Concurrent Placement of Distributed Generation Resources and Capacitor Banks in Distribution Systems Milad Doostan, Shashank Navaratnan, Saeed Mohajeryami, Valentina Cecchi Energy Production and Infrastructure Center (EPIC) Electrical and Computer Engineering Department University of North Carolina at Charlotte Charlotte, NC, USA Email: {mdoostan, snavarat, smohajer, vcecchi}@uncc.edu Abstract—In this paper, a new approach for placement of both Distributed Generation (DG) units and capacitor banks in distribution systems is proposed. The goal is to 1) reduce the total real and reactive power losses, 2) improve the voltage profile, and 3) improve the power factor for the total demand. The method uses a bus-ranking scheme based on a weighted sum of indices representative of the impacts that a DG unit or capacitor bank would have in terms of the three aforementioned objectives. Moreover, the introduced indices provide a quantitative measure to identify whether placing a DG unit or a capacitor bank is more beneficial at each bus. In order to assess the performance of the proposed method, a 49-bus distribution system is introduced. The method is applied on the test system and best locations for allocation of DG units and capacitor banks on each branch are identified. Besides, a comparison between the performance of DG units and capacitor banks at each bus is noted. At the end, by examining the resulting real and reactive power losses, voltage profile and power factor, it is demonstrated that the proposed method successfully accomplishes its objectives. Index Terms—DG placement; capacitor placement; loss reduction; voltage profile improvement; power factor improvement I. I NTRODUCTION In recent decades, the traditional energy resources have increasingly become identified with serious environmental problems. In addition, the growing electricity demand is presenting challenges to the operation of the conventional power system [1]. Consequently, the electricity industry is seeking for alternative solutions to address the aforementioned environmental and operational issues. One effective answer is the integration of DG units into the power system [2]. DG units are commonly known as the electric power generation technologies that could be integrated within the distribution systems [3], [4]. DG units offer various advantages over the traditional power generation. The operational advantages include loss reduction, congestion alleviation, interruption and transients alleviation, reactive power support, voltage profile improvement, resiliency improvement, providing electricity for remote areas, improving efficiency, and etc [3] , [5]–[10]. Furthermore, DG units, by employing the renewable resources, could offer better environmental protection. On the other hand, should the wrong settings be selected for the DG units, sundry challenges would be posed to the safe and reliable operation of the power systems. For instance, as DG technologies, specifically renewable resources, mainly depend on the weather conditions or the owner’s decision in order to generate electricity, the concerns of reliability and maintaining adequate generation reserve’s margins might come to the fore [3], [11], [12]. Also, another important issue, caused due to the high penetration of DG units, is voltage problem in low-voltage secondary distribution networks. For example, the authors in [6] have found that if DG units are not placed properly, there might be unwanted low/high voltages at specific loads. Additionally, with high penetration of DG units in the distribution system, the voltage level increases. If the voltage rise is significant, it could violate the maximum voltage criteria, specifically in light loading conditions [13]. In order to avoid the aforesaid problems and maximize the benefits of the integration of DG units, it is critical to correctly size and locate them [14]. There is a plethora of research conducted to address the problems of DG units’ sizing and placement. Reference [15] carries out an extensive review of various methods employed for this