Table: Advanced DER Functions and their Potential Grid Benefits
Table 1— Examples of Advanced DER Functions and their Potential Benefits to Grid Planning and Operations
# |
Advanced DER Function |
Grid Benefit |
Brief Description of DER Function |
Purposes or Scenarios for the DER Function |
Information Requirements |
Planning Issues related to DER Scenarios |
Operations Issues related to DER Scenarios |
1 |
Anti-Islanding: Support anti-islanding in cases of unintentional islanding |
Public and Personnel Safety Equipment Preservation Reliability and Power Quality Improvement |
DER rides through temporary voltage and frequency anomalies, but disconnects when ride-through limits are exceeded, or other signals indicate an unintentional islanded situation. There may be passive autonomous functions; active autonomous functions; and EPS activated functions. |
DER trip only when voltage or frequency limits are exceeded over specified time periods as opposed to immediately, thus remaining connected for as long as possible yet disconnecting to avoid safety or damage problems |
Autonomous: execution |
Anti-islanding protection schemes should be tested for different sizes, locations, and environments of DER units |
Anti-islanding disconnections should be validated as having occurred as required |
2 |
L/HVRT: Provide ride-through of low/high voltage excursions beyond normal limits within preset voltage-time limits |
Reliability Improvement |
DER rides through temporary voltage anomalies, ceases to energize if necessary, and starts/continues to energize immediately if voltage recovers within the clearing time, but disconnects if ride-through voltage-time limits are exceeded |
Fewer service interruptions will occur since the DER systems can stay connected, possibly cease to export power on lower voltage dips, but nonetheless continue or start to export power again if the voltage levels have recovered within normal limits within the time frames. |
Autonomous: execution |
L/HVRT limits need to be studied, provided to the DER, and validated for different scenarios |
Correct operation of ride-through situations should be validated |
3 |
L/HFRT: Provide ride-through of low/high frequency excursions beyond normal limits within preset frequency-time limits |
Reliability Improvement |
DER rides through temporary frequency anomalies, ceases to energize if necessary, and starts/continues to energize immediately if frequency recovers within the clearing time, but disconnects if ride-through frequency-time limits are exceeded |
Fewer service interruptions will occur since the DER systems can stay connected, possibly cease to export power on higher and lower frequency excursions, but nonetheless continue or start to export power again if the frequency levels have recovered within normal limits within the time frames limits. |
Autonomous: execution |
L/HFRT limits need to be studied, provided to the DER, and validated for different scenarios |
Correct operation of ride-through situations should be validated |
4 |
Frequency-Watt: Counteract frequency excursions beyond normal limits by decreasing or increasing real power |
Reliability Improvement
|
DER decreases real power output during high frequency situations, including during L/HFRT events. DER increases real power (it if is able to do so) during low frequency situations. |
Upon high frequency events including during a L/HFRT event, the DER “ceases to energize” so that no real power is exported even though the DER remains connected to the EPS. Hysteresis can be used as the frequency returns to within the normal range to avoid abrupt changes by aggregations of DER. DER increases real power (it if is able to do so) during low frequency situations. |
Autonomous: execution |
The frequency scenarios are studied to determine the most appropriate reductions in real power for different situations. |
DER responses to frequency events are monitored for use in determining updated settings |
5 |
Dynamic Current Support: Counteract abnormal high or low voltage excursions by providing dynamic reactive current support |
Reliability Improvement Power Quality Improvement |
DER provides dynamically adjusted reactive current support during voltage deviations. These dynamic support actions are based on a combination of the rate of change of the voltage levels and the duration of the abnormal voltage dips or spikes. |
Dynamic reactive current support during abnormal voltage conditions counteracts the voltage spikes or dips, with the goal of minimizing these and returning the voltage within normal limits. |
Autonomous: execution |
An assessment identifies those DER units or locations for DER units where reactive current meaningfully impacts EPS voltage excursions. The dynamic reactive current settings are studied to determine the most appropriate for different DER locations, sizes, aggregations, and other considerations |
After-the-fact DER information on the use and possible impact of the dynamic reactive current settings is collected. |
6 |
Soft-Start Reconnection: Reconnect autonomously after grid power is restored |
Reliability Improvement Power Quality Improvement |
DER waits a pre-established time until both voltage and frequency are within normal limits, and then either ramps up upon reconnection at a pre-established ramp rate or waits a random time within a pre-established time window to start energizing. The Area EPS could delay this reconnection (see Command DER to Delay Connection) |
By either requiring DER systems to ramp up during reconnection or to reconnect randomly within a time window, the sharp transitions and consequential power quality problems of voltage spikes, harmonics, and oscillations can be avoided, including the possibility that the disruptions caused by the reconnection of large numbers of DER systems actually precipitates another power outage. |
Autonomous: execution |
Reconnection wait times, ramp rates, and time windows need to be studied and established for different DER locations, sizes, aggregations, and other considerations |
Correct operation of DER units should be validated |
7 |
