Load Frequency Control in Three Area Network with Intelligent Controllers

Transcription

1 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 Load Frequency Control in Three Area Network with Intelligent Controllers J. rinu Naick *, K.Chandra ekhar * Associate professor, Department of Electrical & Electronics Engineering, PNV&VIET, Repudi (V), Phirangipuram(M),Guntur (Dt); A.P, India, srinunaik.eee@gmail.com, Professor & HOD Department Of Electrical &Electronics Engineering,R.V.R & J.C.College of Engineering, Chowdavaram, Guntur, A.P, India, cskoritala@gmail.com Keywords: Automatic Generation Control (AGC), proportional integral (PI), Tieline, Frequency deviation, Control. Abstract This paper presents decentralized control scheme for Load Frequency Control in a multiarea Power ystem by appreciating the performance of the methods in a single area power system. A number of modern control techniques are adopted to implement a reliable stabilizing controller. A serious attempt has been undertaken aiming at investigating the load frequency control problem in a power system consisting of three power generation unit and load units. The robustness and reliability of the various control schemes is examined through simulations. In this paper, change in frequency was observed for the system without control; with PI viz. Proportional Integral controller approach of automatic generation control along with fuzzy controller has been examined. PI and fuzzy based AGC have been used for all optimization purposes. The response of frequency change in individual area due PI and fuzzy based AGC controllers have been compared with the system without control in this paper. The 3area frequency deviation was tabulated comparing PI controller, fuzzy controller and the system without control effectiveness. Introduction Automatic Generation Control (AGC) is associate integral a part of Energy Management ystem. This paper deals with the automatic generation control of interconnected multi area grid network. The first purpose of the AGC is to balance the full system generation against system load and losses so the specified frequency and power interchange with neighbouring systems are maintained. Any pair between generation and demand causes the system frequency to deviate from regular worth. o high frequency deviation could result in system collapse. This necessitates associate correct and quick acting controller to take care of constant nominal frequency. The limitations of the conventional controls are slow and lack of efficiency in handling system nonlinearity. This leads to develop a control technique for AGC. The ultimate objective of automatic generation control (AGC) is to maintain the balance between power output of the electrical generator and load demand so as to keep the frequency within the acceptable limits, in response to the changes in the system and tieline loading. This function is normally termed as load frequency control (LFC) []. The power systems are widely interconnected for its reliability all over the globe. Interconnection not only enhances system reliability but also improves the system efficiency. ince the system is wide and complex, for the faithful operation, the analysis of the system is of greater importance. Currently system became too complex with addition of more utilities, which may leads to a condition where supply and demand has got a wide gap [2]. Due to heavy load condition in tielines by electric power exchange results in poor damping which may leads to interarea oscillation. ince the loading conditions are unpredictable, this makes the operation more complex. It has been a topic of concern, right from the beginning of interconnected power system operation. In this context, Automatic Generation Control plays a vital role in the power system operation. everal works have been carried out for the AGC of interconnected power systems for last few decades [3][7]. Automatic Generation Control (AGC) allows dispatchers to change the relative phase angle between two system voltages, thereby helping them to control real power transfers between the two interconnected power systems. It attenuates the frequency of oscillations of power flow following a load disturbance in either of the areas, as well. Phase shifters also provide series compensation to augment stability. The highspeed responses of phase shifters make them attractive for use in improving stability. The AGC is expected to be an effective control for the tieline power flow control of an interconnected power system. Usually sudden changes in power requirement are met by kinetic energy of generator rotor, which effectively damp electromechanical oscillations in power system [2]. 2 Proposed ALFC for frequency control Valve/Gate Turbine Governor T Tm Te (peed) Generator G Power Network Fig.. The chematic representation of ALFC system 529