purpose. Traditionally, shunt capacitors have widely been used as a major source of the reactive power support in distribution networks. Capacitors are employed for various purposes such as reducing power losses and improving the voltage profile [16]. Almost all the methods explained in [15] could be employed for sizing and placement of capacitors in distribution networks. In recent distribution systems, high penetration of DG units as well as presence of capacitor banks, have prompted the researchers to study and propose approaches for the simultaneous placement of DG units and capacitor banks. Indeed, it is critical to present a holistic approach in the selection of DG units and capacitor banks in order to avoid unwanted problems such as the imbalance between the generated reactive power by DG units and capacitor banks, and the reactive power needed by the grid [17]. The authors in [16] propose a probabilistic formulation for capacitor placement in distribution networks with high penetration of DG units. In their work, Genetic Algorithm (GA) has been used to solve the optimization problem. Their results show that with proper capacitor placement in a system with high penetration of DG units, a significant reduction in cost associated with the electricity losses could be achieved. In another attempt, the authors in [18] study the optimal placement of DG units and the proper allocation of capacitor banks simultaneously in distribution systems. The objective function defined in their work consists of three indices: active loss, reactive loss and voltage profile. The objective function is minimized employing GA. Also, the effectiveness of the proposed method is evaluated by comparing the voltage profile of buses for both cases of prior and after the implementation. In [19], the authors propose a new approach to minimize the loss in the system with the presence of DG units and capacitor banks at the same time. Bacterial Foraging Optimization Algorithm (BFOA) is employed to minimize the objective function. The results demonstrate that simultaneous DG and capacitor placement is more effective in minimizing power losses and improving the voltage profile. In this paper, a new approach for simultaneous allocation of capacitor banks and DG units is proposed. The advantage of the proposed method over the aforesaid works is that it provides a quantitative measure to identify whether placing a DG unit or a capacitor bank is more beneficial at each bus in order to attain the objectives. Besides, unlike the aforementioned works, which neglect the impact of unit allocation on power factor, the proposed method attempts to make improvement on power factor as one of its objectives. The organization of the paper begins with introducing the approach in section II. Afterwards, a 49-bus distribution system is introduced in section III. This section, also, provides a case study to evaluate the performance of the proposed method. Moreover, the results are presented and discussed. Section IV closes the paper by drawing conclusions. II. M ETHODOLOGY The allocation of capacitor banks and DG units in the distribution system could be made to accomplish different goals. They include power loss reduction, voltage profile improvement, power factor correction, load balancing, and etc. In this paper, the goal is to concurrently place capacitor banks and DG units such that 1) total real and reactive losses of the system are reduced, 2) voltage profile is improved, and 3) the power factor for the total demand is improved. To carry out such task, six indices are defined as in (1) to (6). • Real and reactive power loss indices for DG unit and capacitor bank, respectively: P LDGi P IDGi = (1) PL QIDGi = P ICi = QLDGi QL (2) P LCi PL (3) QICi = • QLCi QL (4) Voltage profile index for DG unit and capacitor bank: V P Ii = max (1 − |Vj |) (5) j=1 to n • Power factor index for DG unit and capacitor bank: P F Ii = max (1 − P F ) (6) Where: PL Total real loss before DG/Cap. placement Total real loss after DG placement at bus i PLDGi QL Total reactive loss before DG/Cap. placement