**8.3 Plug-in hybrid electric vehicles (PHEV)**

RE can be better absorbed if electric vehicle charging and discharging is done strategically. Conventional power supplies can be sent as needed to match demand and provide ancillary services for grid stability. Contribution to grid by RES is increasing although these sources are intermittent by nature. This is now an operational challenge to balance the intermittency of RES. Electric vehicles (EVs) offer a scope to manage demand and potentially mitigate the amount of curtailed energy by controlling when EVs are charged.

Different types of charger such as AC/DC, slow/fast are discussed in European standard by [95]. Integration of ESSs in EVs charging station has grown with AC

*Wind Solar Hybrid Renewable Energy System*

supply energy for 3 h roughly in the evening.

**8. Storage for RES**

during grid connection.

**8.1 The case of grid-level storage**

resource can complement variability of both. As per the policy, a wind-PV plant is defined as a hybrid plant if one satisfies at least 1/4th of the rated power capacity of the other. Different configurations and use of technology for AC, DC integration

The Central Electricity Authority is empowered to frame the standards for connectivity and sharing of transmission lines, etc. for such systems. So in India case study in hardware with grid interaction are limited to academics. A case study of Barwani, [68] found that PV-wind-battery-DG hybrid system is the most optimal solution when cost and emission are the main targets. The work in [69] involves the development of the RE based hybrid system for electricity that can supply desired power continuously throughout the year irrespective of fluctuation of energy available from standalone systems. The energy assessment has been done using Homer simulation tool for developing a small solar-wind hybrid system, at National Institute of Engineering-Centre for Renewable Energy and Sustainable Technologies (NIECREST), Mysuru, India. The WPVHPS was fully charged during the day time and thereafter the performance was checked by connecting to 596 W load through the 1500 kVA inverter and energy meter. The WPVHPS was able to

It should be noted that no ES technology claims high in all aspects. Each has its own limitation in performance when used for grid connection. System capacity, type of application and the cost of peak time electricity decide the storage capacity. A wide variety of such technology may be required to address the issues arising

In [70] an optimized sizing methodology for battery ES to cater peak shaving and ramp rate limiting in the power dispatch using bat algorithm and validated in a grid-connected WPVHPS to combat loss of power is presented. Five types of battery ES such as lead-acid (Pb-acid), Li-ion, flow batteries and sodium sulfur (NaS) are tested in a comparative fashion. After examining storage technologies applied in four purposes such as frequency regulation, power smoothing for wind as base load plant, power smoothing for load following and peak shaving the authors [71] have arrived in a conclusion that the power accumulation capacity is vital for frequency regulation, whereas the energy capacity influences energy intensive applications like peak shaving. The transient stability of a DG-battery-super capacitor has been carried out by [72]. Korada et al. [73] have developed a three-level grid adaptive power management strategy (GA-PMS) in MG with RES—battery-supercapacitor to support grid. A compressed air energy storage (CAES) and wind energy system is used in [74]. It is tried to time shift wind energy to maximize the daily revenue by stochas-

tic dynamic programming (SDP) for forecasting generation and price.

CAES is more viable than the distributed wind turbines-CAES [76].

With similar objective [75] has added an approximate dynamic programming (ADP) algorithm that shows the proficiency of designing near-optimal control policies for a large number of heterogeneous storage devices in a time-dependent environment with good accuracy at par with stochastic and dynamic models when demand-variability is additionally taken. The economic feasibility of a centralized

Koller et al. [77] shows the effect of the grid-connected 1 MW BESS on frequency reserves, peak clipping and islanded operation of a MG. Grid forming and grid following inverters for the variable RES is detailed in [78]. An online

with storage are encouraged with incentives as specified therein.

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but the DC system has higher energy efficiency with improvement up to 10% [96] with less number of conversion stages taking generation from RES. The important communication system, not less than the brain makes it all possible in a coordinated manner. It communicates with the smart metering system present on the MG and on the EV charging station, through Modbus on TCP/IP connection, using the internal LAN, and with the ES converters, through the CAN protocol.

When the market penetration of uncoordinated plug-in electric vehicles (PHEV) is studied by [97], it is encouraged for load control by smart charging. It can reduce the size of central storage devices.

Clement-Nyns et al. [98] have investigated charging and discharging of PHEV in a cooperative manner that helps the voltage control and reduces congestion.

The PHEVs as dynamically configurable dispersed storage can operate in vehicle-to-building (V2B). Based on the distinctive attribute of the battery, the benefits of using PHEVs as energy storage for DSM and outage management are deliberated by Pang et al. [99]. The faster-charging are yet to come up. The parking time can be utilized for charge or discharge mode when required.