Command DER to Connect or Disconnect or Delay Connection: Perform soft or hard connect or disconnect from grid via direct command |
Reliability Improvement |
DER system performs a disconnect or reconnect on command from a facility energy management system or from the utility management system |
The connect command is sent to the DER in order to offset local load, to provide post-contingency load shift headroom, or to provide sufficient aggregate capacity to address a circuit overload condition. The disconnect command is sent to the DER in order to avoid reverse power flow or other emergency situation. |
Remote: DER units receive connect or disconnect commands from utility, REP, or FDEMS |
DER is placed within the EPS at a location where output change is shown to mitigate an identified overload or other emergency condition. This requires an assessment of Area EPS to determine locations with elevated reliability risk due to loading of individual components |
Monitoring of the DER status and local circuit conditions provide the necessary information for determining whether a connect or disconnect command is necessary. |
8 |
Backup: Provide backup power after disconnecting from grid |
Reliability Improvement |
DER units automatically provide power to a local EPS for backup if the facility disconnects from the Area EPS. The load is pre-selected to remain energized and the DER generation is adjusted dynamically to balance that load. |
DER units are installed to provide real and reactive power at the site without offsite power |
Autonomous: execution |
DER units are placed within the local EPS at a location with direct access to the pre-selected load |
DER units provide temporary backup power to the facility upon loss of Area EPS power |
9 |
Support Creation and Operation of Islanded Microgrid: Disconnect from the Area EPS while establishing a pre-designed microgrid |
Reliability Improvement |
A DER microgrid management system creates a microgrid to minimize the extent and length of power outages. The type and aggregated capabilities of the DER units within the microgrid are capable of balancing the expected loads on a sustained basis. The DER units support microgrid operations according to the settings provided by the DER microgrid management system. |
DER units enter microgrid mode upon separation from the Area EPS, acting either as leading or following the microgrid frequency and voltage, some of them (or none) acting as base and other (or all) as load-following generation, as established by the microgrid management system capable of matching microgrid loads |
Autonomous: execution |
DER units are pre-configured to be capable of operating in a microgrid |
DER units are switched into microgrid mode by the DER microgrid management system and dynamically match generation to loads on a sustained basis |
10 |
Decrease Export of Real Power at PCC: Response to command/ requests either to increase import or to decrease export of real power |
Reliability Improvement |
DER responds to a command from a facility energy management system, retail energy provider, or utility to decrease the export of power at the PCC. This can be achieved by decreasing generation, increasing the charging of storage units, or increasing local load. |
A circuit is not capable of handling the exported power from the DER and is becoming overloaded. Decreasing the DER exported power reduces this overload. |
Autonomous: execution once decrease command is received |
An assessment identifies those DER units placed at locations where excessive generation can overload the circuit. Those DER units are required to be capable of limiting export power. |
Area EPS circuits are monitored for possible generation overload conditions and, if detected, DER units are commanded to decrease the export of power at the PCC. |
11 |
Limit Maximum Real Power: Limit maximum real power output at the ECP or PCC to a preset value |
Reliability Improvement |
DER exports power at the PCC up to the maximum limit. When near this maximum limit, the DER can remain within the limit by decreasing generation, increasing the charging of storage units, or increasing local load. |
The maximum export limit is established to avoid overloading a distribution circuit and otherwise-required capital project. This autonomousaction means that the Area EPS circuits do not need to be monitored in real time for possible circuit overloads due to excess generation. However, this approach may be not be optimal since actual circuit conditions may not match conditions in the assessments. |
Autonomous: execution once limit is established |
An assessment identifies those DER units placed at locations where excessive generation can overload the circuit. Those DER units are required to be capable of limiting export power. |
Adjust real power output to the limit commanded by the utility, REP, or FDEMS |
12 |
Increase Export of Real Power at PCC: Response to command/ requests either to decrease import or to increase export of real power |
Reliability Improvement Transmission Operational Support Congestion Reduction Efficiency |
DER responds to a command from a facility energy management system, retail energy provider, or utility to increase the export of power at the PCC. This can be achieved by increasing generation, increasing the discharging of storage units, or decreasing local load. |
The increased export of DER power at the PCC expands otherwise-constrained post-contingency load shift or backup connection opportunities. |
Autonomous: execution once increase command is received |
An assessment is made of Area EPS locations with elevated reliability risk due to limited post-contingency load shift or backup connection opportunities. The DER within appropriate locations are contracted to respond to commands to increase exported power at the PCC, thus providing additional “headroom”. |
The Area EPS is monitored for its risk level of post-contingency requirements to shift load. DER units that are capable of providing beneficial additional export power are commanded to do so. |
13 |