Total reactive loss after DG placement at bus i QLDGi Total real loss after Cap. placement at bus i PLCi Total reactive loss after Cap. placement at bus i QLCi Voltage magnitude of bus j |Vj | n Total number of buses PF Power factor percentage of the total demand Indices that are defined in (1), (2) and (5) were previously introduced in [20]. Two overall indices are defined from the aforementioned indices as in (7) and (8). OIDGi = w1 ·P IDGi +w2 ·QIDGi +w5 ·V P Ii +w6 ·P F Ii (7) OICi = w3 · P ICi + w4 · QICi + w5 · V P Ii + w6 · P F Ii (8) Where, wi is weight coefficient assigned to indices and sum total of the weights is one. The weight coefficients are to be selected based on the priorities of objectives. These indices are used to evaluate the impact of DG and capacitor placement on real, reactive power losses, voltage profile and power factor percentage of the total demand. It is obvious that a lower value for each index is desirable. The overall indices presented in (7) and (8) are a combination of active loss, reactive loss, voltage profile and power factor indices and are used to determine the best locations for placement of units. Moreover, they are employed to identify whether placing a DG unit or a capacitor bank is more beneficial at each bus (i.e for each bus i, if OIDGi < OICi , placing a DG unit at that bus would be more beneficial in terms of reducing losses, improving voltage profile and power factor for total demand). The proposed approach, which is illustrated in Fig.1, includes the following steps. 1) Power flow analysis is carried out and bus voltages are computed; 2) Buses are ranked according to the voltage profile from the lowest to the highest; 3) Buses with voltage below the limit are selected.If all buses have voltage above the limit, then buses with voltage less than the average voltage are selected.Indeed, this selection will reduce the search space for the purpose of decreasing the computational burden; 4) A capacitor with initial value of 1 p.u (reactive power) is placed at the selected buses one at a time, and the OICi Start Run the Power Flow Step1 Rank buses according to voltage magnitude Step2 Yes No Are there buses with Vi <Vmin? Step3 Select buses with Vi < Vmin Select buses with Vi < Vavg Add DG unit to bus i and calculate OIDGi Add capacitor to bus i and calculate OICi Fig. 2: Schematic of the test system DG unit and Capacitor Allocation Step4 base kVA is 10 kVA. Also, the current carrying capacity of branches 1-5 is 400A, 32-35 and 38-45 is 300A and for all other branches is 200A. The complete line and load data for the test system is provided in appendix A. Capacitor or DG unit Decision Sort the buses according to their OICi and OIDGi values Step5 Yes Based on the limits on numbers of units, place DG or capacitor for achieved locations in each branch Increase the size of units OIDGi < OICi DG is better option for bus i No Capacitor is better option for bus i No Are Constraints satisfied? Yes End Fig. 1: Algorithm for the proposed method is calculated. Similarly, a DG unit with unity power factor and initial value of 1 p.u (real power) is placed at the selected buses one at a time, and the OIDGi is computed; 5) The buses are sorted according to their OICi and OIDGi values. The buses with the lowest overall index value in each branch have the highest priority for capacitor and DG unit placement. Also, at this step, it could be determined which of the capacitor bank or DG unit provides a better result by comparing the OIDGi and OICi values; 6) Based on the constraints on costs or number of allowed capacitor banks or DG units, the number of units is decided and the placement is performed; 7) The size of DG units and capacitor banks are adjusted until all electrical requirements are satisfied. III. M ETHOD I MPLEMENTATION In what follows, for representation and validation purposes, the method is applied on a test system. A. Test system A modified version of the system introduced in [21] is used to perform the analysis. The schematic of the modified system is demonstrated in Fig 2. The system is a 