Real Time fault detection and classification of a photovoltaic panel system

Solar power is energy from the sun that is converted into thermal or electrical energy. Solar energy is the cleanest and most abundant renewable energy source available. There are three main ways to harness solar energy: photovoltaic, solar heating & cooling, and concentrating solar power. Photo

Project Title

Real Time fault detection and classification of a photovoltaic panel system

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

Solar power is energy from the sun that is converted into thermal or electrical energy. Solar energy is the cleanest and most abundant renewable energy source available. There are three main ways to harness solar energy: photovoltaic, solar heating & cooling, and concentrating solar power. Photovoltaic panels generate electricity directly from sunlight via an electronic process and can be used to power anything from small electronics such as calculators and road signs up to homes and large commercial businesses. Solar energy has come a long way as an environmentally friendly renewable energy source. The history of solar power begins in the 1800s but solar cells have made leaps and bounds in efficiency in the last 30 years. Using solar energy as a main source of electricity is still a work in progress but progress is being made in the solar technology being used. Over the last decade, solar power saw increased acceptance from the general public as a viable energy source to replace fossil fuels. Although PV arrays of such systems are robust, they are not immune to faults. To guarantee reliable power supply, economic returns, and safety of both humans and equipment, highly accurate fault detection, diagnosis, and interruption devices are required. In this paper, an overview of four major PV array faults and their causes are presented. Specifically, short-circuit fault, open-circuit fault, partial shading fault, and degradation fault have been covered. Moreover, a single evaluation metric has been proposed and utilized to evaluate the performances of the PV array. Finally, based on the papers reviewed, PV array fault management future trends and possible recommendations have been outlined.
As the upcoming world is shifting from the conventional non-renewable energy sources to the renewable ones. Our research indicated that solar energy is the most preferred method of energy generation due to its lesser long-term cost, and simple phenomenon. But, as disadvantages come along with advantages this scheme is susceptible to many kinds of faults. The faults include but not limited to, open-circuit, short-circuit, partial shading, degradation, yellowing, micro-crack formation etc. It is very difficult to detect and classify using a non-invasive scheme as a full scheme consists of many panels connected in series to from a string and later on, connected in parallel to form an array giving rise to a fully connected Photovoltaic Panel System. The task is to be performed by measuring the DC output values of the system and comparing them with the fault-free values to detect the type of fault as every fault has a different effect on the output values. Therefore, we intend to develop a system that will be able to detect and classify the type of fault that will replace the need of using non-invasive techniques like visual inspection.

Project Objectives

The goal of this project is to create a low-cost solar panel fault detection system via electronic variables i.e. voltage and current. It can be implemented in fault locators, relays and other protection devices in order to extend its operation.
There are four different types of faults that are going to be detected in this proposed system

• Short-circuit fault; it is basically a line-to-line or line-to-ground fault in which an accidental short-circuit has occurred between two or more lines with different potentials. It can be detected by using the current indicator (by using Isc)
• Open-circuit fault; This fault can be caused by physical breakdown of panel cables or joints, objects falling on the panels, and loose connectors at junction boxes
• Partial Shading fault; It occurs when only a specific part of the array/panel is covered with shade (due to presence of trees, overhead power lines, or nearby buildings) and the rest is exposed to sunlight
• Degradation fault; This fault occurs due to yellowing and browning, delamination, bubbles in the solar module, cracks in cells, defects in antireflective coating and delamination over cells and interconnections

Project Implementation Method

This project uses Electrical current–voltage measurement (EM technique) to detect three different types of faults; short-circuit, open-circuit, and partial shading, and based on these faults it classifies a PV panel and degraded or not. The project begins with sensing the irradiance (by means of a solar cell), temperature, and using these parameters to calculate the open-circuit voltage, and short-circuit current using the initial value of these parameters given at the back of the panel (measured at the standard conditions i.e. 100W/m2 and 25°C).
It is followed by the measurement of output voltage and current.
Then, the theoretical indicators are calculated by dividing the maximum peak value of current and voltage by the open-circuit voltage and short-circuit current respectively.
It is then followed by the calculation of measured indicators, the formula is the same but, maximum peak values of the voltage and current are replaced by the measured values.
It is known that for every fault the voltage and current are affected and every effect is different from each other. Thus, observing the fault behavior on a voltage-current curve (V-I) these conditions are devised and fed into the controller’s algorithm in the form of conditional logic. 
In a nutshell, the current and voltage indicators are calculated using the short circuit current (Isc) and open circuit voltage (Voc) respectively. In order to find the threshold value of the current and/or voltage the indicators are multiplied with the tolerance value. This technique allows for simultaneous detection for different types of faults.
The proposed method is as follows:

