sliding mode control (smc) with anfis based pwm dual...
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Sliding Mode Control (SMC) with ANFIS based PWM Dual Inverter Based Grid Connected PV System: Modelling and
Performance analysis
By SK.HASEENA
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
N.B.K.R. INSTITUTE OF SCIENCE AND TECHNOLOGY (Autonomous)
MASTER OF TECHNOLOGY In
POWER SYSTEM
Project Guide
SK. MANJOOR AHAMAD M.Tech. Assistant professor.
Head of the Department Dr. S. SURESH REDDY M.Tech, Ph.D.
Professor
Abstract This paper proposes a novel robust sliding mode (SM) management for a cascaded two-level electrical converter (CTLI)-based grid connected electrical phenomenon (PV) system. The modelling and style of the management theme for the CTLI-based grid connected PV system is developed to provide active power and reactive power with variable star irradiance. A vector controller is developed keeping the most power delivery of the PV in thought. Two different change schemes have been thought of two style SM controllers and studied beneath similar operative things. Rather than the referred area vector PWM technique, an easy PWM modulation technique is employed for the operation of the planned SM controller. The performance of the SM controller is improved by victimization an adaptive hysteresis-band (HB) calculation. The controller performance is found to be satisfactory for each the schemes at
considered load and star irradiance level variations in simulation setting. The laboratory paradigm, operated with the planned controller is found to be capable of implementing the management algorithmic program with success within the thought of scenario.
Keywords—Photovoltaic (PV) system, multilevel inverter, Vector control, sliding mode control (SMC), distribution static compensator (Distribution-STATCOM
1. Introduction
In late years, the matrix associated PV framework is getting to be well known, in light of quickly expanding vitality request and the natural effects of petroleum derivative based vitality supply. Numerous creating nations have allowed, empowered, and indeed, even supported the combination of sustainable power source into the electrical network. It has been appeared in [1]-[3] the novel control
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electronic innovation assumes an exceptionally critical part in the circulated age (DG) and electrical matrix tie of sustainable power sources (PV framework, wind vitality and so on.). Some PV frameworks, utilizing power transformation for lattice interfacing have been proposed in [1], [3]-[5].The multilevel voltage source converters have developed as one of the favored decisions for medium voltage (MV) high-control applications because of a few focal points [6], [7]. Probably the most famous topologies of multilevel voltage-source converters are neutral point or then again diode-cinched converters (NPC), flying-capacitor (FC) converters and fell H-Bridge converters (CHB) [5], [7], [8]. The fell H-connect converter gets expansive consideration among these topologies, because of the secluded circuit format [9]-[10]. The significant preferred standpoint of CHB over other topologies is a negligible prerequisite of dc sources; the number of levels in the yield voltage can be expanded. The value of CTLI-based framework associated PV framework is lessened current and voltage music. Besides, the dv dt push is decreased, which is vital for high-control applications and higher excess exchanging state blends, contrasted with single-inverter for same yield voltage levels [5]. In [5] confined CTLI in low recurrence are utilized. The CTLI topology related with line-recurrence transformer has been proposed in [5], [9]. In the present investigation, likewise line recurrence transformers are utilized at the yield of the PV provided CTLI. Different control techniques are accessible in writing to control the converters, fusing the space vector balance (SVM) [10] and a PWM with stage moved bearers inside every H-extension of each multilevel stage leg Sliding Mode Control (SMC) of PWM Dual Inverter Based Grid Connected PV System: Displaying and Performance examination. In any case, one of the vigorous and dynamic control procedures is the sliding mode control (SMC). This control is a sort of nonlinear control, which has been produced essentially for the control of variable structure frameworks (VSS). These days, SMC is utilized in view of its few points of interest. Such properties make SMC very appropriate for applications in control converters and their wide usage in mechanical applications, e.g., electrical drives, high-voltage and high power applications, which require multilevel inverters or parallel inverters [5] as VSIs, dc-dc converters and so forth. The SM control experiences jabbering issue, which prompts variable and high recurrence exchanging in the converter. This marvel expands
