Model predictive control for converters in hybrid AC/DC microgrid part II

• Main Author: Loh, Zheng Yang
• Other Authors: Wang Peng
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: http://hdl.handle.net/10356/78195
• Institution: Nanyang Technological University

As countries develop and grow their economies, one inevitable effect it has on earth is the hasten global warming due to the increase in energy demand. The largest contributor to the emission of greenhouse gases which causes global warming is the power stations which burn coal and natural gas in exchange for electrical energy. Although it is possible to remove greenhouse gases directly from power station using flue gas, it is often not preferred due to its high cost as well as lengthy and difficult process. Climate changes caused by global warming will not only have disastrous effects on many industries of a country but also the safety and well-being of the people living near the coastal regions. There are many legislative implementations in attempt to reduce greenhouse gas emissions. These implementation boils down to 4 core concepts. They are • Limiting carbon emissions of all plants generating electricity through resources which are not replenishable; • Encouraging renewable energy technologies which do not contribute to carbon emissions; • Reducing energy losses in all generating plants; • Encourage electricity consumers to be more prudent in their usage. However, these legislative implementations have their limitation. In order to truly reduce carbon emissions, renewable energy technologies have to be enhanced till they are capable of taking over electricity production by power plants. In the recent years, Renewable energy systems have quickly gained popularity across the world. Contributing up to 19% of the world’s energy consumption in 2010 and still growing, renewable energy systems prove to be a promising alternative over coal and natural gas. Having an astounding growth of 30% per year, photovoltaic industry is clearly the leader in renewable energy technologies. In order to integrate these renewable energy technologies into the current power system, the usage of microgrids is necessary. The figure below represents a typical set-up in a microgrid. Microgrids have the ability to control many distributed energy resources (DERs) safely and systematically while they are connected to the utility grid as seen in the figure above. Besides maximizing the use of the clean energy resources, microgrids also can operate in islanding mode should grid failures and fault occur. Renewable energy system integration into power systems connected to the grid have proved to be difficult because of the challenges it comes with. The most significant challenge is the fluctuation in the output voltage and power. As a result, renewable technologies are heavily dependent on power electronics to control its output voltage and power. Susceptible to failure, power electronics are not as reliable as traditional devices and can cause a significant and substantial downtime of these three-phase grid connected inverters as well as maintenance costs should they fail to work. Power electronics are prone to failure as its lifetime is highly dependent on the thermal stress exerted on it.