## 3 Key Contributions to Smart Grids
### Grid Balancing  
Grid balancing represents the energy supplier's task of delivering the right amount of power to the network in a smart grid. Grid balancing has played a vital role recently with cheap, clean energy sources like EVs, wind turbines, and PV panels pouring power into the interconnected power infrastructure [106; 107]. These clean energy sources rely on inherent phenomena, so smart grids are frequently underpowered or overpowered. If these undesirable situations are not properly stabilized, overvoltage can disturb electronic equipment tied to the smart grid [106]. In the absence of energy storage, it is not possible to store electrical energy, but the supply demand values must be equal for smart grids and conventional grids. For this, grid balancing becomes important in smart grids.  
Grid balancing implies that power consumption always corresponds with power grid generation. Since electrical power is inherently difficult to store and must be available when needed, the supply must always be identical to the consumption, in spite of constant fluctuations in both. In an unregulated smart grid, the transmission system operator should provide the grid balance situation. Figure 7 summarizes three different scenarios according to the supply-and-demand situation. This discussion details what happens when the frequency of the system starts to drift away from the desired value (approximately 50 Hertz). The aim of grid balancing is to keep the power demand and supply in balance at all times, especially in the timeframe of seconds to minutes. If the supplied power is less than the demand, the grid frequency becomes less than 50 Hz (Figure 7a). If supplied power is higher than the demand, the grid frequency becomes more than 50 Hz (Figure 7b).  
Frequencies must be kept within legal and operational limits. When the supplied power is equal to that consumed, equilibrium is achieved and the frequency value is equal to 50 Hz (Figure 7c). For grid balancing, grid operators realize positive balancing when the generation is low and consumption is high. In positive balancing, the generating source must produce more energy, or the consumer loads must consume less energy. In negative balancing, this process is conducted in the opposite way of positive balancing.  
The smart grid operators rely on peak shaving and load shifting to avoid high consumption peaks, especially from high-rated consumer loads such as industrial vehicles and EVs. The smart grid has to be built to accommodate the highest demand for power during peak loads. EV loads may fluctuate as a result of the regular operation of multiple industrial companies, like starting or accelerating a production process. Peak shaving is a method for prohibiting peak load values, reducing grid development expenses, and providing saving costs [108]. If the electricity price and grid demand are low, load shifting defines a short-term reduction in electrical energy consumption followed by an increase in generation. If supervised properly, EV integration into the smart grid can greatly help to manage the supply/demand between consumers and producers [109].  
Auxiliary services provide the smooth operation of smart grids. Grid balancing is handled by system operators (transmission system operators, distribution system operators). To supply controlled electrical energy, it is required to keep the frequency, voltage, and power within limited values. This process is achieved through an operating center [110]. A large cyclic generator can be employed for frequency control, but it is a relatively expensive solution. EV energy storage units offer fast charge and discharge rates in smart grid systems, making the power plant an effective option for grid balancing [69].