Single Phase Smart Grid Tie inverter

Power inverters are devices that can convert electrical energy from DC form into AC form as an output. Inverters can come in many different varieties, with different parameters like price, power rating, efficiency, and applications. The DC/AC power inverter normally takes DC power supplied by a sola

Project Title

Single Phase Smart Grid Tie inverter

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

Power inverters are devices that can convert electrical energy from DC form into AC form as an output. Inverters can come in many different varieties, with different parameters like price, power rating, efficiency, and applications. The DC/AC power inverter normally takes DC power supplied by a solar panel (or) battery, such as a 12-volt battery, and transform it into a 230 volt AC power source operating at 50 Hz, it has emulated the power available at an ordinary household electrical application. Micro solar power systems are designed for the generation of electrical power. They are generally independent of large centralized electric grids and are used in remote areas. By building a grid-tie inverter the household solar power generation systems are connected to the centralized grid system. There is a need to design a low-cost single-phase power inverter that can be used with a small amount of power generation capacity, possibly capable of using small scale solar power generation systems that wish to supply the excess power generated to the electric grid. Operating a renewable energy system in parallel with an electric grid requires a special grid-interactive or Grid-Tie inverter (GTI). The power processing circuits of a GTI are similar to that of a conventional portable DC-AC Converter that operates as a stand-alone device. The main differences are in their control algorithm and safety features. A GTI takes a variable voltage from a DC source, such as a solar panel or battery inverts it to AC synchronized with the mains. It can provide power to our loads and feed an excess of the electricity into the grid. Depending on power and voltage levels, GTIs circuits normally have from one to three stages. When the inverter output is pure sinusoidal and it is connected to the grid. But, to match the frequency, phase, and amplitude of the grid and inverter output. The inverter output depends upon the PWM (Pulse Width Modulation) signals to the gating of the inverter switches. The PWM is generated with the help of the Arduino Atmel 328 controller. Hysteresis current controller is used to adjust the inverter frequency up to the grid frequency. This controller is implemented simply and it provides a good dynamic response and good output current regulation. The project is designed to construct a 200W normal AC Output power and a 250W maximum AC Output power Grid Tie Inverter. The proposed GTI has Over Current Protection, anti-islanding and Reverse Polarity Protection.

Project Objectives

Environmental concerns like global warming and climate change are driving the need for increased penetration of distributed renewable resources into the next generation of the electricity grid. Environmental friendly electricity generation and storage, along with energy policy and regulations are changing the characteristics of electricity networks and supply. As a result, micro grids provide a unique opportunity for integrating renewable resources into the distribution system. Micro grids are small-scale versions of centralized electricity systems where smaller-scale distributed generators and renewable energy resources like wind turbines, solar panels, and energy storage, provide power closer to point of use. As well as providing an opportunity to reduce environmental impacts through increased use of renewable resources, micro grids can improve power quality, network efficiency, reliability, and economics.

The solution this project proposes is an implementation of the designed filter to effectively reduce the harmonics injected into the grid to an acceptable value according to standards and also an approach to control the real and reactive power output of the inverters to help solve the problems of instability and power quality of the distribution system. The design, modeling, and simulation of the smart inverter system are performed in MATLAB/SIMULINK software environment.

Our main objectives are as below;

• To Save extra Electricity and inject it into the National grid station.
• To synchronize the Power generated from Micro independent generating Station with Main Grid i.e WAPDA.
• The output obtained from them is of a square waveform that differs from the waveform of AC current and voltage i.e Sinusoidal.
• The Frequency, voltage, and phase angle maybe not in accordance with the condition of the grid-tie system.

Moreover; Pakistan is moving towards incorporating EVs policies into the automotive industry. So our project can serve as a Vehicle to Grid (V to G) service as well which is the new and trending concept launching in Pakistan.

Project Implementation Method

The design of the hardware & software for GTI consists of the full-bridge inverter, driver circuits, and a low pass filter. The H-bridge consists of IRF530 switches. It has low resistance, less power dissipation, higher efficiency, and fast switching time. It is used to apply the switching pulses coming from the microcontroller to the MOSFET. IR2110 is a high voltage half-bridge gate driver designed to drive both the high side and low side MOSFETs in a synchronous buck configuration. The rising edge of each output can be independently delayed with a programming resistor.

