The generation of electricity based on renewable energy sources, particularly Photovoltaic (PV) system has been greatly increased and it is simply instigated for both domestic and commercial uses. The power generated from the PV system is erratic and hence there is a need for an efficient converter to perform the extraction of maximum power. An improved interleaved Single-ended Primary Inductor-Converter (SEPIC) converter is employed in proposed work to extricate most of power from renewable source. This proposed converter minimizes ripples, reduces electromagnetic interference due to filter elements and the continuous input current improves the power output of PV panel. A Crow Search Algorithm (CSA) based Proportional Integral (PI) controller is utilized for controlling the converter switches effectively by optimizing the parameters of PI controller. The optimized PI controller reduces ripples present in Direct Current (DC) voltage, maintains constant voltage at proposed converter output and reduces overshoots with minimum settling and rise time. This voltage is given to single phase grid via

The world’s rising demand for electricity has improved the productivity and widespread use of renewable energy. Among most significant renewable energy sources utilized for power generation, solar PV array has attracted most of the researchers [

A

Design of sliding mode controller for photo voltaic MPPT is proposed. This is fed to SEPIC converter and it is applied to a broad variety of PV fed converters [

A Fuzzy Logic Control (FLC) based SEPIC for MPPT is proposed. With reduced voltage stress, this SEPIC has high stepped potential design. The Zeta converter’s output current is continuous with lesser output ripple compared to SEPIC and Cuk converters [

An improved interleaved DC-DC SEPIC converter is employed in proposed work. This converter boosts up the PV panel DC voltage. Conventionally PI controller is utilized for controlling DC link voltage. The parameters of PI are tuned by CSA. By optimizing PI controller with CSA, the ripples are reduced and constant voltage is maintained at proposed converter output with reduced settling time. This voltage is fed to

The proposed system’s schematic block representation presented in

The input voltage of

A solar cell is a tool used for conversion of photon energy into pollution-free electricity. The modules connected into series and parallel arrangements are responsible for producing clean and green electricity in order to create PV arrays. As a part of an electrical circuit, a single solar cell is depicted. It involves a p–n junction known as diode, a photocurrent generator illustrating the generation of light current and two resistors. One is arranged in series combination and another one in parallel defining the losses of Joule effect and recombination. This combination is then referred as a single model of PV cell diodes. The equivalent circuit of

The model of PV panel is expressed mathematically as,

Thus the physical performance of solar panel depends on resistance connected in shunt and series fashion, solar irradiation and temperature.

In solar PV application, converters that are commonly used have faced serious issues on high input current ripples. This issue is overcome by instigating improved interleaved SEPIC converter. An interleaved DC-DC SEPIC converter contains multi-converter phase shifting control signal that works at equal switching frequencies. As a DC–DC converter, it produces extra power, minimizes harmonic distortion, and reduces electromagnetic interference and the schematic representation is mentioned in

The proposed converter delivers an outstanding conversion of buck-boost with non-inverted output potential which is compared to other interleaving DC–DC converters and achieves greater energy efficiency with minimum elements. The output voltage

Thus the interleaved SEPIC converter performs efficient boosting of input DC voltage with the generation of reduced electromagnetic interference and ripples.

The PI controller parameters

Crows are regarded as clever birds having brilliant brain. The unfavorable condition is simply predicted by crows as they are having great capacity of face recognition. It will search for its food in an optimal manner by interacting with their families.

For instigating CSA, the parameters are regarded as follows.

No. of crows allocated as flock size is denoted as

Consider, crow

The steps included in the implementation of crow search algorithm are,

If the value of fitness function for DC link voltage of new crow location is greater than the value of memorized location, the crow updates its memory with the new location.

The obtained values from the CSA optimization indicates efficient tuning of PI controller parameters. This maintains a constant DC link voltage with minimized ripples and settling time. The flowchart representing this process is evidently provided in

Normally, synchronization methods are classified in to two types as mathematical analysis method and PLL method. Among these methods, adaptive filtering based phase locked loop method gains more attraction. A fundamental PLL is represented in

The structure of PLL contains PD, LP and VCO. If first order LPF is utilized, a small signal model of

From

The use of adaptive filter is another option for phase detection that perform self-adjusting of output using an error feedback loop.

