دانلود ترجمه مقاله اصلاح انتقال و کیفیت قدرت آرایه فتوولتائیک گرید در بهساز يكپارچه كيفيت توان

بخشی از ترجمه:

چکیده :
در این مقاله، طرح ترکیبی UPQC و آرایه PV پیشنهاد می شود . سیستم پیشنهادی از اینورترهای سری و موازی، آرایه PV متصل شده به لینک DC بوسیله مبدل بوست که قادر به جبرانسازی کمبود ولتاژ و قطعی ولتاژ، هارمونیک ها و توان راکتیو در هر دو مد جزیره ای و اتصال به شبکه می باشد تشکیل می شود. سیستم پیشنهادی علاوه بر اینکه قابلیت بهبود کیفیت توان در نقطه کوپلینگ مشترک را داراست، قادر است به شبکه توان اکتیو تزریق کند.  همچنین می تواند بخشی از توان بار حساس را در طی قطعی ولتاژ فراهم کند. نتایج شبیه سازی در نرم افزار PSCAD/EMTDC نشان می دهد که سیستم ذکر شده به درستی عمل می کند.
مقدمه:
یکی از ساختارهای مقایسه ای توان الکتریکی، مبدل پشت به پشت می باشد. در رابطه با کنترل کردن ساختار، این مبدلها ممکن است عملکرد های متفاوتی در جبرانسازی داشته باشند. برای مثال، آنها می توانند بعنوان فیلترهای اکتیو سری یا موازی برای جبرانسازی سنکرون هارمونیک های جریان بار و نوسانات ولتاژ عمل کنند. این، بهساز یکپارچه کیفیت توان (UPQC) نامیده می شود.
UPQC بطور وسیعی توسط چندین محقق بعنوان یک دستگاه پایه برای کنترل کیفیت توان مطالعه شده است. وظیفه UPQC کاهش اغتشاشاتی است که بر عملکرد بارهای حساس تاثیر می گذارد. UPQC قادر به جبرانسازی کمبود و بیشبود ولتاژ، هارمونیک های ولتاژ و جریان با استفاده از اینورتر های موازی و سری می باشد. علیرغم این موضوع، UPQC قادر نیست قطعی ولتاژ و تزریق توان اکتیو به شبکه به علت اینکه در لینک DC اش منبع انرژی وجود ندارد را جبرانسازی کند.

بخشی از مقاله انگلیسی:

INTRODUCTIONOne of the comparative structures of the electric power is back to back converter. In respect to controllingstructure, these converters may have various operations in compensation. For example, they can operate asseries or shunt active filters for synchronous compensating the load current harmonics and voltage oscillation(Akagi et al, 2007). This is called unified power quality conditioner (UPQC) (Aredes and Watanabe, 1995).UPQC is greatly studied by several researchers as a basic device to control the power quality (Akagi andFujita, 1995),(Basu rt al, 2007),(Fujita and Akagi, 1998),(Chen et al, 2000),(Peng rt al, 1998). The duty ofUPQC is reducing perturbations which affect on the operation of sensitive loads. UPQC is able to compensatevoltage sag and swell, voltage and current harmonics using shunt and series inverters. In spite of this issue,UPQC is not able to compensate voltage interruption and active power injection to grid, because in its DC link,there is no energy source.The attention to distributed generating (DG) sources is increasing day by day. The reason is their importantroll they will likely play in the future of power systems (Blaabjerg et al, 2004),(Barker and deMello, 2000).Recently, several studies are accomplished in the field of connecting DGs to grid using power electronicconverters. Here, grid’s interface shunt inverters are considered more where the reason is low sensitiveness ofDGs to grid’s parameters and DG power transferring facility using this approach. Although DG needs morecontrols to reduce the problems like grid power quality and reliability, PV energy is one of the distributedgeneration sources which provides a part of human required energy nowadays and will provide in the future.The greatest share of applying this kind of energy in the future will be its usage in interconnected systems.Nowadays, European countries, has caused interconnected systems development in their countries by choosingsupporting policies (Watanable et al, 1998). In this paper, UPQC and PV combined system has been presented.UPQC introduced in (Chen et al, 2000) has the ability to compensate voltage sag and swell, harmonics andreactive power.In fig. 1 the general structure of grid connected PV systems is shown. The advantage of proposedcombined system is voltage interruption compensation and active power injection to grid in addition to thementioned abilities. Also, this proposed system has higher efficiency and functioning ability in compare withother common PVs and causes reduction in system’s total cost. Simulation results, using (PSCAD/EMTDC)software show that this proposed system operates correctly.MATERIALS AND METHODSUPQC has two shunt and series voltage source inverters which are as 3-phase 3-wire or 3-phase 4-wire.Shunt inverter is connected to point of common coupling (PCC) by shunt transformer and series inverter standsbetween source and coupling point by series transformer. Shunt inverter operates as current source and seriesinverter operates as voltage source.UPQC is able to compensate current’s harmonics, to compensate reactive power, voltage distortions andcontrol load flow but cannot compensate voltage interruption because of not having any sources.Common interconnected PV systems structure is as fig. 1 which is composed of PV array, DC/DC andDC/AC converters.In this paper a new structure is proposed for UPQC, where PV is connected to DC link in UPQC asenergy source. In this case, UPQC finds the ability of injecting power using PV to sensitive load during sourcevoltage interruption. Fig. 2 shows the configuration of proposed system. In this proposed system, twooperational modes are studied as follow:A. Interconnected mode; where PV transfers power to load and source.B. Islanding mode; where the source voltage is interrupted and PV provides a part of load power separately.Controller Designing:The controlling structure of proposed system is composed of three following parts:A. Shunt inverter controlB. Series inverter controlC. DC/DC converterControlling strategy is designed and applied for two interconnected and islanding modes. In interconnectedmode, source and PV provide the load power together while in islanding mode; PV transfers the power to theload lonely. By removing voltage interruption, system returns to interconnected mode.A. Shunt Inverter Control:In this paper, shunt inverter undertakes two main duties. First is compensating both current harmonicsgenerated by nonlinear load and reactive power, second is injecting active power generated by PV system. Theshunt inverter controlling system should be designed in a way that it would provide the ability of undertakingtwo above duties. Shunt inverter control calculates the compensation current for current harmonics and reactivepower when PV is out of the grid. The power loss caused by inverter operation should be considered in thiscalculation. Also, shunt inverter control undertakes the duty of (stabilizing) DC link voltage during seriesinverter operation to compensate voltage distortions. DC link capacitor voltage controlling loop is used hereby applying PI controller. Figure 4 shows the circuit block diagram of shunt inverter controlling.