The pulse synchronizing & isolation circuits are used between the microcontroller & MOSFET drivers. The Op-Amps and transistors convert the 2 PWM signals coming from the microcontroller into four signals going to the MOSFET. Optocouplers 6N137 are used to electrically isolate the electronic low voltage circuits from the power electronic section that includes the MOSFETs and drivers that are higher voltage.

The Schmitt Trigger makes a square wave signal from the sine wave that feeds into the timer of the microcontroller. It uses the square wave signal to measure the frequency of the sine wave and determine the zero-crossing times of the sine wave so that the output signal can be generated with the correct phase of the network signal.

B.

PWM signals are produced by the microcontroller which drives the MOSFET; the output from the H-bridge circuit is also a PWM signal that can be produced in different ways. The basic technique is the 2-Level PWM method. A 2-Level PWM signal is obtained from a reference sine wave by modulation with a carrier wave at a much higher frequency. This can be achieved by running both signals through a comparator, which produces an output PWM signal with a duty cycle that is directly proportional to the amplitude of the reference sine wave.

C. Software

The GTI is controlled by the EVK1100, which tracks the phase & frequency of the grid waveform, and

generates output signals to drive the low and high-side of the H-bridge. It is based on a hybrid polling structure. Five functions are executed every cycle through the main loop. A separate function to update the display status is executed when a flag is raised. This occurs less frequently since it does not have a high priority in terms of operating the inverter. The microprocessor runs at a clock speed of 48 MHz. A high clock speed can give a high performance so that the inverter output closely matches that of the grid.

Benefits of the Project

The smart grid is a power production and distribution system that allows for a two-way flow of electricity and communication, ultimately designed to deliver sustainable, cost-effective, and secure electricity supplies. Much like the internet, the smart grid utilizes a range of advanced information, communication, and energy technologies working together to respond digitally to variable electricity demand across the grid. Benefits associated with the smart grid include:

• More efficient transmission and distribution of electricity.
• Quicker restoration of electricity after power outages.
• Increased and efficient integration of variable renewable energy systems.
• This method will also help to save the extra amount of electricity and integrate it into the national grid instead of wasting it.
• The utility grid is a virtual battery
• Net metering (or feed-in tariff schemes in some countries) play an important role in how solar power is incentivized. Without it, residential solar systems would be much less feasible from a financial point of view.
• It can be used for peaking. The networked solar photovoltaic system is the hotspot and focus of the developed countries in the world in the field of photovoltaic applications. It is the mainstream development trend of the world's solar photovoltaic power generation, with huge markets and broad prospects.
• Moreover; Pakistan is moving towards incorporating EVs policies into the automotive industry. So our project can serve as a Vehicle to Grid (V to G) service as well which is the new and trending concept launching in Pakistan.

According to the 17 sustainable development goals (SDGs) set by the United Nations to transform our world, the following are related to our project.

GOAL 7: Affordable and Clean Energy

• Using clean, renewable natural solar energy to generate electricity, does not consume non-renewable, limited resources of carbon-bearing fossil energy, no greenhouse gas and pollutant emissions in use, harmonious with the ecological environment, in line with economic and social sustainability development strategy.

Moreover, our project is also linked with other two goals i.e GOAL 8: Decent Work and Economic Growth & GOAL & 9: Industry, Innovation and Infrastructure.

Technical Details of Final Deliverable

GTI includes two boards, transformers and connections. The board consists of MOSFET switches and drivers, DC regulators, sampling circuits, optocouplers and other devices. Other boards will the Atmel EVK1100 armed with an AVR32 UC3A0512 microcontroller, LCD display and other useful features. The two transformers are used to convert the 230V AC grid voltage to 18V AC and for isolating the electronic board from the 18V AC network voltage. Although the LC filter applied to the output of the H-bridge removes most of the high-frequency noise, a better filter structure maybe needed in the final design.

The frequency, amplitude and phase of the GTI output signal are synchronized with the voltage signal of the grid. The GTI is controlled by an Atmel microcontroller (EVK1100 with UC3A0512). Results confirm that the GTI is capable of producing an AC waveform that is synchronized with the grid. Future software modifications will add the capability to control real and reactive power output from the inverter, in addition to the output frequency.

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Energy

Other Industries

Medical , Agriculture , Manufacturing , Others

Core Technology

Others

Other Technologies

Internet of Things (IoT), Clean Tech

Sustainable Development Goals

Affordable and Clean Energy, Decent Work and Economic Growth, Industry, Innovation and Infrastructure, Climate Action

Required Resources

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