Enhancement of Reactive Power Compensation in PV Grid System To Increase The PV Penetration Level In

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613

Enhancement of Reactive Power Capacity in Pv-Grid System to Increase Pv-Penetration Level of Smart Grid Scenario Chonduru Lakshminarayana1 P. Anilkumar2 G.N.S Vaibhav3 1,2,3 PVKK Institute of Technology Abstract— This project existing models force limits on the allowable feeder voltage variety in a disseminate environment. These stipulations must be regarded by the disseminated power generators (suppliers), which put a top on the entrance level. This project proposes a novel plan, where an assistant circuit (including an inverter and responsive force bank, RPB), in conjunction with a PVlattice framework, builds the framework’s receptive force pay limit up to 300% contrasted with the first or devoted VAR limit of the primary PV inverter. In resentment of utilizing just the routine discrete type of capaci-tor/inductor bank, the whole VAR reach can be controlled.

Key words: Common dc link, parallel operating, permanent magnet generator, wind power, zero-sequence cur-rents NOMENCLATURE               

Vdc Cp Lp Qstn IL & IC Fs Wci fSAx Wcv Wcxi Vd, Vq, Id, ,Iq L,r ed, eq

DC link voltage Capacitor bank Inductor bank Reactive power station Terminal voltages Switching frequency Cut off angular frequency Operating frequency Cut-off frequency Bandwidth Direct voltage component.

Qudrature voltage component.

Current components; Filter elements Voltage components I. INTRODUCTION

Generous and reliable ascent in burden interest has driven to new systems for expanding the generation of power, counting a plan of action to nearby (conveyed) era. At the same time, developing worries about ecological contamination have brought into centre the renewable vitality sources, for exam-ple, wind, sunlight based Photovoltaic (PV), tidal, and so on. A present's portion day burdens have an ex-tremely mind boggling and unusual nature. This in-corporates a major segment of mechanical burdens which are receptive in nature.

Furthermore, viable dispatch of receptive force.

Sheffield. have finished up on the need of brought together volt-VAR control by the utility that diminishes the voltage rise issues to empower high PV entrance. Some different creators have prescribed the utilization of PV-network inverters for responsive force Responsive force is a noteworthy impacting parameter in AC frameworks because of its effect on hold voltage profile. Disregarding eve-ry one of the discussions about D-STATCOM and PV inverters for pay obligation, actually countless still utilize discrete, switchable inductor and capaci-tor banks for responsive

force pay and voltage regulation as a sparing and basic arrangement de-spite the fact that it endures from the accompany-ing disadvantages: 1) Reactive force must be controlled in discrete strides due to which exact voltage regulation is un-realistic.

2) Switching of inductive and capacitive banks may bring about reverberation.

3) Switching ON of capacitor can prompt serious voltage plunge, taken after by homeless people and exchanging OFF of inductor is connected with high transient recuperation voltage issues.

In spite of the fact that the routine technique for receptive force remuneration utilizing D-STATCOM with discrete receptive force bank (RPB) is a plausible solution, it renders a poor element execution of receptive force control because of the nonattendance of feed forward pay. Further, non-concurring discrete receptive force bank ex-changing reasons voltage drifters. In addition, a committed DSTATCOM may not be practical.

To beat the above disadvantages to empower the utilization of capacitor what's more, inductor banks for responsive force pay, this paper proposes an-other framework design appeared in Fig. 1. In the proposed plan, the exchanging operation of the Reactive Force Banks (RPB) is incorporated with the control plan of the primary PV inverter to produce controlled responsive control over the whole range. Any shortage responsive force prerequisite of neighbourhood Electric Power System (EPS) is supplied

by RPB. Transient issues, which may emerge because of contrarily of line and bank terminal voltages, are overcome by the assistant con-verter in order to agree to guidelines, for example, The proposed plan, clarified in subtle elements in the following segment, offers the accompanying points of interest: 1) The proposed framework consolidates the STATCOM usefulness through the PV inverter it-self, without radically expanding the last's VA limit. Committed STATCOM is hindered for responsive force pay.

2) The store receptive force scope of PV inverter can be improved up to 300%.

3) The plan spreads complete controllable scope of receptive pay easily (and not in discrete strides) in spite of utilizing discrete banks. Hence consequent-ly, it can be utilized for exact voltage regulation.

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Enhancement of Reactive Power Capacity in Pv-Grid System to Increase Pv-Penetration Level of Smart Grid Scenario (IJSRD/Vol. 3/Issue 10/2015/168)

Fig. 1: Proposed power circuit of PV-DGS with auxiliary converter and RPB. Responsive force banks. The extra utilized for synchronization is of much lower VA limit as it is intended to supply just the force misfortunes in the bank.

Fig. 2: State machine diagram of the proposed re-active power enhancement scheme.

