# Dynamic Voltage Optimization Based on In-Band Sensors and Machine Learning
## 2 CVR Background  
CVR is a closed-loop optimization of power offered versus power required. The process of maintaining the voltage supplied to loads on the distribution grid while minimizing the total power required for system operation has been described by many terms, including CVR, LDC, VSR, and DVO. Here, we use the generic form \"CVR\" or \"DVO\" to discuss legacy implementations and related approaches, and the modified form \(\overline{\text{DVO}}\) to describe enhanced approaches. The elegance of a functional CVR implementation lies in the simplicity of Ohm's Law: Reducing the voltage supplied reduces the power consumed. In contemporary CVR implementations, the difficulty lies in \"closing the loop\" between loads consuming power and the substations supplying power to the distribution grid. To provide operational boundaries on this process, most utilities and regulators follow ANSI C84.1 [18], which dictates that the AC voltage delivered to each customer must be 120 VRMS +/ -5%, or 114 to 126 VRMS. From the service provider's perspective, an effective CVR implementation allows the reduction of power input without degrading service levels to customers, and provides a controllable approach to contemporary issues such as peak-shaving. From the customer's perspective, an effective CVR implementation is completely transparent because power delivery is uninterrupted, and peak-shaving is implemented in a fair and dynamic fashion. Thus, a \"good\" CVR implementation reduces the cost of providing power, which is a benefit to the service provider, while maintaining service levels, which does not perturb or disrupt customer requirements. Many references describe this as \"bottom half\" (114-120 V) versus \"top half\" (120-126 V) performance. In the absence of CVR, utilities typically practice a form of \"oversupply\" or \"top half\" performance to ensure that the voltage provided to loads is higher than the lowest allowable voltage. To evaluate the operational impact of an effective CVR implementation, two complementary perspectives or \"use cases\" must be considered. The first use-case involves the activation of CVR as a system-wide conservation mechanism. The second use-case involves the activation of CVR as a method for Demand Response (DR), or peak shaving with rapid response times. The primary difference between these two use-cases is the segment of time where the CVR implementation is \"active\". In the case of conservation, the CVR implementation is constantly active and adjusting the Actual Supplied Voltage (ASV) to achieve dynamic reduction in system losses. In the case of peak shaving, the CVR implementation is only activated at times when the peak demand is experienced, and CVR is used to reduce power for short periods of time. When CVR is employed as a system-wide conservation mechanism, the service provider dynamically manages all ASV values to a point just above the minimum acceptable level, or Minimum Supply Voltage (MSV), resulting in overall power reduction. The calculations are simple and can be expressed as a net savings in energy and a resulting benefit in generation capacity, or  
\[\%\Delta E=\text{CVR}_{f}\times\%\Delta V \tag{1}\]  
where \(\%\Delta E\) is the percentage of total energy savings, expressed as a function of the CVR factor (\(\text{CVR}_{f}\)) and the percentage reduction in supply voltage (\(\%\Delta V\)) [25]. When CVR is employed as a peak-shaving mechanism, it is only active when the service provider is experiencing peak demand. In this case, CVR is used to reduce power for a short period of time in order to maintain system stability. This use of CVR as a peak-shaving mechanism is effective due to the presence thermostatically controlled loads such as electric dryers, water heaters, and electric baseboard heaters.