Set Real Power: Set actual real power output at the ECP or PCC either as a specific real power setpoint or as a percentage of local load |
Reliability Improvement Transmission Operational Support Congestion Reduction Efficiency |
DER responds to a command from a facility energy management system, retail energy provider, or utility to set the export of power at the PCC. The command can either be a specific real power setpoint or a percentage of local load. This can be achieved by modifying generation, modifying the charging of storage units, or modifying local load. |
A base or known generation level is established for DER or its facility without the need for constant monitoring. |
Autonomous: execution once setpoint is provided |
An assessment identifies those locations where excessive generation from DER can overload the circuit. Those DER units are required to be capable of setting export power. |
DER receives command to set real power |
14 |
Follow Schedule of Real Power: Follow schedule of actual or maximum real power output at specific times |
Reliability Improvement Transmission Support Congestion Reduction |
DER units are scheduled to export real power (or a maximum of real power) for different times of the day, week, or other time frame. DER validates and follows the schedules at the appropriate times |
DER generation and storage is scheduled to take into account the expected load, the net cost of self-generation, the net cost of Area EPS power, and additional market criteria, with the purpose of managing load |
Autonomous: execution once the schedules are received and validated |
DER generation and storage schedules are developed to optimize expected power system conditions, including market signals |
DER units operate according to their schedules |
15 |
Follow Schedule for Storage: Set or schedule the storage of energy for later delivery, indicating time to start charging, charging rate and/or “charge-by” time |
Reliability Improvement Transmission Support Congestion Reduction |
The utility, facility EMS, or DER unit establishes and executes storage charging and discharging schedules for time period ranging from minutes to hours to days or more. “Charge-by” times permit flexibility in exactly when charging is executed, so long as it is completed by the specified time. DER validates and follows the schedules at the appropriate times |
The DER storage schedules are designed to perform peak shaving and/or to mitigate a possible circuit overload or over-generation at specific times. |
Autonomous: execution once the schedules are received and validated |
DER storage schedules are developed to optimize expected power system conditions, including market signals |
DER storage schedules are monitored to ensure they are providing the expected load management results |
16 |
Volt-Var Control: Execute volt-var control in response to settings that define reactive power output for different voltages |
Power Quality Improvement Efficiency/ CVR |
DER monitors local voltage and modifies either available vars (vars that do not impact real power output) or total vars to counteract changes in increases and decreases of voltage within the normal range. Deadbands may be used to minimize unnecessary fluctuations of var changes, and hysteresis may be used to avoid hunting as voltages shift |
In coordination with load tap changers, capacitor banks, and voltage regulators, DER units can counteract voltage increases or decreases to help stabilize voltage levels on circuits and help maintain them within the normal limits. DER volt/var responses can also help maintain CVR voltage levels. |
Autonomous: execution, |
DER volt/var settings are studied to determine the most effective for different types, locations, sizes, and aggregations of DER on different types of circuits, including at different times of day or week. These volt/var settings need to be coordinated with other distribution equipment settings. This requires a detailed assessment of Area EPS voltage conditions. |
The real-time results are monitored of the coordinated settings of DER and other distribution equipment to establish adequate if not optimal settings for most scenarios. |
17 |
Operate by Fixed Power Factor: Provide reactive power by a fixed power factor |
Power Quality Improvement |
DER provides a fixed power factor |
DER helps to compensate for different types of loads and better maintain feeder voltage at nominal without actively changing vars. However cannot actively respond to voltage changes |
Autonomous: execution |
The most appropriate fixed power factor for the DER is established through studies of the impact of power system equipment and loads on its circuit. |
DER power factor is reviewed periodically to determine if the setting is still the most appropriate. |
18 |
Define Use Ramp Rates: Use the different ramp-up and ramp-down rates that have been defined for normal, emergency, and reconnection |
Power Quality Improvement |
DER real power ramp-up and ramp-down rates are established for normal, emergency, and reconnection scenarios. Additional ramp rates may be established for schedules, vars and other transitions. |
Ramping DER real power output helps avoid sharp transitions and the consequential power quality problems of voltage spikes or dips, harmonics, and oscillations. |
Autonomous: execution |
Ramp rates are studied to determine the most effective for different types, locations, sizes, and aggregations of DER on different types of circuits, while still not impacting the benefit of exporting as much real power as possible. |
The real-time impacts of ramping are monitored to establish compliance and better understanding of those impacts |
19 |
Voltage Smoothing: Modify real power output in response to local voltage variations |
Power Quality Improvement |
DER modifies its real power output to counteract voltage variations while voltage still remains within normal limits |
DER counteracts voltage variations through changes in real power for the purpose of remaining within CVR limits or minimizing voltage fluctuations due to impacts from nearby loads or other DER. This function may be used if reactive power is not feasible or may be used in conjunction with volt-var control |