Considering an ideal sinusoidal signal,

where,

Using PI controller

The

The solar array output voltage is fed to an improved interleaved DC-DC SEPIC converter. Due to temperature variation, PV panel output link voltage does not maintain constant value and causes the occurrence of ripples. The CSA based proportional integral controller for proposed converter optimizes PI controller parameters that maintains constant voltage at proposed converter, reduces ripples and settling time. This voltage is given to

The solar panel specifications are represented in

Components | Specifications |
---|---|

No. of panel | 15 |

Total no. of series cells | 36 |

Cell area | 125 mm × 31.25 mm |

Open circuited voltage | 21.4 V |

Operating current | 5.8 A |

Short circuited current | 6.2 A |

Temperature range | −40 to + 85^{0}C |

Maximum voltage | 1000 V DC |

Operating voltage | 16.8 V |

Components | Symbols | Rating |
---|---|---|

Input voltage | 0 to 120 V | |

Capacitor | 25 uF | |

Inductor | 5 mH | |

Input current | 20 A (Max) | |

Operating frequency | 10 KHZ | |

Output load current | 10 Amps | |

Output power | 1500 W | |

Switches | IRF540 | |

Diodes | MUR1560 | |

Driver circuit | TLP 250 | |

Integral gain | 0.013 | |

Proportional gain | 0.1 |

The simulation results for photo voltaic integrated grid scheme is accomplished in time scale using Simulink that measures performance of converter for a given system. The complete model is obtained from sim-power system tool box. The PV panel voltage and input current waveform is indicated in

The output DC voltage waveform using PI controller is represented in

The output waveform of converter is depicted in

The PWM pulses to the converter switches

The waveforms for grid voltage and current are shown in

The real and reactive power waveform is shown in

The grid current THD with PI and CS-PI is denoted in

The DSPIC30F2010 is cost effective since 8 bit microcontroller is used to develop proposed converter system prototype. The DC link voltage is used by the controller which is linked with DC-DC converter as feedback signal. This maintains converter output as steady state. The potential divider as well as Hall Effect sensor are used to measure real power at grid. The signals are performed by signal conditioners and then fed to microcontroller’s input point. Using inbuilt Analog to Digital Converter (ADC) unit, the signals are digitized.

The input DC voltage and current waveforms are given in

The converter’s output voltage waveform for CS-PI controller is depicted in

The PWM pulses to the converter switches

The grid voltage and current waveforms are denoted in

The comparison of efficiency is depicted in

The comparison of gain is depicted in

The THD comparison is illustrated in

The THD for CS-PI and PI controller is given in

This proposed system examines the dynamics and efficiency of control system against fluctuations that are common in all PV panels due to variation of temperature and intensity. An improved interleaved DC-DC SEPIC converter is employed. It overcomes the drawback of high input current ripples. It also provides excellent buck boost conversion ratio. When compared to other existing converters, the proposed converter consumes lesser components and provides improved energy efficiency. A crow search algorithm is utilized for proposed converter that optimizes the parameters of PI controller. The objective of CSA optimized PI controller of proposed converter is to generate good response and enables working in Continuous Conduction Mode (CCM). The performances improved with this optimization are reduction in ripples, decrease in settling time and minimization of peak overshoots. The obtained converter outputs are applied to a 1Ф VSI which in turn converts the DC input to AC output and supplies it to the gird. After implementing CSA based PI the efficiency of proposed converter obtained is

Photovoltaic

Crow Search Algorithm

Single-ended Primary Inductor-Converter

Proportional Integral

Direct Current

Voltage Source Inverter

Total Harmonic Distortion

Module-integrated converters

inductor-capacitor

Variable Step Size-Least Mean Square

Point of Common Coupling

Solar PV

Unified Power Flow

Current Source Inverter

Gravitational Search Algorithm

Fuzzy Logic Control

Maximum power point tracking

Grey Wolf Optimization

Gradient Descent

Particle Swarm Optimization

Alternating Current

Short Circuit

Open Circuit

Phase Locked Loop

Phase Detector

Loop filter

Voltage Controlled Oscillator

Low Pass Filter

Continuous Conduction Mode

Reference voltage

Actual voltage

Photocurrent

Open circuit voltage

Series resistance

Short circuit current

Shunt resistance

Voltage per temperature coefficient

Temperature

Electron charge

Current per temperature coefficient

Input and output voltage

Peak to peak ripples in inductor currents

Input and output currents

Input inductors of the converter

Output inductors of the converter

Middle capacitors of the converter

Peak to peak ripple of coupling capacitor voltage

Output capacitor

Proportional gain & Integral gain

Amplitude

Angle

Frequency

Phase angle of input signal

Damping ratio