II. PROPOSED SYSTEM DESCRIPTION AND OPERATION The proposed PV station setup is appeared in Fig. 1. is the fundamental PV-network inverter, which may be a piece of a single-or two-stage topology. The DC join voltage, is controlled through, hence the PV created force might be spoken to by a proportional current source. An L-C channel is utilized for coupling of with the framework. Settled worth capacitor bank and inductor bank are utilized with their breakers and to give mass responsive force support.

The assistant converter is utilized with responsive force banks to manage the recent voltages equivalent to the network voltage by drawing force from the DC connection or PV source, while switch is open. The dynamic force attracted by to manage its AC yield voltage is not noteworthy in light of the fact that it just needs to bolster the misfortunes in the assistant system, including the inductor-capacitor bank.

The receptive force, infused by serves as input for controlling, and. The operation of the proposed force circuit [Fig. 1] is spoken to by a state machine outline in Fig. 2 that demonstrates the grouping of control ventures for every single conceivable condi-tion. Framework is so composed that the receptive force limit of is in any event a large portion of the individual limit of or bank. The arrangement of control of, and the different switches, as the work-ing conditions change, is as per the following: 1) During Low request: is open; and are close; is open; is initiated (for synchronization); controls and meets the responsive force request (i.e., ) 2) Under condition (1), if interest builds: then commitment builds and hits the maximum furthest reaches of

Fig. 3: Available reactive power control range at the various sections of the PV station.

1) When interest abatements taking after condition 2) contributes and hits as far as possible open; close; open; enacted, controls receptive force re-quest from station (i.e.,).

3) When interest expands ensuing to (say) condi-tion contributes and hits the lower point of con-finement of Off; close;.

III. DEMONSTRATING AND CONTROL DESIGN This segment portrays the displaying and outline of controllers for and [Fig. 1]. Both the inverters are controlled in the synchronously pivoting reference outline.

Circuitous current control (connected to the internal current circle) is actualized by controlling the terminal voltages of the two inverters. The PV inverter is matrix tied voltage source inverter. Its DC join voltage is controlled by the external volt-age regulation circle with the dynamic force seg-ment of current, upon actuation, keeps up the voltage of RPB equivalent to framework voltage by external AC voltage regulation.

Where are the direct and quadrature components of the transformed grid voltages. If voltage vector is aligned

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Enhancement of Reactive Power Capacity in Pv-Grid System to Increase Pv-Penetration Level of Smart Grid Scenario (IJSRD/Vol. 3/Issue 10/2015/168)

with axis, Are the current components; and are the filter elements of; are generated volt-age components with sinusoidal PWM switching technique and, where and Are the modulation indi-ces. Using (1), the model of with only filter is repre-sented by the following set of equations:

decision to give a stage help at the required cut-off recurrence of the addition plot. In like manner, the DC join volt-age controller has the accompanying structure:

The plant initially has a shaft at the source.

Consequently, with the extra necessary term added to the controller, the aggregate period of the circle ex-change capacity gets stretched out to: Accepting to be extensive, the DC join voltage may be considered stable over the area of hobby. By presenting new variables and , the accompanying exchange capacities can be acquired to plan the internal current control circles:

Where modulation indices md and mq are determined by using the following equations:

The proportion being small, the plant post is found near the fanciful hub and influences the transient reaction of the current.

Thus, close loop transfer function of the current control loop, can be reduced to first order with uni-ty gain as given below:

Outline of DC Link Voltage Controller for Controllers for the inward current circles were outlined ac-cepting that is genuinely steady amid the reference current following operation. By and by, it is unreal-istic to unite a vast capacitor at the DC join in light of the fact that firstly it is definitely not practical and furthermore a major capacitor will antagonis-tically influence the dynamic reaction of the DC join voltage.

The force equalization condition over the DC and AC ports of the PV inverter can be utilized to demonstrate the DC join by communicating the capacitor voltage as a component of (PV force yield) furthermore, (inverter force misfortune) as takes after:

The rakish speed of vectors is kept the same as that of to accomplish synchronous control of AC terminal voltages of manages an account with framework terminal voltages. Model (11) can be utilized to outline the controllers for the inward current circle utilizing (4)–(6).

Offers the DC join with. As the DC join voltage is directed through, the AC side variables of can be freely controlled, ex-pecting DC join voltage to be steady over the lo-cale of hobby. The transfer speed of the inward current control circle is picked, where the working recurrence of is. The AC voltage control of the RPB's utilizing synchronous outline change speaks to a fourth request control issue relating to the var-iables for and separately. The vector differential mathematical statement relating to the inductive RPB is as per the following.