49-bus system. The substation (S/S) voltage is assumed to be 12.66kV and the B. Case Study In order to apply the proposed method on the test system, the algorithm is implemented in MATLAB. As it was discussed, the first step is to carry out the power flow analysis to obtain voltage profile for all buses. Hence, the test system is simulated in the software and the power flow is performed. The resulting voltage profile for all buses is illustrated in Fig. 3. The buses, then, are ranked based on their voltage magnitude from the lowest to the highest values, and buses with the voltage magnitude less than the minimum are selected. In this case study, V min is assumed to be 0.98 p.u. Table I shows the buses with voltages less than 0.98 p.u. According to Table I, it is observed that there are 25 buses that have voltage magnitude less than the minimum. Fig. 3: Voltage profile for test system TABLE I: BUSES WITH VOLTAGE LESS THAN V min Bus No. 45 44 43 42 41 18 17 16 15 14 13 12 11 Voltage (p.u.) 0.922511 0.922992 0.924914 0.925157 0.935629 0.960723 0.960741 0.96096 0.96117 0.961176 0.962317 0.962325 0.963133 Bus No. 10 9 49 48 40 8 47 46 7 39 6 38 Voltage (p.u.) 0.966257 0.968919 0.971294 0.971295 0.971323 0.971605 0.974477 0.974478 0.974531 0.975105 0.975556 0.977851 TABLE II: VALUE OF THE WEIGHTS Weight Value w1 0.33 w2 0.22 w3 0.33 w4 0.22 w5 0.33 w6 0.11 TABLE III: INDEX VALUES FOR DG PLACEMENT Bus 45 44 43 42 41 18 17 16 15 14 13 12 11 10 9 49 48 40 8 47 46 7 39 6 38 PIDGi 0.7277 0.7181 0.7169 0.7169 0.7570 0.9102 0.9084 0.8994 0.8952 0.8952 0.8922 0.8922 0.8922 0.8958 0.8982 0.9072 0.9072 0.8952 0.9012 0.9108 0.9102 0.9090 0.9084 0.9120 0.9180 QIDGi 0.7500 0.7396 0.7383 0.7383 0.7759 0.9028 0.9015 0.8950 0.8924 0.8924 0.8898 0.8898 0.8898 0.8924 0.8937 0.9002 0.9002 0.8782 0.8963 0.9028 0.9028 0.9015 0.8937 0.9028 0.9041 VPIi 0.0583 0.0582 0.0605 0.0609 0.0637 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0748 0.0728 0.0748 0.0748 0.0748 0.0748 0.0736 0.0748 0.0743 PFIi 0.1811 0.1812 0.1812 0.1812 0.1810 0.1800 0.1800 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1801 0.1800 0.1800 0.1800 OIDGi 0.4488 0.4433 0.4433 0.4434 0.4661 0.5490 0.5481 0.5436 0.5417 0.5417 0.5401 0.5401 0.5401 0.5419 0.5430 0.5474 0.5474 0.5378 0.5445 0.5491 0.5489 0.5483 0.5459 0.5495 0.5517 0.62 0.59 OICi OIDGi 0.56 Overall Index Value The algorithm continues with placement of one capacitor bank with the initial value of 1p.u at each bus one at a time. PICi , QICi , VPI i , PFI i and OICi indices are then calculated. As it was mentioned, for the purpose of calculating the overall index value, the weights (wi ) are to be selected based on the priorities of objectives. The values of weights for this case study are presented in Table II. Next, the same procedure is followed for DG unit and PIDGi , QIDGi , VPI i ,PFI i and OIDGi are computed. The complete results for all indices for both cases of DG unit and capacitor bank placements are presented in Tables III and IV. For illustration purpose, the overal indices’ values achieved for DG units and capacitor banks at each bus are shown and compared in Fig.4 By sorting the buses according to their overall index values for both capacitor banks and DG units the locations having high priority for placement are determined. Table V sorts the overall index values (multiplied by 100) for capacitor and DG units. The values are scaled (i.e. multiplied by 100). According to Tables III, IV and V, the following observations can be made. • DG units provide lower overall index values for all buses in comparison with capacitor banks; as a result, DG units deliver better overall performance. • DG units show better results for real and reactive power loss reduction and voltage profile improvement as their PIDGi , QIDGi and VPI i indices’ values are lower compared to that for capacitor banks. • Capacitors deliver better performance for power factor 0.53 0.5 0.47 0.44 0.41 0.38 0.35 45 44 43 42 41 18 17 16 15 14 13 12 11 10 9 49 48 40 8 47 46 7 39 6 38 Bus Number Fig. 4: Illustration of overal index values for different