在低壓電網中，高度的太陽光電變流器滲透率將影響電網的穩定度與可靠度，所以併網型變流器需利用一些控制策略來維持、改善電網的電力品質，因此本研究提出一種新型的實虛功控制策略應用於併網型單級式三相太陽光電系統，目的是要維持共同耦合點(PCC)上的電壓變動率，此控制策略不只注入實功至電網，還會依電壓變動程度注入虛功至電網或從電網中吸收虛功以符合電力公司之規範，同時在不超過變流器的容量限制下，提出另一種考量經濟效益的控制策略，將發電用戶的實功輸出、虛功補償做適當的調整，使回售利益最大化的提升。此外，還提出可調變步長之改良型增量電導法以提升最大功率點追蹤法(MPPT)的追蹤速度與準確度。而本研究所使用的單級三相電流控制電壓源變流器(CCVSI)具有最大功率點追蹤與功率控制的能力。最後，利用模擬與實驗結果驗證所提出實虛功控制策略應用於併網型單級三相太陽光電系統在電壓變動時之成效。

High penetration level of the photovoltaic (PV) inverters in low voltage (LV) distribution grid will impact the stability and reliability of the grid. The main objective of the control strategy of the grid-connected inverter is to maintain or improve the grid stability, reliability and power quality. Therefore, in this study, a novel active and reactive power control strategy of a single-stage three-phase grid-connected photovoltaic (PV) system is proposed to mitigate the voltage variation at the point of common coupling (PCC). The single-stage three-phase grid-connected PV system introduces a current-controlled voltage-source inverter (CCVSI) to achieve the maximum power point tracking (MPPT) control of the PV panel and the function of power control. Moreover, a modified variable step-size incremental conductance (VSSIC) method is proposed to improve the tracking speed and accuracy of the MPPT control of the PV panel. Furthermore, the single-stage three-phase grid-connected PV system will inject or absorb the reactive power into or from the grid to mitigate the voltage variation at the PCC according to the grid codes. In the meantime, an economics optimization method is proposed to determine the control values of the active and reactive power with guaranteeing the output power of the three-phase inverter within the rating of itself. Finally, some experimental tests are realized to validate the effectiveness of the proposed control strategy.

[1] 經濟部能源局，永續能源政策綱領，2008。
[2] 經濟部能源局，綠色能源產業躍升計畫，2014。
[3] 台灣電力公司，http://www.taipower.com.tw/content/new_info/new_info-b49.aspx?LinkID=9。
[4] F. Blaabjerg, R. Teodorescu, M. Liserre, and A. V. Timbus, “Overview of control and grid synchronization for distributed power generation systems,” IEEE Trans. Ind. Electron., vol. 53, no. 5, pp. 1398-1409, Oct. 2006.
[5] S. Jain and V. Agarwal, “Comparison of the performance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems,” IET Electric Power Applications, vol. 1, no. 5, pp. 753–762, 2007.
[6] K. H. Hussein, I. Muta, T. Hoshino, and M. Osakada, “Maximum photovoltaic power tracking : an algorithm for rapidly changing atmospheric conditions,” IEE Proc. Gener. Transm. Distrib., vol. 142, no. 1, pp. 59-64, Jan. 1995.
[7] T. Esram and P. L. Chapman, “Comparison of photovoltaic array maximum power point tracking techniques,” IEEE Trans. Energy Convers., vol. 22, no 2, pp. 439-449, 2007.
[8] F. Liu, S. Duan, F. Liu, B. Liu, and Y. Kang, “A cariable step size INC MPPT method for PV Systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2622-2628, 2008.
[9] Y. T. Chen and J. H. Lai, “A novel variable step-size MPPT method for PV system with single sensor,” 9th IEEE Conference on Industrial Electronics and Applications, pp. 718-722, 2014.
[10] R. Yan and T. K. Saha, “Investigation of voltage stability for residential customers due to high photovoltaic penetration,” IEEE Trans. Power Syst., vol. 27, no. 2, pp. 651-661, May 2012.
[11] R. Tonkoski, D. Turcotte, and T. H. M. El-Fouly, “Impact of high PV penetration on voltage profiles in residential neighborhoods,” IEEE Trans. Sustainable Energy, vol. 3. no. 3, pp. 518-527, Jul. 2012.
[12] T. Beach, A. Kozinda, and V. Rao, “Advanced inverters for distributed PV: latent opportunities for localized reactive power compensation,” Cal x Clean Coalition Energy C226, 2013.
[13] E. Demirok, D. Sera, R. Teodorescu, P. Rodriguez, and U. Borup, “Clustered PV inverters in LV network: an overview of impacts and comparison of voltage control strategies,” IEEE Electrical Power & Energy Conf. (EPEC), pp. 1-6, Oct. 2009.
[14] R. Kabiri, D. G. Holmes, and B. P. McGrath, “The influence of PV inverter reactive power injection on grid voltage regulation,” 2014 IEEE 5th Inter. Sympos. on Power Electron. for Distributed Generation Systems (PEDG), pp. 1-8, Jun. 2014.
