Most wholesale electric rate structures include a demand component typically measured over one hour. Frequently the demand is tied to the regional power system's peak hour; this is known as a coincident peak (CP) demand charge. Alternatively, the demand charge applied is tied to the distribution system's one-hour maximum demand; this charge is known as a non-coincident peak (NCP). One way to lower the demand charge is by using Dynamic Voltage Reduction (DVR), which applies conservation voltage reduction (CVR) practices during forecasted peak hours. DVR is a strategy to lower the system operating voltage during the forecast peak window, thus reducing the energy delivered, which results in lower demand. This paper highlights lessons learned during a recent study of four electric cooperatives that utilize this strategy in partnership with their G&T. Additionally, the paper discusses the requirements and best practices for implementation. Finally, the results of a systematic statistical analysis of about 100 distribution feeders are presented. The analysis seeks to identify the load profiles that produced the best results. The information presented provides cooperative engineers with a toolkit and roadmap to evaluate and implement DVR on their home distribution system.
As Electric Vehicle (EV) electric charging demand increases so to does the corresponding load requirements for charging the vehicles. The expansion of power distribution assets is therefore a critical issue to address on whether rural service transformers can handle the increase in EV load demand. Large-scale EV deployment is likely to cause problems in the localized distributions systems bringing challenges such as increased load demand, increased system losses, and additional voltage drops. This paper investigates how rural service transformer resiliency plays an important role in these challenges. EV charging can create new load peaks exceeding the service transformer's rated capacity, thereby accelerating equipment aging. EV charging can also both positively and negatively affect transformer aging. The core purpose of this paper is to investigate that change in service life of rural service transformers.
The power distribution system is becoming more strained as rapidly increasing amounts of generation (e.g., photovoltaics) and load (e.g., electric vehicles) are being connected to the grid. Distribution planners need analytical tools that allow them to decide how to effectively, yet efficiently, integrate those new devices. Hosting Capacity studies are used to estimate the amount of new devices that can be accommodated anywhere on the distribution system without adversely impacting power quality or reliability under existing control configurations and without requiring infrastructure upgrades. Hosting capacity is a complex process that can be divided into three parts: the collection of input data, the analytical engine, and the end-use application of the results. The analytical engine can have different methods based on detailed, streamlined, or hybrid assessments. The detailed assessments are accurate but requires significant engineering and computational effort. The streamlined assessments are fast but not as accurate as detailed methods. Finally, the hybrid assessments aim to have good accuracy while reducing the simulation time. In this paper a hybrid assessment method for performing hosting capacity analysis is presented. The hybrid assessment method proposed considers steady-state overvoltage and thermal ratings. The results of this method are compared with OpenDSS using a model of a real U.S. 12-kV distribution feeder.
The evolving power distribution system, which comprises new technologies such as variable energy resources, changing load patterns and increased monitoring and control, introduces both new opportunities and additional challenges for distribution utilities. Traditionally, planning processes and tools only address a narrow piece of these emerging planning demands. These tools are not equipped to efficiently perform strategic and system-wide studies to support today's integrated resource planning objectives. While current planning tools may have the ability to be used for certain studies within these processes, new capabilities must be developed to comprehensively plan and design a system, factoring in all these complexities efficiently. This paper presents a framework designed for advancing distribution planning by integrating non-wires alternatives. The concepts presented here are applied to a proposed test case for describing the benefits and challenges when using this analysis on a power distribution simulation model.
Distribution utilities know the inherent risks of bypass switching of medium voltage regulators. When bypassing a regulator in any step position other than neutral, dangerous circulating currents can develop due to the voltage across the series winding in parallel with the shorted bypass switch. Conventional distribution protection systems do not adequately protect circulating currents until the regulator, bypass switch, or leads fail and short to ground. This paper Will use case studies to help us understand why the inherent dangers are posed to distribution service personnel and equipment. Though no substation protection schemes are perfect, we will look at the physics of the circuit to determine if some protection schemes are better at protecting field personnel. This would serve to minimize the damage caused when regulators are switched off neutral, and more importantly, enhancing the safety of distribution service personnel while limiting damage to substation equipment.