2 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 Fig.. shows the schematic diagram for automatic load frequency control (ALFC). In this structure turbine is fed by steam or water input. The input of the turbine can be controlled by valve. A turbine is a rotating mechanical device that extracts energy from a fluid flow and converts it into mechanical energy. A turbine is a turbo machine with at least one rotating part called a rotor, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. This turbine may be a water turbine, steam turbine, gas turbine or wind turbine. The turbine shaft is mechanically coupling to the alternator. The alternator converts mechanical energy into electrical energy. This electrical energy can be given to grid through an interfacing transformer. i. ingle Area Control i. ThreeArea ystem without ALFC G2 G22 G23 Bus Area 2 G G2 G3 Bus Area Gn LOAD Bus Area 3 G3 G32 G33 Pref() Pref() Kg stg stt Pg() Governor Pv() peed Droop R K Turbine Po() 2Hs Kt D Pm() Primary Loop upplementary Loop Power ystem Fig.2.The block diagram representation of single area AGC Fig.2. shows the block diagram of automatic generation control in single area. This block diagram has two loops i.e. primary loop and supplementary loop. Primary loop achieves the real power balance by adjusting the output of the turbine for matching of change in load demand. All other generating units balance the change in load variations. But this results a supply frequency variations. These frequency deviations can be controlled by another control loop, which is called supplementary loop. In this loop integral controller is used to makes frequency deviation is zero. 3 Interconnected power system The power systems are widely interconnected for its reliability all over the globe. Interconnection not only enhances system reliability but also improves the system efficiency. ince the system is wide and complex, for the faithful operation, the analysis of the system is of greater importance. ( ) G2n TieLine 23 LOAD 2 LOAD 3 Fig. 3. Threearea power generation system Currently system became too complex with addition of more utilities, which may leads to a condition where supply and demand has got a wide gap [2]. Due to heavy load condition in tielines by electric power exchange results in poor damping which may leads to interarea oscillation. ince the loading conditions are unpredictable, this makes the operation more complex. It has been a topic of concern, right from the beginning of interconnected power system operation. The block diagram of interconnected generating system is shown in fig.3.these three generating areas are interconnected by tie lines. In this each area has one ALFC loop, they are combined and shown in fig.4. ii ThreeArea with ALFC A Threearea interconnection is comprised of regions, or areas, that are interconnected by tielines. Tielines have the benefit of providing interarea support for abnormal conditions as well as transmission paths for contractual energy exchanges between the areas. The area boundaries are determined by tieline metering for AGC and contractual billing purposes [3]. In an interconnection where AGC in more than one area is driven solely by a frequency signal, there will be large power oscillations between controlling areas unless regulating actions taken by all areas can be realized simultaneously. Further, the operation of such an interconnection would face a more severe problem if the areas attempting to control frequency had measurement error. An area that measured the frequency at a value higher than others would reduce its generation, while others raised, both attempting to force frequency (as they each measured it to the scheduled value. G3n 530

3 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 A C E K B R 2 G o v e r n o r T u r b in e P m ( ) P L ( ) 2 H D P m 2( ) P 2 Pg A C E 2 K 2 G o v e r n o r 2 T u r b in e 2 ACE 3 B 2 K3 Governor 3 R Turbine 3 R 3 P23 PL 3 P L 2() 2 H 2 D 2 Pg 2H3 D B3 Fig.4. AGC for threearea operation. 4. Matlab/imulink results Case i: Frequency variations without Controller Fig. 6: imulink result of frequency variation of area without PI controller Fig. 7: imulink result of frequency variation of area2 without PI controller Fig.5 imulink model of 3LFC without Controller Fig. 8: imulink result of frequency variation of area3 without PI controller 53

4 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 Figure 5 shows the imulink model of frequency variation in 3area load frequency control without PI controller. Figure 6 shows the frequency variation in area and frequency variations in area2 and area3 are shown in figure 7 and figure 8 respectively. Fig. 2: Frequency variation of area with PI controller Fig. 9: imulink result of frequency variation of tieline between area and area2 without PI controller Fig. 3: Frequency variation of area2 with PI controller Fig. 0: imulink result of frequency variation of tieline between area3 and area2 without PI controller Figure 9 shows the frequency variation in tieline connecting area and area2 without PI controller. The frequency response of tieline connecting area2 and area3 without PI controller is shown in figure 0. Case ii: Frequency variations with PI Controller Fig. 4: Frequency variation of area3 with PI controller Figure shows the imulink model of frequency variation in 3area load frequency control with PI controller. Figure 2 shows the frequency variation in area and frequency variations in area2 and area3 are shown in figure 3 and figure 4 respectively with PI controller. Fig. 5: Frequency variation of tieline between area and area2 with PI controller Fig. imulink model of 3LFC with PI Controller Fig. 6: Frequency variation of tieline between area3 and area2 with PI controller 532