control misfortunes and furthermore produces extreme electromagnetic similarity (EMC) clamor. The jabbering impact is controllable through the level of the hysteresis band in the hysteresis modulator of the SM controller. In the writing, CTLI topology has been proposed for distinctive applications [5], [6], [9]. This paper, manages the demonstrating of the CTLI based framework associated photovoltaic framework. The SMC is proposed for control of the yield streams of this CTLI. The control of the capacitor voltage is produced utilizing a vector control plot. In this work, the PV modules are intended to deliver a dc voltage of 48 V under appraised Indian sun powered irradiance. The inverter, in any case, is associated with an appropriation framework of three-stage air conditioning 400 V (line to line). The circuit-based model of a PV exhibit that can be executed in any recreation condition is proposed. In the present contemplate, single diode model of sun based cell is utilized after the scientific model created. The Photovoltaic frameworks are associated with the CTLI, and inverter yield to the low voltage (LV) side of an open winding three-stage transformer. The total power conspire is appeared in Fig. 1. The paper talks about the issue with following commitments: I) Two detached PV sources are intended to supply dynamic control at 48 V at a typical Indian sun oriented irradiance. This guarantees the most extreme power conveyance of the framework at evaluated condition. ii) A novel SM control plot is proposed so that the CTLI based framework would work under factor sun oriented irradiance levels and furthermore without sunlight based irradiance (as Distribution STATCOM). iii) The controllers are composed and tried for two diverse exchanging plans, a) Two-Level Switching and b) Forced Switching.
Fig. 1. Power circuit of the photovoltaic system with cascaded
two-level inverter
iv)To enhance the execution of SMC, the present work builds up a precise versatile methodology to ascertain the band of the hysteresis comparators.
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v) The info sun based irradiance is changed and furthermore diminished to zero to set up the task of the control with variable level of dynamic power supply and responsive control supply. vi) The tweak system for the CTLI is set up with a basic PWM system as opposed to alluding Space Vector tweak strategy. vii) The CTLI based power supply utilizing the proposed SMC is tried progressively independent mode through a research center model. The paper is sorted out as takes after: In Section II exhibits a numerical model lattice associated PV framework. The framework setup is given in Section III. Reenactment comes about taken after by dialog are introduced in Section IV. It too portrays the exploratory framework and results for the ongoing usage of SMC. At long last, the conclusions that have been drawn from the present work are abridged in Section V. II. MATHEMATICAL MODELLING OF THE SYSTEM The characteristic equation of PV cells is given by (1)
The equivalent circuit determined from the equation is used for the simulation model, is shown in Fig. 2. The parameter values are
. If a string has M identical modules, N identical PV strings can be in parallel to build a PV array containing PV modules. The complete multidimensional array model equation is shown in (2).
The number of cells connected in series to form one set, and the number of sets connected in parallel to form one array has been considered to provide maximum power at 48 V at the normal Indian solar irradiance. Power rating of the inverter is taken as the available output power at different output voltage is shown in Fig. 3. Here the output power is found to be maximum at 48 V with fixed solar irradiance. 2.5 kW
Fig.2. Equivalent circuit of PV cell
Fig. 3. Power-Voltage characteristics for the PV systemAccordingly, the controllers are designed to maintain the total PV output voltage of the two inverters (as shown in Fig. 1) at 96 V, to ensure maximum power delivery by the system.
A. CTLI model For the considered power scheme, the voltage across a, b and c windings are as follows:
Where are first inverter pole voltages
and are second inverter pole voltages. Assuming ideal power switches, the output voltage of the CTLI is obtained as (3), (4) and (5) which can be rewritten in matrix form as (6).
