The rapid growth of industries and load consumption increases the energy demand that needs to fulfilling this energy demand can be obtained from various alternative sources has much importance. The novel hybrid renewable energy system consists of different sources such as the Photovoltaic (PV) system, Wind Energy system (PMSG), Fuel Cell, and the AC source are implemented as energy sources.
The battery and Super Capacitor are used to store excess energy from all sources together which are connected to the DC microgrid. Therefore, the grid provides good quality of power to two different loads namely 48V DC output and 110V AC single-phase output. In this proposed system many individualized converters are used in the DC bus to deliver appropriate power in it. The DC microgrid simulated in the MATLAB Simulink, the observations and results authenticate that the power generation sources enhance the stability of power, reliability, and power efficiency in the microgrid.
In recent years all know how rapidly industries are growing and load consumption is increasing because of that the energy demand was increases day by day. In the early 20th century AC power stations and transmission lines would be placed more throughout the countries to the generation of a large number of AC power grids, with the quick adoption of AC power supplies, DC power grids were left behind. However, the recent power grids failure across the country, communities, and government looking for a more reliable, efficient, and sustainable solution for power needs, DC microgrid has been a solution of unresisted power supply. A microgrid is a local energy grid with control capability consisting of interconnected loads and distributed generators, which means it can disconnect from the traditional power grid and operate autonomously.
Microgrid does not define with their size associated to the power consumption, but the U.S. Department of Energy defines them as systems consisting of less than 10MVA which is the standards of load. These DC Microgrids consist of hybrid renewable energy systems consists different sources such as Photovoltaic (PV) system, Wind Energy system (PMSG), Fuel Cell, and the AC source are implemented as energy sources. The battery and Super Capacitor are used to store excess energy from all sources together which are connected to the microgrid . To isolate the system from a larger utility microgrid having an interconnection switch that is used to operate upstream of the grid. The operating voltage of microgrid is depend upon their applications and it must have control capabilities, protection, and monitoring system of all units.
The renewable energy sources and storing units has able to carry a partial load or full load within acceptable and frequency variations. The microgrid consists of a DC sub-system that is used to cover smaller areas, such as a small industry or single building, which may operate at low 120V voltage levels. While the other side a system covering a larger area of several miles can operate at 12kV – 70kV voltage levels commonly seen in sub-transmission and distribution systems . Renewable energy sources like wind turbines (PMSG), Photovoltaics (PV) are majorly used in the design of microgrids. If the larger grid fails, a microgrid can provide backup power with the help of a diesel generator to a single building, for a small-town generating power getting from the renewable energy sources and distribute throughout [3-4].
Combining renewable energy sources is an important feature because it is decreasing the capital cost required to changeover a system into a microgrid design. Usage microgrid and hybrid renewable energy sources can be utilized and the overall cost of consumers electric bills will be decreased. The hybrid renewable sources self-generated DC power supply with the help of individual convertors and fid to a grid for fulfilling energy demand, sometimes that system-generated excessive power then it will be stored in storing units like battery and super capacitor, etc., also it can supply to the main grid when total production exceeds consumption, the excess power generated is sold back to the main grid.
Using DC microgrids the power generation is localized and minimum energy losses from transmission lines by around 6% decreasing average emissions to produce energy. Additionally, the DC microgrids can Fargo some AC/DC or DC/AC conversions which cause around a 10% efficiency loss because the sources are natively DC producing . Therefore, the system can be economical as well environmentally friendly.
II. CONFIGURATION OF DC MICROGRID
A DC microgrid system uses the different renewable sources that are generating the power required by the load. The system has comprised the following elements.
110V DC bus which integrates renewable sources, converters, storage components with the local loads.
The wind energy system consists of 1kW PMSG, which has a gearless wind rotor and generator, because of that it does not require frequent maintenance.
PV module which is made up of semiconductor device (i.e. silicon) with boost converter based on the requirement.
200V Battery and Super Capacitor are integrated into the DC grid via a buck-boost converter.
48V DC load and Varying Single-phase load integrated to the DC grid through Inverter.
By using the DBR (Diode bridge rectifier) the single-phase 230V with 50Hz output voltage of the AC grid is converted to ripple DC. The rippled DC gets converted into the constant DC with the help of a buck inductor, which is fed to the DC grid from the ZETA converter where all the other modules are connected. We have two loads on the load side, one is a 48V DC load and another is a 110V 50Hz AC load integrated through the inverter. The inverter works on the simple sinusoidal PWM technique converting DC to 110V 50Hz AC output. The 48V DC load is connected to a DC-DC buck-boost converter with a switching frequency of 20 kHz and the 0.1 duty ratio [4-5].
In this paper, a hybrid renewable energy based microgrid system is developed, analysed, and investigated. In that, we study the behaviour of the grid connected hybrid system with two different loads are connected to them. Using zeta converter ripples are less in DC link, improved power factor 0.8 -0.96, and reducing harmonics in the voltage waveform. This system utilizes an alternating off-grid power transmission system with economic parameters. Various techniques and modeling of storage devices were presented. The simulation result shows that the system has desirable, can maintain better quality power, cost efficient to the customers and utilities easily in all domains.
A. Conflict of Interest Statement
Authors declare that they do not have any conflict of interest.