When an open circuit fault occurs in one of the PV strings, the output current of the array is equal to the current of the faulty string. The current indicator can be calculated as follows:

RIO = ?RIM

Where,

            ? = 1- 1/Np    Np – Number of PV strings in a PV array

The value of the threshold can be found using the formula:

TIO = ?RIO

When a short circuit fault occurs (in a PV module) in one of the PV strings, the output current of the array is equal to the current of the faulty string. Under these circumstances, the current indicator can be calculated as follows:

RVS = ?RVM

Where,

            ? = 1- 1/Ns    Ns – Number of PV modules in a PV string

The value of the threshold can be found using the formula:

TIO = ?RVS

When a PV array or string is partially shaded it adversely affects the output of the It can be calculated using the values of the maximum peak voltage and current. First, the value of the current indicator is found using the formula:

RIP = Imp/Isc

The value of the threshold can be found using the formula:

TIP = ?RIP

Benefits of the Project

We are making a device that will not only detect faults but also classify them.
Up till now, there have been devices which are used to detect faults manually by analyzing the graphical representation of output voltage & current but there is no such device that not only detects
faults in a photovoltaic system but also classify them.
This system is controlled and monitored by a micro-controller (Arduino MEGA 2560) thus, allowing for simultaneous detection of faults.
The world is facing many challenges in current times, increase in power consumption being one of them. As we know that power consumption has been exponentially increasing annually, different countries have adapted different power generation methods to cater their needs, non-renewable energy being a dominant one. Non-renewable energy may have their advantages but it is not environment friendly and leads to global warming which has been an important concern for the whole world in recent times. Due to this, they have shifted their attention towards renewable energy sources that includes hydro energy, wind energy, solar energy etc. Solar energy has been on the rise since the last decade and is expected to increase even more in the next decade because it is considered as one of the most efficient environment friendly method to generate power. The pace with which solar energy is increasing annually, the need of a device that detects different faults in a photovoltaic system is inevitable. This has motivated us to make a device that will detect different faults in a photovoltaic system.
It has various applications for example, it can be connected with a programmable relay to synchronize them and break the circuit if one of the fault occurs

Technical Details of Final Deliverable

The sytem or final deliverable will include the following components.

1. Current Sensor ACS712

The current sensor is used to measure the current in the circuit that is later used of calculation purposes. When, the current flows through the onboard hall sensor circuit in the IC. The hall effect sensor detects the incoming current through its magnetic field generation. Once detected, the hall effect sensor generates a voltage proportional to its magnetic field that’s then used to measure the amount of current. This is explained in detail in the progress in hardware and software section.

2. Potential Divider Circuit

      This circuit is used to measure the voltage. It consists of a potential divider and the voltage is calculated on the basic principle of voltage distribution. Our current system is based on 4W panels thus ensuring a maximum voltage of 36V. For higher voltages a potential transformer module can be used that can be used to measure a maximum of 300V DC voltage.

3. Solar Cell

      The solar cell is used to calculate the irradiance. The output pin will be fed into the Arduino analog side to calculate the power and later, divided by the surface area of the cell to calculate the irradiance.

4. Temperature Sensor

      The temperature sensor is used to find the temperature of the surrounding as that will help to find the Thermal voltage (Vt­).

5. Keypad

The numpad is used to enter the numerical values that are to be initialized by the user.

6. 16x2 LCD

This is basic LCD that is used to display the messages.

7. Arduino MEGA 2560

The Arduino MEGA is an open-source microcontroller board based on the Microchip ATMEGA2560 microcontroller and developed by Arduino. It is equipped with sets of digital and analog input/output (I/O) pins that may be interfaced to various expansion boards) and other circuits. The board has 54 digital I/O pins, 16 analog I/O pins, and is programmable with the Arduino IDE (Integrated Development Environment), via a type B USB cable. It can be powered by the USB cable or by an external 9-volt battery, though it accepts voltages between 7 and 20 volts.
It will be used to prompt the user to enter the value of parameters, calculate the value of the indicators, and compare them using basic conditional logic to determine the type of fault occurred.
All of the components will be interfaced with the controller.

8. PV Panels

      As explained earlier 6 panels (4W each) are being used for experimentation purposes

Thus, the final deliverable will be a system embedded with the above components except for the 4W solar panels.

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Energy

Other Industries

Core Technology

Others

Other Technologies

Sustainable Development Goals

Affordable and Clean Energy, Responsible Consumption and Production

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com