The design of sliding-mode control requires two conditions to be satisfied, namely, reaching and sliding phases. Switching surface, which will be called here onward as switching function sij, is defined by the following control law: Six switching
functions can be obtained as follows
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Thus, the three- phase output voltages of the CTLI related to the switching states can be expressed as:
B. Vector control:
The two-axis representation of the supply voltages can be formed as:
Here, . The d-q axis of the used vector control are derived following
The equivalent circuit for ‘a’ phase is shown in Fig. 5 in which �� is the grid voltage, R is the loss representing resistance, L is the leakage inductance of
transformer windings, is the voltage across the primary of the transformer. The transformer is step-up with turn ratio 1: n. Applying KVL for ‘a’, ’b’ and ‘c’ phases
, R� , and �� are considered to be equal to R and the �� , �� , and �� are equal to L. Hence,
Fig.4. Vector diagram of the voltage
Fig.5. Single phase equivalent circuit
Equation (17) is transformed to synchronously rotating reference frame as follows.
Where are d–q axes components of the cascaded inverter output current, respectively. The dynamics of the dc-link can be represented by:
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The reference value of d-axis current is generated from dc-link voltage controller. In this work, the reference the total of two dc voltage is kept at 96 V. C. Sliding mode control (SMC) The SMC comprises of a period differing state-input spasmodic control law that switches at a high recurrence starting with one consistent structure then onto the next, as per the introduce position of the state factors in the state space. The objective is to compel the elements of the framework under control to take after precisely what is wanted and pre-decided. SMC is especially intriguing because of its known attributes of vigor, framework arrange lessening, and suitability to the ON– OFF conduct of intensity switches. A standout amongst the most vital highlights of the sliding mode administration, in factor structure frameworks (VSS), is the capacity to accomplish reactions that are free of the framework parameters. The simple usage of SM control through hysteresis band does not require extra calculation or assistant hardware. There are fundamentally three methodologies in keeping the exchanging recurrence of the hysteresis tweak (HM) based SM controller steady. (a) Constant slope or timing capacities specifically into the controller. In this control plot the settled exchanging recurrence under every working condition, and controlled through fluctuating the incline/timing capacity. (b) Versatile control into the HM-based SM controller to balance the exchanging recurrence variety. (c) Constant exchanging recurrence SM controllers can likewise be gotten by utilizing PWM rather than HM. This work, exhibits the principle ventures to outline the SMC, connected to CTLI. A fell control structure with an inward current control circle and an external voltage control circle can The SMC comprises of a period changing state-input irregular control law that switches at a high recurrence starting with one ceaseless structure then onto the next, as per the show position of the state factors in the state space. The objective is to constrain the elements of the framework under control to take after precisely what is wanted and pre-decided. SMC is especially intriguing because of its known attributes of heartiness, framework arrange lessening, and propriety to the ON– OFF conduct of intensity switches. A standout amongst the most imperative highlights of the sliding mode administration, in factor structure frameworks (VSS), is the capacity to accomplish reactions that are free of the framework parameters. The simple usage of SM control through hysteresis band does not require extra calculation or helper hardware. There are essentially
three methodologies in keeping the exchanging recurrence of the hysteresis balance (HM)- based SM controller consistent . (a) Constant slope or timing capacities straightforwardly into the controller. In this control plot the settled exchanging recurrence under every single working condition, and controlled through changing the incline/timing capacity. (b) Versatile control into the HM-based SM controller to check the exchanging recurrence variety. (c) Constant exchanging recurrence SM controllers can likewise be acquired by utilizing PWM rather than HM. This work, introduces the primary strides to plan the SMC, connected to CTLI. A fell control structure with an internal current control circle and an external voltage control circle can take care of the control issue. The fell control structure is decided for simplicity of control acknowledgment and to misuse the movement division property of intensity converters. For control converters, the quick movement is ruled by the progression of the circle current, though the moderate movement originates from the progression of the yield voltage. The power converters inalienably incorporate exchanging gadgets, yielding a spasmodic control law. The voltage controls are generally acknowledged with standard vector control procedures; though the present control is actualized utilizing either sliding mode PWM or hysteresis control. Here the SM approach is connected to control the current blunder. The objective of the framework