buses improvement as their PFI i is lower compared to this value for DG units. • The best place for DG placement is bus 44, while the best location for capacitor bank placement is bus 42. • In the longest branch (buses 1 to 18), the best location for DG unit placement is bus 13, whereas for the capacitor bank placement, the best location is bus 8. • Although a considerable voltage drop is observed in bus 18, this bus gets low priority for adding DG units and capacitor banks. In this paper, two DG units and one capacitor bank are employed to show the improvements compared to the base case. Although, as it was demonstrated, DG units deliver better overall performance than capacitor banks at all buses, due to possible limitations such as availability of DG units, it is decided to use at least one capacitor bank. Also, it is worth mentioning that cost of units could be a major concern; nevertheless, in this paper, selection of the units is based on the defined overall index values, which does not include cost evaluation. The DG units are allocated to buses 44 and 13 and the capacitor bank is placed at bus 8. As a matter of fact, as it TABLE IV: INDEX VALUES FOR CAP. PLACEMENT Bus 45 44 43 42 41 18 17 16 15 14 13 12 11 10 9 49 48 40 8 47 46 7 39 6 38 PICi 0.8318 0.8282 0.8264 0.8258 0.8491 0.9640 0.9622 0.9533 0.9491 0.9491 0.9449 0.9449 0.9443 0.9425 0.9413 0.9461 0.9461 0.9335 0.9401 0.9449 0.9449 0.9431 0.9413 0.9449 0.9473 QICi 0.8497 0.8419 0.8393 0.8393 0.8601 0.9533 0.9520 0.9455 0.9430 0.9430 0.9404 0.9404 0.9391 0.9378 0.9365 0.9404 0.9404 0.9235 0.9365 0.9391 0.9391 0.9378 0.9326 0.9391 0.9391 VPIi 0.0688 0.0699 0.0711 0.0713 0.0723 0.0762 0.0762 0.0761 0.0761 0.0761 0.0761 0.0761 0.0761 0.0761 0.0761 0.0761 0.0761 0.0751 0.0761 0.0761 0.0761 0.0761 0.0755 0.0761 0.0758 PFIi 0.1352 0.1353 0.1353 0.1353 0.1342 0.1309 0.1309 0.1310 0.1311 0.1311 0.1310 0.1310 0.1310 0.1308 0.1306 0.1304 0.1304 0.1305 0.1305 0.1302 0.1302 0.1302 0.1302 0.1301 0.1299 OICi 0.5040 0.5015 0.5007 0.5006 0.5132 0.5731 0.5722 0.5678 0.5658 0.5658 0.5638 0.5638 0.5634 0.5625 0.5617 0.5642 0.5642 0.5559 0.5613 0.5635 0.5635 0.5626 0.5607 0.5635 0.5641 TABLE V: COMPARING OVERALL INDEX VALUES FOR DG/CAPS. Bus 44 43 42 45 41 40 13 15 10 9 16 8 39 49 17 7 46 18 47 6 38 OIDGi 44.33060769 44.33828213 44.34881399 44.88158179 46.61267613 53.78752192 54.01530568 54.17261688 54.19256501 54.30114282 54.36982435 54.45582105 54.59965553 54.74429115 54.81186157 54.83028785 54.89896938 54.90049124 54.91891752 54.95770267 55.1701715 Bus 42 43 44 45 41 40 39 8 9 10 7 11 6 47 13 38 49 15 16 17 18 OICi 50.06218 50.07686 50.15478 50.40921 51.32272 55.59956 56.07022 56.13844 56.17945 56.25035 56.26363 56.34121 56.35115 56.35226 56.38994 56.41819 56.42317 56.58826 56.78435 57.22902 57.31765 was demonstrated, bus 44 is the best place for DG placement; therefore, one of the available DG units would be placed at this bus. Moreover, as it was explained earlier, by looking at the longest branch (buses 1 to 18), it is understood that the best location for DG placement is bus 13. Hence, the second available DG unit will be placed at this bus. For the capacitor bank, the best location for placement is bus 42; furthermore, in the longest branch bus 8 has the highest priority. It is decided to place the capacitor in the longest branch; consequently, it is placed at bus 8. Finally, the values for all units are adjusted until all electrical requirements (i.e. voltage, current and power flow) are satisfied. The results of rating and location for units are summarized in Table VI. Considering the total load in the system and ratings of units provided in Table VI, DG penetration would be 55.3%. After allocation of the units in the proposed locations, again, the power flow analysis is performed. The results of voltage profile, real and reactive power losses and power factor percentage value for total demand are compared with the base case in Figs. 5 through 7, respectively. Based on Fig. 5, it is observed that the proposed placement scheme significantly improves the voltage profile. Moreover, there