh, Y.P., "Frequency regulation of an isolated hybrid power system with Battery energy storage system," Power and Energy. [20]Singh, S.; Joshi, H.; Chanana, S.; Verma, R.K., "Impact of Superconducting Magnetic Energy Storage on frequency stability of an isolated hybrid power system," Computing for Sustainable Global Development. [21]Rawat, Swati; Singh, S.; and Kshitij Gaur. "Load frequency control of a hybrid renewable power system with fuel cell system." In Power India International Conference (PIICON), th IEEE,vol., no., pp. 16., [22]S.Singh, M. singh, S. Chanana,S. Semwal, Frequency Regulation of Isolated Hybrid Wind/Diesel, Power Generation with Fuel Cell System Lecture Notes in