controller is to achieve voltage control of the inverter capacitors. This is achieved by controlling the dynamic and receptive power that streams into the network. Because of the qualities of SM controllers, for example, quick speed of reaction and unrivaled power to outer annoyances, this controlling philosophy has been received as a contrasting option to ordinary one. This SMC is outlined thinking about first as a chosen sliding surface and after that the control law driving the condition of the framework onto the sliding surface. The entryway signals for first and second inverters are created following hysteresis tweak procedure in the two exchanging plans, which are examined as takes after. Two-Level Switching: Scheme-I In this scheme, the inverter is operated under bipolar modulation with two levels of output 1 and -1. Fig. 6 shows the switching logic. For a particular phase of the two inverters, two switches are turned on, and the other two switches are turned off, in each cycle. If ��� is the switching frequency, then the switching loss per on-off is proportional to the switching
frequency and given by . The total
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switching loss is . A variable structure control (u) is described as
where se is the error between the actual value of the state variable and its corresponding reference. According to SM theory,sk crosses the switching surface at every switching instant, satisfying the SM conditions. Scheme I, as discussed above, is depicted in Fig. 7. Forced Switching: Scheme-II Fig. 8 introduces the schematic graph for Scheme II. Under this plan, prefixed exchanging recurrence can be gotten by contrasting the exchanging capacity and settled recurrence bearer flag. The bearer flag is triangular in nature. The adequacy of triangular flag is same as the hysteresis band. The procedure holds the heartiness properties of hysteresis controller while accomplishing the steady exchanging recurrence. Further, there is a base extent headed for the transporter motion at various frequencies.
Fig. 6. Two-level hysteresis modulation
Fig.7.Control block diagram of Scheme-I
Fig.8.Control block diagram of Scheme-II
The inverter may go into complex exchanging states underneath this size. Additionally, the following mistake and settling time increment with the expansion in the size of the transporter. In this way, it is fundamental to ascertain the ideal size of the bearer. Given the SMC properties concerning
reaction speed and heartiness to outside unsettling influences, thinking about the framework flow in (17), a SM controller is planned. From the stage accepted model (18), it can be seen that the controlled state factors Id and Iq have a relative level of one. Thusly, sliding surfaces appropriate to control factors d I and q I , can be made specifically relative to the state variable criticism blunders. The criticism mistakes are characterized as the distinction between
current references and the real streams, where every one of them are gotten from their separate d-q parts. The accompanying sliding surfaces ought to be zero in the wake of coming to sliding mode:
The control strategy must guarantee that the system trajectory moves towards and stays on the sliding surface from any initial condition. In order to achieve this strategy, the following stability condition must be achieved.
Accordingly the switching law is selected as
A similar procedure ib and ic is used for the and current error. The current control errors will be quantized using two hysteresis comparators. To improve the performance of SMC, the present work develops a systematic adaptive procedure to calculate the band of the hysteresis comparators. Adaptive HB calculation for SMC The calculation of hysteresis band is accomplished by considering a simple case with purely inductive load. The current reaches the upper and lower hysteresis band following Fig. 9 which, in turn, yields the voltage-current relationship as given by (28) and (29).
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Where t1 and t2 are the respective switching intervals, and fsw is the modulation frequency. Adding (31) and (32), and substituting (33) therein,
Further, subtracting (32) from (31), one obtains
Now, using (30), (34) and (35) it can be found that
Let be denoted by m, then (36) can be rewritten as
Fig. 9. Time-domain representation of two level hysteresis current
controls: (a) current waveforms with hysteresis control, and (b) Voltage source CTLI ac terminal voltage
This adaptive HB calculation technique is used to improve the PWM performances. III. SYSTEM CONFIGURATION
The CTLI topology based photovoltaic (PV) framework is delineated. The open-end twisting of a three-stage transformer low-voltage (LV) side is associated between the two inverters. The auxiliary is straightforwardly associated with the dispersion lattice. The transformer parameters are taken as appeared in the Table I [9], which is drawing sinusoidal current from the voltage waveform, as indicated later in the outcome segment. The thought about sun oriented irradiance deviation (in rate) from the underlying ordinary Indian irradiance level is appeared. At time 0.3 s, the sun based irradiance diminishes and the deviation gave is - 17.133 %, and at time 0.6 s, sun based brilliance is taken back to the appraised esteem. At the time 0.9s, sun based irradiance increments by 17.133 % and after that at the time 1.2s it is taken back to the appraised esteem.
