# Review of Power Electronics Technologies in the Integration of Renewable Energy Systems
## 3 Literature Survey  
Renewable energy system technology has become one of the key areas for much of the research and has been treated as the best alternative for the generation of electric power and satisfying the end-user requirements across the globe. The applications of REs have been found to be numerous, and have made researchers focus more on this area to identify more solutions to the many complex engineering problems associated with electric power generation. The integration of REs into grids is still challenging, and enormous research efforts have been made by researchers in this domain, as presented in [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]. The roles of REs in HVDC systems, PLC, SCADA, etc., are also presented here. As stated earlier, grid-connected RESs [10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20] have become vital, although with some constraints. The electricity generated by grid-connected REs, including through the use of grid-connected PV, wind, fuel cells, and wind-hydro plants, is possible only by employing a proper power electronics circuitry [21, 22, 46, 47, 59, 60, 72, 80, 81, 82] in between the source and the load. This circuitry configuration ensures the power transfer and control are achieved in an efficient manner and ensures better reliability at the end. Another critical component in grid-connected RES is the inverter. It plays a vital role in the conversion process. There are many inverter configurations, which have been presented in brief by the authors of [45, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 53, 58, 59, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76]. When connecting a solar PV system to an electric power grid, three types of inverter configurations, namely central inverter, string inverter, and microinverter configurations, have been employed, and an enormous amount of work has been presented by the authors in the references mentioned in this paragraph. A DC-DC converter takes the DC voltage from the REs as the input and provides the DC voltage as the output quantity. It may lessen the voltage or boost the voltage, depending upon the requirement of the end-user and the applications of the proposed configurations, if any. These converters are modelled through various equations. The main component in the converter is the switch, and in order to ensure proper levelling of the voltage, optimum switching is highly necessary. The role and various applications of the DC-DC boost converters have been presented in [23, 24, 54, 55, 56, 62, 63, 64, 77, 78]. Maximum power harnessing is a vital task during the grid integration of REs, as the power generated by the REs is intermittent in nature, and to overcome this difficulty, suitable MPPT control techniques have to be employed. There are several techniques available in the literature, ranging from traditional to soft computing domains. Detailed analyses were presented by the authors of [25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]. The role process. Solar panels generate DC power, and by connecting them directly to the system, we can avoid the losses associated with converting DC power to AC and back again to DC. This makes the overall energy conversion process more efficient. Converters play an essential role in this type of system. DC-DC converters, such as buck, boost, and buck-boost converters, are used to boost or lessen the voltage levels at the output side to ensure optimal power transfer. In addition to DC-DC converters [23; 24; 54; 55; 62; 63; 64; 73; 77; 78], inverters are essential components in power systems connected with DC sources. Inverters [45; 48; 49; 50; 51; 52; 53; 56; 61; 75; 76] convert DC power into alternating current (AC) power, and are commonly seen by all domestic users. They ensure that the electricity generated by solar panels or stored in batteries is compatible with the electrical grid.