[15] M. N. Kabir, Y. mishra, G. Ledwich, Z. Y. Dong, and K. P. Wong, “Coordinated control of grid connected photovoltaic reactive power and battery energy storage systems to improve the voltage profile of a residential distribution feeder,” IEEE Trans. Ind. Informat., vol. 10, no. 2, pp. 967-977, May 2014.
[16] M. Fazeli, J. B. Ekanayake, P. M. Holland, and P. Igic, “Exploiting PV inverters to support local voltage - a small-signal model,” IEEE Trans. Energy Convers., vol. 29, no. 2, pp. 453-462, Jun. 2014.
[17] M. J. E. Alam, K. M. Muttaqi, and D. Sutanto, “A multi-mode control strategy for VAr support solar PV inverter reactive in distribution networks,” IEEE Trans. Power Syst., vol. 30, no. 3 pp. 1316-1326, May 2015.
[18] K. Ishaque, Z. Salam, M. Amjad, and S. Mekhulef, “An improved particle swarm optimization (PSO)–based MPPT for PV with reduced steady-state oscillation,” IEEE Trans. Power Electron., vol. 27, no. 8, pp. 3627-3638, Aug. 2012.
[19] 柯廷翰，考慮配電系統三相故障之具低電壓穿越能力之智慧型太陽光電系統，國立中央大學，碩士論文，2013年六月。
[20] 黃仲欽，交流電動機控制，交流電動機課程講義，民國97年。
[21] P. Rodriguez, A.V. Timbus, R. Teodorescu, M. Liserre, and F. Blaabjerg, “Flexible active power control of distributed power generation systems during grid faults,” IEEE Trans. Ind. Electron., vol. 54, no. 5, pp. 2583-2592, Oct. 2007.
[22] N. Mohan, T. M. Undeland, and W. P. Robbins, Power electronics, 1989.
[23] 使用手冊，可程控直流電源供應器(具太陽能電池陣列模擬) 62000H系列使用手冊，Chroma，2012。
[24] 呂宗翰，智慧型控制雙饋式感應風力發電系統之研製，國立中央大學，碩士論文，2010年六月。
[25] User Manual, User’s Manual PCR-LE series, KIKUSUI, Feb. 2013.
[26] S. Lundberg, “Electrical limiting factors for wind energy installations,” Master Dissertation, Chalmers University of Technology, Gothenburg, Sweden, 2000.
[27] Y. H. Yang and F. Blaabjerg, “A modified P&O MPPT algorithm for single phase PV systems based on deadbeat control,” in Proc. 6th IET Inter. Conf. Power Electronics, Machines and Drives, Mar. 2012.
[28] R. A. Mastromauro, M. Liserre, and A. Dell’Aquila, “Control issues in single-stage photovoltaic systems: MPPT, current and voltage control,” IEEE Trans. Ind. Inform., vol. 8, no. 2, pp. 241-254, 2012.
[29] M. A. G. de Brito, L. Galotto, L. P. Sampaio, G. de Azevedo e Melo, and
C. A. Canesin, “Evaluation of the main MPPT techniques for photovoltaic applications,” IEEE Trans. Ind. Electron., vol. 60, no. 3, pp. 1156-1166, Mar. 2013.
[30] F. Liu, S. Duan, F. Liu, B. Liu, and Y. Kang, “A variable step size INC MPPT method for PV systems,” IEEE Trans. Ind. Electron., vol. 55, no. 7, pp. 2622-2628, Jul. 2008.
[31] Q. Mei, M. Shan, and J. M. Guerrero, “A novel improved variable step-size incremental resistance MPPT method for PV system,” IEEE Trans. Ind. Electron., vol. 58, no. 6, pp. 2427-2434, Jun. 2011.
[32] 林志皇，獨立型光伏系統部分遮蔽之即時最大功率點追蹤法，國立聯合大學，碩士論文，2012年
[33] 台灣電力股份有限公司，再生能源發電系統併聯技術要點，2009。
[34] IEEE Std. 1547, Standard for Interconnecting Distributed Resources with Electric Power Systems.
[35] E.ON Netz GmbH, Grid Connection Regulations for High and Extra High Voltage.
[36] F. A. Viawan and D. Kaerlsson, “Coordinated voltage and reactive power c ontrol in the presence of distributed generation,” IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century., pp. 1-6, Jul. 2008.
[37] R. Kabiri, D. G. Holmes, and B. P. McGrath, “The influence of PV inverter reactive power injection on grid voltage regulation,” 2014 IEEE 5th Inter. Sympos. on Power Electron. for Distributed Generation Systems (PEDG)., pp. 1-8, Jun. 2014.
[38] R. Kabiri, D. G. Holmes, and B. P. McGrath, “LV grid voltage regulation using transformer electronic tap changing with PV inverter reactive power injection,” IEEE Journal of Emerging and Selected Topics in Power Electron., vol. 3, no. 4, pp. 1182-1192, Dec. 2015.
[39] Y. Wang, K. T. Tan, X. Y. Peng, and P. L. So, “Coordinated control of distributed energy storage systems for voltage regulation in distribution networks,” IEEE Trans. Power Del., vol. vol. pp, pp. 1, Early access, 2015.
[40] T. Beach, A. Kozinda, and V. Rao, “Advanced inverters for distributed PV: latent opportunities for localized reactive power compensation,” Cal x Clean Coalition Energy C226., pp. 1-28, 2013