4. An adaptive neuro-fuzzy inference
system
A adaptive neuro-fuzzy derivation network or versatile system based totally fuzzy deduction
network (ANFIS) is a sort of counterfeit neural gadget that relies upon on Takagi–Sugeno fuzzy
induction network. The approach changed into produced inside the mid Nineteen Nineties. Since it coordinates both neural structures and fuzzy motive
standards, it may probable seize the benefits of each in a solitary structure. Its induction network
compares to an arrangement of fuzzy IF–THEN comes to a decision that have learning capacity to inexact nonlinear capacities. Thus, ANFIS is thought
to be an all-inclusive estimator. For utilising the
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ANFIS as a part of a extra efficient and perfect way, you'll be able to make use of the exceptional
parameters received by hereditary calculation.ANFIS: Artificial Neuro-Fuzzy Inference
Systems
• ANFIS are a class of adaptive networks that are functionally equivalent to fuzzy inference
structures.
• ANFIS represent Sugeno e Tsukamoto fuzzy
fashions.
• ANFIS makes use of a hybrid studying set
of rules.
In the sector of synthetic intelligence neuro-fuzzy alludes to mixes of faux neural structures and fuzzy
rationale. Neuro-fuzzy hybridization brings approximately a half and half of astute community
that synergizes these approaches by using becoming a member of the human-like questioning fashion of fuzzy networks with the studying and connectionist
structure of neural systems. Neuro-fuzzy hybridization is genarelly named as Fuzzy Neural
Network (FNN) or Neuro-Fuzzy System (NFS) inside the writing. Neuro-fuzzy network (the more mainstream term is applied from this time ahead)
fuses the human-like questioning style of fuzzy networks the usage of fuzzy units and a semantic
model comprising of an arrangement of IF-THEN fuzzy standards. The primary fine of neuro-fuzzy
networks is that they are sizeable approximates with the capability to request interpretable IF-THEN ideas.
The exceptional of neuro-fuzzy networks includes
conflicting requirements in fuzzy displaying: interpretability as opposed to exactness. Practically
speakme, one of the two homes wins. The neuro-fuzzy in fuzzy demonstrating studies subject is separated into two zones: semantic fuzzy showing
that is centered on interpretability, for the maximum component the Mamdani model; and actual fuzzy
demonstrating this is centered round exactness, primarily the Takagi-Sugeno-Kang (TSK) model.
Representing fuzzification, fuzzy inference and
defuzzification via multi-layers feed-forward connectionist networks. It should be mentioned that
interpretability of the Mamdani-type neuro-fuzzy structures can be misplaced. To enhance the
interpretability of neuro-fuzzy systems, certain measures need to be taken, in which important components of interpretability of neuro-fuzzy
systems are also discussed.
A latest research line addresses the information movement mining case, where neuro-fuzzy systems
are sequentially up to date with new incoming samples on demand and on-the-fly. Thereby, machine
updates do not only encompass a recursive variation of model parameters, however also a dynamic evolution and pruning of model so that it will take
care of idea glide and dynamically changing machine conduct effectively and to keep the systems/models
"up-to-date" anytime.
Function member ship of input1
Function member ship of input2
Fig. 10ANFIS structure
Input/output low medium high low low Medium high medium Medium High high high high High high Table: ANFIS rules
5. Simulation result using pi controller
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Fig: 5.1 simulation result of solar deviation from the nominal PV model.