Autonomous: execution |
DER voltage watt settings are studied to determine the most effective for different types, locations, sizes, and aggregations of DER on different types of circuits, while still not impacting the benefit of exporting or importing as much real power as possible. |
The results from DER voltage smoothing actions are collected and analyzed to better understand the impacts of the actions and possibly modify the settings |
20 |
Frequency Smoothing: Smooth minor frequency deviations by rapidly modifying real power output to counteract these deviations |
Power Quality Improvement Bulk Generation Support |
DER modifies its real power output to counteract frequency variations while frequency still remains within normal limits |
DER counteracts frequency variations through rapid changes in real power for the purpose of minimizing frequency fluctuations that can be more costly for bulk generators to counter. |
Autonomous: execution |
Studies can be made to determine optimal settings for modifying real-power in response to different types of frequency variations |
The results from DER frequency smoothing actions are collected and analyzed to better understand the impacts of the actions and possibly modify the settings |
21 |
AGC: Support frequency regulation by direct automatic generation control (AGC) commands |
Ancillary Services Bulk Generation Support |
DER modifies its real power output in response to AGC commands |
DER provides frequency support as an ancillary service to utility automatic generation control. The most effective would be for large aggregations of DER to provide this ancillary service, such as virtual power plants, actual power plants, or large EV charging stations. |
Remote: Receive AGC commands to modify real power output |
Studies determine how much AGC support could be provided by specific aggregations of DER under different scenarios |
AGC control commands are issued every few seconds to the DER units |
22 |
Operational Reserves: Provide “spinning” or operational reserve by increasing real power from generation or storage as bid into market and upon command |
Ancillary Services Bulk Generation Support |
Upon command, the DER provides the incremental energy capacity which has been bid into the energy market. |
DER provides operational energy either immediately or within a contracted longer term. DER that can increase real power upon command, such as energy storage units, can participate. Aggregations of DER such as DER power plants are most likely to be effective. DER can support bulk generation which may not be able to respond as quickly |
Remote: Increase real power output command to contractual level from utility, REP, or FDEMS |
DER is assessed to determine if operational reserves are possible and will not negatively impact local circuits and equipment. |
Command to increase real power to the contractual level is issued. Monitoring determines if DER is providing the contractual real power |
23 |
Black Start Capability: Provide black start capabilities upon command |
Ancillary Services |
Upon command, the DER participates in initiating recovery from outages within an EPS that has no external source of energy. |
DER which is capable of starting without offsite power is used to provide energy to a local EPS which can eventually be connected to other local EPS to eventually join the Area EPS. Black start DER can minimize the time that a local EPS is without power. |
Remote: Black start mode command from utility, REP, or FDEMS |
DER is assessed to determine if it can provide black start capabilities within it local EPS, and whether that EPS can eventually be interconnected with other EPSs. |
Command to start exporting real power is issued. Monitoring determines if the DER is providing the contractual real power. Local EPS is eventually connected with other EPSs. |
24 |
Emission-constrained Dispatch : Set output real power on command, based on emissions produced |
Emission Reduction |
Utility, REP, or FDEMS selects which DER units are to generate how much energy in order to meet emission constraints, and issues appropriate commands to these DER units |
DER units are emission-constrained so that their use is limited and should be managed. Using DRs within their emission constraints benefits the overall emission reduction goals. |
Autonomous: execution |
DER is assessed to determine the types and amount of emissions it creates and are ranked from these assessments |
DER output information is collected to determine the amount of emission reductions it contributed |
25 |
Support Situational Awareness: Provide real-time or near-real-time DER information |
Enables or enhances other benefits |
DER provides alarms and supporting alarms, actual status, DER output measurements, local power system measurements, and other real-time and near-real-time data |
DER real-time or near-real-time information provides (possibly aggregated) data to the utility, REP, and/or FDEMS in order to support real-time and short-term analysis applications. |
Remote: provide DER information to utility, REP, and/or FDEMS |
Real-time or near-real-time information requirements from DER are assessed to determine which data should be used as input to which energy management applications |
DER real-time or near-real-time information is monitored, collected, aggregated, and assessed for validity |
26 |
DER Registration: Provide operational characteristics at initial interconnection and upon changes |
Enables or enhances other benefits |
DER nameplate information and other characteristics are provided to the utility, REP, and/or FDEMS |
DER operational characteristics provides base information for use in energy management applications |
Offline or Remote (may be prior to installation): Provide DER operational characteristics to utility, REP, or FDEMS |
DER operational characteristics are assessed to determine which data should be used as input to which energy management applications |
DER operational characteristics may be collected to determine if there are any changes. |