is a dramatic decrease in real and reactive losses after employment of the proposed method as demonstrated in Fig.6. Finally, according to Fig. 7, the power factor value for total demand is increased from 0.82 to 0.915. Hence, it is concluded that the proposed method is able to effectively select appropriate buses for DG unit and capacitor bank placement. TABLE VI: RATING AND LOCATION FOR SELECTED UNITS Unit DG DG Capacitor Bank Bus 44 13 8 Rating 1600 kW 500 kW 1000 kvar Fig. 5: Comparing voltage profile before and after implementation of the method Fig. 6: Comparing losses before and after implementation of the method Fig. 7: Comparing power factor before and after implementation of the method IV. C ONCLUSION In this paper, a new method for concurrent placement of DG units and allocation of capacitor banks was proposed. The objective was to reduce the total real and reactive power losses, improve the voltage profile and power factor. Moreover, the method was developed such that it is capable of indicating which of DG unit and capacitor bank is a better option to be allocated to any bus in the system. In order to propose the method, eight indices were defined and an algorithm was developed. For representation and validation purposes the method was applied on a 49-bus distribution system. Then, the algorithm was followed step by step and the best locations for installing the DG units and capacitor banks on each branch were determined. Moreover, the indices defined for DG units and capacitor banks were compared with each other and for each bus it was indicated which of DG unit or capacitor bank delivers better performance for each objective. Then, two DG units and one capacitor bank were placed and sized such that all electrical constraints were satisfied. Finally, by analyzing and comparing the results of voltage profile, power losses, and power factor for base case and proposed method, the desirable performance of the method was demonstrated. As a future study, the authors have plan to define an index for cost and include it in the overall index for both DG units and capacitor banks, and investigate its effects on the results. A PPENDIX A The complete line and load data (sending end and receiving end buses, impedance and load values) for the test system is provided in Table VII. TABLE VII: DATA FOR THE TEST SYSTEM Sending End S/S 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 19 20 21 22 23 1 25 26 27 28 29 30 2 32 33 34 4 36 5 38 39 40 41 42 43 Receiving End 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 R (Ω) 0.001 0.0015 0.7721 0.0922 0.0493 0.819 0.1872 0.7114 1.03 1.044 1.2546 0.3744 0.0047 0.8798 0.014 0.5054 1.0577 0.1732 0.0044 0.064 0.819 0.839 1.708 1.474 0.0044 0.064 0.1357 0.0018 1.0793 0.1181 0.0009 0.0034 0.0851 0.2898 0.0822 0.0928 0.3319 0.174 0.203 0.2842 2.9692 0.8936 0.0974 0.8555 X (Ω) 0.0024 0.0036 0.4099 0.047 0.0251 0.2707 0.0619 0.2351 0.34 0.345 0.4146 0.1238 0.0016 0.2902 0.0046 0.1671 0.3496 0.0572 0.0108 0.1565 0.2707 0.2816 0.5646 0.4873 0.0108 0.1565 0.1585 0.0021 1.261 0.1489 0.0012 0.0084 0.2083 0.7091 0.2011 0.0473 0.1114 0.0886 0.1034 0.1447 1.0406 0.3757 0.0496 0.4357 Receiving End Load P Q (kW) (kVar) 0 0 0 0 40.4 30 75 54 30 22 28 19 145 104 145 104 8 5 8 5.5 45.5 40 60 35 60 35 114 81 5 3.5 28 20 14 10 14 10 26 18.6 26 18.6 0 0 14 10 19.5 14 6 4 26 18.55 26 18.55 24 17 24 17 6 4.3 39.22 26.3 39.22 26.3 0 0 79 56.4 385 275 385 275 40.5 28.3 3.6 2.7 4.35 3.5 26.4 19 24 17.2 100 72 1244 888 32 23 227 162 R EFERENCES [1] F. Blaabjerg, R. Teodorescu, M. Liserre, and A. V. Timbus, “Overview of Control and Grid Synchronization for Distributed Power Generation Systems,” IEEE Transactions on Industrial Electronics, vol. 53, no. 5, pp. 1398–1409, Oct 2006. [2] J. M. Guerrero, F. Blaabjerg, T. Zhelev, K. Hemmes, E. Monmasson, S. Jemei, M. P. Comech, R. Granadino, and J. I. Frau, “Distributed Generation: Toward a New Energy Paradigm,” IEEE Industrial Electronics Magazine, vol. 4, no. 1, pp. 52–64, March 2010. [3] H. B. Puttgen, P. R. MacGregor, and F. C. Lambert, “Distributed