# Effective Management System for Solar PV Using Real-Time Data with Hybrid Energy Storage System
## 1 Introduction  
Installations of solar photovoltaic (PV) and wind are steadily increasing due to exhaustion of fossil fuels, its price variation, instability in trading of coal/crude oil, and issues of greenhouse gases [1]. Utilizing more renewable energy sources (RES) minimizes the dependency on imported fossil fuels and creates sustainable energy production. However, RES is highly intermittent and fluctuating in nature. Particularly, the PV system is highly reliant on climatic or geometrical conditions and output power severely oscillates during bad climatic situations. The higher fluctuations in the injected power will seriously affect the power system stability. Hence, the energy storage system (ESS) is an essential element to mitigate these variations and improves the system power quality [2, 3]. Generally, the ESSs are a battery, super-capacitor (SC), flywheel, and superconducting magnetic energy storage (SMES), etc. The battery is a continuous power application device and usage is popularly increasing worldwide. The need for high power and energy demand can be achieved by combining battery and SC devices called as HESS and it is interfaced with a DC link employing bidirectional converters, which allows power into and from the ESS devices [4, 5]. The importance of these ESSs can perform a significant role in the context of microgrid (\(\upmu\)G) systems. Generally, the group of sources associated together to form a uG such as distributed energy sources, storage systems, and loads. uGs are categorized as DC, AC, and hybrid uGs. The hybrid uG is the combination of AC and DC uG. The DC uG is more preferred over the AC uG. It has various benefits such as better efficacy, less control complexity, and low power loss due to fewer conversion stages [6]. The benefit of a DC power system is the lack of reactive power over an AC power system. Reactive power leads to a loss of power in the lines, over-size of the inverters and the DC bus capacitors, and decrease in the line power transmissions' ability that affects AC power systems' efficiency and their reliability. Nevertheless, only active power in the lines is transmitted in DC uGs that reduce the sizing of wire and DC bus capacitors. The DC uGs are thus more efficient and reliable than AC uGs. In the meantime, it will reduce costs further by eliminating the power conversion stages for complete converter sources and variable-speed drives. Harmonic nonlinear load currents increase energy loss in lines, transformers, and converters, thus reducing transformers and converters efficiency in AC uGs. In addition, nonlinear loads affect the control system and, in some cases, also cause instability. Due to the high permeability of nonlinear loads in power distribution systems, DC uGs are again preferred to AC uG from the point of view of performance, reliability, and stability. The regulation of DC uGs is very simple compared to AC uGs as the power is regulated by the DC bus voltage and the angular and frequency stability control complexity does not show up in DC uGs. Thus, DC uG appears to be efficient, reliable, and economical [7]. The uGs are performed in two modes such as grid-connected and stand-alone mode. In stand-alone mode, the power balance is achieved by the ESS. During grid-connected operation, the grid can provide the balance power as the number of sources is correlated to sufficient demand of the load [8]. A typical DC uG is shown in Figure 1. In this, the RESs and ESSs are linked to the DC bus through interfacing converters. The ESSs in this system can be used to limit the PV power variations as well as maintain power stability. These converters work in parallel and there is a necessity to sustain the power balance at the DC link [9]. The instantaneous power balance is obtained from the following equation,  
\[p_{in}(t)=p_{dc}(t)+p_{out}(t) \tag{1}\]  
where, \(p_{in}(t)=p_{res}(t)+p_{ess}(t)\) and \(p_{out}(t)=p_{dc}(t)\), \(p_{res}(t)\) is the power from RES, \(p_{dc}(t)\) power absorbed by the DC link capacitor, and \(p_{ess}(t)\) is the power from ESS.