5 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 Figure 5 shows the frequency variation in tieline connecting area and area2 with PI controller. The frequency response of tieline connecting area2 and area3 with PI controller is shown in figure 6. Case iii: Frequency variations with Fuzzy Controller Fig. 7: Frequency variation of area with Fuzzy controller AGC CONTROLLER WITHOUT PI WITH PI WITH FUZZY AREA AREA AREA TIE LINE Connecting area and area2 TIE LINE Connecting area and area Table load variation Table I shows the variation in the network with and without PI controller and with Fuzzy controller. The table clearly indicates that without PI controller, the frequency oscillations are more in number and it takes much time to settle down without controller. With fuzzy controller, the settling time still reduces giving more stability to the system. Fig. 8: Frequency variation of area with Fuzzy controller Fig. 9: Frequency variation of area with Fuzzy controller Figure 7 shows the frequency variation in area and frequency variations in area2 and area3 are shown in figure 8 and figure 9 respectively with Fuzzy controller. Fig. 20: Frequency variation of tieline between area and area2 with Fuzzy controller Fig. 2: Frequency variation of tieline between area3 and area2 with Fuzzy controller Figure 20 shows the frequency variation in tieline connecting area and area2 with Fuzzy controller. The frequency response of tieline connecting area2 and area3 with Fuzzy controller is shown in figure 2. 5 Conclusion Change in system frequency is one of the most serious issues in power system as it can cause serious threat to the complete system stability. Load changes are very much common in the power system and this change in load causes the frequency to swing. Control measures have to be taken to control the swing of frequency of the system. Without controller, the change in frequency persists for longer time. Conventional PI controller can be adopted to control the swing but still the swing is found to be sustained for longer time period. Fuzzy controller to control the change in frequency effectively damps the oscillations in system frequency. The comparative analysis of the settling time of frequency in the system without controller, with PI control and Fuzzy controller was explained along with the results. Frequency variations in individual load frequency areas were shown along with their tieline frequency result of threearea system. References []. M.R.I. heikh, R. Takahashi, and J. Tamura MultiArea Frequency and TieLine Power Flow Control by Coordinated AGC with TCP IEEE 6th International Conference on Electrical and Computer Engineering. [2]. Feliachi, A., On Load Frequency Control in a Deregulated Environment, IEEE Inter. Conference on Control Applications, pp , 58 ept [3]. J. Nanda, A. Mangla and. uri, ome New Findings on Automatic Conventional Controllers, IEEE Transactions on Energy Conversion, Vol. 2, No., pp. 8794, March,

6 3 rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and ciences (EEECO)206 [4]. A.Demiroren, Application of a elftuning to Automatic Generation Control in Power ystem Including ME Units, ETEP, Vol. 2, No. 2, pp. 009, March/April [5]. Jiang, H.; Cai, H.; Dorsey, F.; QU, Z., Toward a Globally Robust Decentralized Control for Large cale Power ystems, IEEE Trans. on Control ystem Technology 5 No.3, (997), [6]. Bengiamin, N. N.; Chan, W. C., Variable tructure Control of Electric Power Generation, IEEE Trans. on PA, 0 (982), [7]. AlHamouz, Z. M.; AlDuwaish, H. N., A New Load Frequency Variable tructure Controller Using Genetic Algorithms, Electric Power ystems Research 55 No. (2000), 6. [8]. R.N. Patel, Application of Artificial Intelligence for Tuning the Parameters of an AGC, International Journal of Mathematical, Physical and Engineering ciences, Vol., No., pp. 3440, May [9]. Zeynelgil, H. L.; Demiroren, A.; engor, N.., The Application of ANN Technique to Automatic Generation Control for MultiArea Power ystem, Electrical Power and Energy ystems, 24 (2002), Biographies: J. rinu Naick received his B.E degree in Electrical & Electronics Engineering from Andhra university Vishakhapatnam AP, India in 2003 and M.Tech with Energetics from NIT Calicut, Calicut, Kerala, India in He is having 3 years of teaching and research experience. He is currently Associate Professor & Head in the Department of Electrical & Electronics Engineering, PNC&VIET, Repudi, Phringipuram, Guntur, AP, India. His Research interests are in the areas of Power systems Industrial Drives & FACT Controllers. K. Chandra ekhar received his B.Tech degree in Electrical & Electronics Engineering from V.R.iddartha Engineering College, Vijayawada, India in 99 and M.Tech with Electrical Machines & Industrial Drives from Regional Engineering College, Warangal, India in 994. He Received the PhD, degree from the J.N.T.U, Hyderabad, India in He is having 7 years of teaching and research experience. He is currently Professor& Head in the Department of Electrical & Electronics Engineering, R.V.R & J.C. College of Engineering Guntur, India. His Research interests are in the areas of Power Electronics, Industrial Drives & FACT Controllers. 534