generation: Semantic hype or the dawn of a new era?” IEEE Power and Energy Magazine, vol. 1, no. 1, pp. 22–29, Jan 2003. [4] R. C. Dugan and T. E. McDermott, “Distributed Generation,” IEEE Industry Applications Magazine, vol. 8, no. 2, pp. 19–25, Mar 2002. [5] H. Kuang, S. Li, and Z. Wu, “Discussion on advantages and disadvantages of distributed generation connected to the grid,” in International Conference on Electrical and Control Engineering (ICECE), Sept 2011, pp. 170–173. [6] P. C. Chen, R. Salcedo, Q. Zhu, F. de Leon, D. Czarkowski, Z. P. Jiang, V. Spitsa, Z. Zabar, and R. E. Uosef, “Analysis of Voltage Profile Problems Due to the Penetration of Distributed Generation in LowVoltage Secondary Distribution Networks,” IEEE Transactions on Power Delivery, vol. 27, no. 4, pp. 2020–2028, Oct 2012. [7] K. Rahimi and B. Chowdhury, “A hybrid Approach to Improve the Resiliency of the Power Distribution System,” in North American Power Symposium (NAPS), Sept 2014. [8] M. Davoudi, V. Cecchi, and J. R. Agero, “Effects of Stiffness Factor on Bus Voltage Variations in the Presence of Intermittent Distributed Generation,” in North American Power Symposium (NAPS), Oct 2015. [9] I. N. Moghaddam, Z. Salami, and L. Easter, “Sensitivity Analysis of an Excitation System in Order to Simplify and Validate Dynamic Model Utilizing Plant Test Data,” in IEEE Transactions on Industry Applications, vol. 51, no. 4, July 2015, pp. 3435–3441. [10] M. Chamana, I. Mazhari, B. Parkhideh, and B. H. Chowdhury, “MultiMode Operation of Different PV/BESS Architectures in a Microgrid: Grid-tied and Island Mode,” in IEEE PES T&D Conference and Exposition, April 2014. [11] R. Yousefian and H. Monsef, “DG-Allocation Based on Reliability Indices by Means of Monte Carlo Simulation and AHP,” in 10th International Conference on Environment and Electrical Engineering (EEEIC), May 2011. [12] R. Morsali, N. Ghadimi, M. Karimi, and S. Mohajeryami, “Solving a Novel Multiobjective Placement Problem of Recloser and Distributed Generation Sources in Simultaneous Mode by Improved Harmony Search Algorithm,” in Complexity Journal, vol. 21, no. 1, July 2015, pp. 328–339. [13] M. Vaziri, M. Afzal, M. Zarghami, A. Yazdani, S. Vadhva, and F. Tavatli, “Voltage Impacts of DG on Distribution Grid with Voltage Regulators and SVCs,” in IEEE Green Technologies Conference, April 2013. [14] K. Zou, A. P. Agalgaonkar, K. M. Muttaqi, and S. Perera, “Voltage Support by Distributed Generation Units and Shunt Capacitors in Distribution Systems,” in IEEE Power Energy Society General Meeting, July 2009. [15] P. S. Georgilakis and N. D. Hatziargyriou, “Optimal Distributed Generation Placement in Power Distribution Networks: Models, Methods, and Future Research,” IEEE Transactions on Power Systems, vol. 28, no. 3, pp. 3420–3428, Aug 2013. [16] H. E. Z. Farag and E. F. El-Saadany, “Optimum shunt Capacitor Placement in Distribution Networks with High Penetration of Renewable Energy Resources Using Genetic Algorithms,” in IEEE PES Innovative Smart Grid Technologies, Oct 2014. [17] A. C. Morais, J. Pascoal, and P. Cruz, “Optimizing Capacitor Banks Management in Distribution Networks, with Large Presence of Distributed Generation,” in 8th International Conference on the European Energy Market (EEM), May 2011. [18] M. Kalantari and A. Kazemi, “Placement of Distributed Generation Unit and Capacitor Allocation in Distribution Systems Using Genetic Algorithm,” in 10th International Conference on Environment and Electrical Engineering (EEEIC), May 2011. [19] M. I. A and K. M, “Optimal Distributed Generation and Capacitor Placement in Power Distribution Networks for Power Loss Minimization,” in International Conference on Advances in Electrical Engineering (ICAEE), Jan 2014. [20] D. Singh, D. Singh, and K. S. Verma, “Multiobjective optimization for dg planning with load models,” IEEE Transactions on Power Systems, vol. 24, no. 1, pp. 427–436, Feb 2009. [21] M. E. Baran and F. F. Wu, “Optimal capacitor placement on radial distribution systems,” IEEE Transactions on Power Delivery, vol. 4, no. 1, pp. 725–734, Jan 1989.