Using electrification and automation
elements support faster and more effective responses to power disturbances and enable balancing and securing the grid, especially during peak demand periods and with variable RE availability. Smart grid technologies also support the coordination and integration of microgrids with the distribution system and BPS. Conversely, a microgrid is designed to accommodate electrification technologies like RE sources, BESS, and EVs. Microgrids and smart grids require automated controls, including a distributed energy resource management (DERM) system.
non-dispatchable and not directly controllable by the utility. The centralized, automated control enabled by smart grid technology is needed to compensate for the fact that the RE sources used for electrification and EV charging are not as predictable as conventional utility grid elements. Smart grid and microgrid controllers need information from various sensors to monitor connected resources in real time. With the advent of EVs and EVSE, the controllers are also used to help manage power demands of charging, and they can use vehicle- to-grid (V2G) communication to coordinate the connection of EVs to the grid or a microgrid to provide incremental energy storage capacity.
In addition to monitoring the status of connected resources, controllers for grid-connected microgrids must also monitor the status of the local utility grid. Switchgear is an essential component of smart grids and microgrids and must respond in milliseconds to ensure robust operation. Switchgear sizes vary from a few kilowatts (kW) for small microgrids to multiple Megawatts (MW) for large microgrids and the utility grid. The switchgear and controller can be in the same cabinet for small microgrids, reducing costs and speeding installation. Smart grid and microgrid DERMs include intelligent metering of energy production and energy consumption that is used by cloud- based analytics to maximize the
Figure 1: DERs exist in the distribution system (blue); other renewable energy resources are in the bulk power system (green). (Image source: NERC)
Smart grids, microgrids, and electrification A microgrid is a DER, but not all DERs are microgrids. From the perspective of the BPS, the terms microgrid and DER refer to types of power generation or storage resources. The term smart grid refers to the communication and control technologies used by the BPS to ensure resilient and efficient operation. Another differentiating factor is that microgrids include generating and storage resources plus loads. A smart grid is comprised primarily of generation resources, with some storage but no loads. The smart grid can communicate with loads, but they are separate from the grid. Electrification affects microgrids, the BPS, and smart grids in
different ways. In the BPS, electrification is being added to an existing grid and, if not properly managed, can have
distances, connecting large-scale bulk electricity generation facilities with interconnection resources and substations (Figure 1). DERs are any non-bulk system resource, including generation units like wind turbines and photovoltaic installations, energy storage units, most battery energy storage systems (BESS), EV battery chargers — also called electric vehicle service equipment (EVSE)— and microgrids. DERs exist behind the utility meter as well as directly on the distribution system. Behind the meter, DER sources include photovoltaic arrays, BESS, grid-connected EVs, and standby backup power sources like large diesel generator installations at data centers and other locations. A microgrid is a particular type of DER.
DERMs are a must
DERMs and automation are defined and implemented differently in smart grids and microgrids. Smart grids include diverse generation sources and electricity users spread over a wide area with a centralized control center for grid management (Figure 2). Grid management is the key concept for smart grid control in the BPS. Existing BPSs were designed and built before there was a need to support electrification, and they can experience unreliable operation as dispatchable (controllable) fossil-fuel-powered generation is increasingly replaced by unpredictable (and therefore less controllable) RE sources. In addition, charging large numbers of EVs will be mostly
unintended negative operational consequences. That’s where smart grid technology comes in. Two-way communications and control are the primary differentiator of smart grids. Those control systems include sensors to monitor the stability of the grid and advanced meters to monitor electricity demand. They also use a variety of controllable power switching and power quality devices to manage electricity flows. The sensors are critical to enable greater penetration of renewable energy (RE) sources and electrification into the BPS and ensure grid stability. In addition, the sensors and control
Figure 2: A smart grid relies on automated controllers and DERMs for real-time grid management. (Image source: ETAP)
we get technical
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