Further, the capacitive and inductive banks form a common node with injecting current into it. Apply-ing KCL leads to the following vector equation:

Using (10) and (11), components of the vectors can be segregated and represented in the state space form as follows:

To avoid non-linearity, term can be considered as a state as well as an output variable of the plant model for the DC link voltage control. If is neglect-ed, (7) yields:

The food forward pay sign may be given by the PV-Maximum Power Point Tracking (MPPT) piece [Fig. 7].

Be that as it may, the misfortune segment can't be evaluated.

Subsequently, the compensator must incorporate an essential term.. For this situa-tion, a lead compensator is the best

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Enhancement of Reactive Power Capacity in Pv-Grid System to Increase Pv-Penetration Level of Smart Grid Scenario (IJSRD/Vol. 3/Issue 10/2015/168)

IV. EXECUTION EVALUATION OF RPB The proposed plan [Fig. 1] is demonstrated in MATLAB Simulink. The force converters are precisely spoken to by itemized switch models. To start with we examine the execution of the helper converter RPB setup. To contemplate the execution of inward current control and external Air conditioning voltage control of, ostensible frame-work voltage reference: is connected to the control unit Fig. 5(a) demonstrates that segments of yield voltage reliably track the reference inputs. This infers that the inward current control circles are working attractively.

Accordingly, supplies just the misfortune segment and another current part because of minor distinction between reactance estimations of and. Fig. 5(b) demonstrates the helper converter rating to be much littler contrasted with the primary PV inverter.

V. ASSESSMENT OF SYSTEM WITH ONLY CAPACITOR BANK Fig. 6 demonstrates the spiral feeder that was mimicked by assess the adequacy of the proposed receptive force upgrade plan. Different burdens are viewed as joined with transports 1–5 over the out-spread feeder. The proposed framework is inter-faced with transport no. 3. Grouping and steps depicted in Section III can be utilized to control both inductive and capacitive receptive force into the feeder. For show reason furthermore for explora-tion

Subsequently, the force circuit of the helper framework is adjusted to incorporate just the capacitor bank and switch .

A. Control Strategy The schematics of the complete PV station recep-tive force control methodology are appeared in Figs. 7(a), 7(b), where the compensators composed in Section III are utilized. As just capacitive RPB is considered, control of the RPB voltage gets im-proved, however the inward current control circles continue as before. The switch " operation is acknowledged utilizing the produced receptive force part of yield amid the procedure of station responsive force control as appeared in Fig. 7(a). The reference for responsive force segment of cur-rent, can either be acquired from the PCC transport voltage regulation utilizing suitable compensator as appeared in square in Fig. 7(a) or from the net commitment required for the responsive force re-muneration for the given feeder stacking as per square . of neighborhood EPS then again from the data about element conduct of voltage reaction of the transport as for receptive force infusion

The compensator for AC transport voltage regulation can be composed from the identical model given by (S)(S) (14) The response of the inner reactive power component of the main PV inverter, is governed by the designed current controlled plant

Fig. 6: Single line diagram of radial feeder to study the proposed auxiliary converter and reactive pow-er capability.

The data transmission of the external control circle of the station receptive force is intended to be littler contrasted with the internal current control circle's cut-off recurrence.

Consequently, in the district of Interest, the term can be approximated as takes after to dodge the subsidiary term from showing up in the food forward circle. Programming interface controller with food forward pay is observed to be suitable. For the fancied cut-off recurrence, , the controller parameters acquired utilizing (14), (15) are given by:

VI. SIMULATION RESULTS

Fig. 7: Control scheme for the proposed reactive power enhancement system with only capacitor bank and switch in operation. (a) Control. (b) Control.

Accommodation, it is expected that the feeder prerequisite is prevalently inductive receptive force.

Fig. 1: 3-Ph PV station voltages and A-Ph capacitor bank current without proposed control

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Enhancement of Reactive Power Capacity in Pv-Grid System to Increase Pv-Penetration Level of Smart Grid Scenario (IJSRD/Vol. 3/Issue 10/2015/168)

Fig. 2: 3-Ph PV station voltage and A-Ph capacitor bank current with proposed control.

Fig. 7: During highest contribution of capacitive reactive power by the station.

VII. CONCLUSION

Fig. 3: Line-to-line station voltages and that of capacitor bank.

After going through this review based on the given title, it has been concluded that issues of unreliable power quality, increased focus on re-newable energy, need for rural electrification, and focus on higher efficiency have resulted in more emphasis on developing micro grid infrastructure .Among various techniques reviewed and consider-ing future scope, more case studies of actual sites of MG can be done and some extended emphasis should be laid on issues of micro grid like protec-tion issues, power system stability and further the implementation of FACTS devices in existing mi-cro grid can help to maintain power quality and better power flow.

REFERENCES

Fig .4: When PV inverter is operating at unity power factor.

Fig. 5: During capacitive reactive power supply by the station.

Fig. 6: During capacitive reactive power supply by the station.

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