Fig: 5.2 output voltage of CTLI for scheme-I
Fig: 5.3 CTLI output current for scheme-I
Fig: 5.4 direct axis and quadrature pivot inverter current for scheme I
Fig: 5.5 direct axis grid and load current for scheme-I
Fig: 5.6 dc-link voltage for scheme-I
Fig: 5.6 output voltage of CTLI for scheme-II
Fig: 5.7 CTLI output current for scheme-II
Fig: 5.8 direct axis and quadrature axis inverter current for forced switching scheme
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Fig: 5.9 direct axis grid and load current for forced switching scheme
Fig: 5.10 dc-link voltage for forced switching scheme
Fig: 5.11 d-q axis inverter current for two level switching scheme
Fig: 5.12 grid and load q-axis current for two level switching scheme
Fig: 5.13 dc-link voltage for two level switching scheme
Fig: 5.14 d-q axis inverter current for forced switching scheme
Fig: 5.15 grid and load q-axis current forced switching scheme
Fig: 5.16 dc-link voltage for forced switching scheme.
Simulation by utilizing ANFIS Controller.
Fig: 5.17 Simulation results of sun based eviation from the ostensible PV demonstrate by utilizing ANFIS Controller.
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Fig: 5.18 output voltage of CTLIfor scheme-I by using ANFIS Controller
Fig: 5.19 CTLI output currentfor scheme-I by using ANFIS Controller
Fig: 5.20 direct axis and quadrature axis inverter urrentfor scheme-I by using ANFIS Controller
Fig: 5.21 direct axis grid and load currentfor scheme-Iby using ANFIS Controller
Fig: 5.22 dc-link voltagefor scheme-Iby using ANFIS Controller
Fig: 5.23 output voltage of CTLI for scheme-IIby using ANFIS Controller
Fig: 5.24 CTLI output current for scheme-IIby using ANFIS Controller
Fig: 5.25 direct axis and quadrature axis inverter current for constrained switching scheme by utilizing ANFIS Controller
Fig: 5.26 direct axis grid and load current for constrained switching scheme by using ANFIS Controller
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Fig: 5.27 dc-link voltage for constrained switching scheme by using ANFIS Controller
Fig: 5.28 d-q axis inverter current for two level switching scheme by utilizing ANFIS Controller
Fig: 5.29 grid and load q-axis current for two level switching scheme by using ANFIS Controller
Fig: 5.30 dc-link voltage for two level switching scheme by utilizing ANFIS Controller
Fig: 5.31 d-q axis inverter current for constrained switching scheme by using ANFIS Controller
Fig: 5.32 grid and load q-axis current constrained switching scheme by utilizing ANFIS Controller
Fig: 5.33 dc-link voltage for constrained switching schemeby utilizing ANFIS Controller
Conclusion
The present work utilizes a novel and powerful SM controller for CTLI based framework associated framework. Here the execution of the CTLI is discovered to be agreeable for two diverse control plans of SMC. The plan I and scheme– II, individually, think about hysteresis tweak and zero normal current blunder system to deliver the entryway signals. Both of the dynamic and the responsive power conveyance, in the nearness and nonattendance of sun oriented irradiance, are observed to be accomplished effectively. The controller is appeared to extricate most extreme power from the sun oriented PV modules by keeping up the dc-connect voltage at the coveted level for both the plans. The exhibitions under deviations in the information capacity to the inverters, because of changes in the accessibility of the sunlight based irradiance, and under half augmentation in stack, are observed to be attractive in nature. The THD of the network associated PV framework has been contemplated and observed to be impressively inside the point of confinement. It is fascinating to take note of that without sunlight based irradiance, both the control plans acting appropriation STATCOM mode providing responsive capacity to the network, keeping up the dc-connect voltage level also. This guarantees the use of the PV framework for both
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dynamic and responsive power conveyance with the proposed SM controller. The SMC is actualized effectively for the PV based power supply plot progressively through dSPACE 1104. The exploratory outcomes nearly coordinate with the reenactment brings about the thought about circumstance, which depicts the viability of the proposed controller.
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