Control strategies

The Teleport supports a number of local control strategies. Such solutions include but are not limited to:

• Grid power control: adjust power production of solar, wind, and battery assets in order to keep within grid feed-in and/or consumption limits, also in case of fluctuating self-consumption
• Frequency containment control: provide FCR and aFRR services to grid operators

Contact us at support@withthegrid.com if you are interested in a service we do not provide support for yet.

Grid power control

The following grid power control strategies are supported by the Teleport:

• Static production limits
• Peak shaving consumption using batteries
• Static feed-in limit

Static production limits

Each solar and wind asset connected to Teleport can have static production limits configured. This ensures that an asset does not receive a setpoint above or below the configured limits. Each asset can have:

• Upper Limit - Defines a static upper limit on curtailment of an asset. This configuration is useful for locations with limited grid capacity with negligible local consumption. The default upper limit is 100%.
• Lower Limit - Defines a lower limit on curtailment of an asset. This configuration is useful for assets that should not be curtailed to 0% or for locations with a constant base load where part of the generated energy can always be self-consumed locally. The default lower limit is 0%.

Curtailment setpoints through the API can be scaled with respect to the defined limits. The scaling functionality, if enabled, normalizes the setpoint between the defined limit. The impact of the scaling factor on the curtailment setpoint sent to the asset can be seen in the visualization below.

Impact of scaling factor on curtailment setpoint

Peak shaving consumption using batteries

Teleport can provide peak shaving of the consumption by dynamically controlling connected battery energy storage system (BESS).

Requirements

Teleport can talk to a large number of battery and metering assets. It periodically queries the active power at the point of connection (POC), state-of-charge, and the output power of the BESS. By knowing the grid connection capacity, and nominal output power of BESS(es), Teleport can quickly calculate the amount of imbalance and subsequently control the batteries by proportionally charging/discharging the required amount of power.

Teleport peak shaving functionality can be deployed when the situation of the specific use case satisfies the following conditions:

• Teleport asset library supports available BESS(es) and power meter(s).
• The administrative limit for both taking power and feeding power to the grid is known and is below the physical (technical) limit.
• The physical (technical) limit of the protection device (e.g. fuse) is known and is above the administrative limit.
• The nominal output power of the connected BESSes is known.

Static feed-in limit

Dynamic solar and wind control adjusts the power production of solar and wind assets to fluctuating self-consumption in order to keep within the static grid feed-in limit. In combination with an energy meter, Teleport can periodically read out the real-time active power consumed by the load locally as well as the amount of power generated by the installation. As the power fed back to the grid crosses the grid capacity threshold during peak periods, Teleport starts proportionally curtailing any excess power.

Such control allows asset owners to maximize and optimize the use of the available grid capacity. It allows them to dynamically reduce the output power of assets in periods of congestion, therefore, mitigating the imbalance costs incurred during such periods.

Requirements

Teleport can talk to a large number of solar, wind, and metering assets. It periodically queries the active power at the point of connection (POC) and the amount of active power produced by the solar installation. By knowing the peak load and grid connection capacity, Teleport can quickly calculate the amount of access energy and subsequently control the generation by proportionally curtailing the excess power.

Teleport can be deployed when the situation of the specific use case satisfies the following conditions:

• Teleport asset library supports available solar/wind asset(s) and power meter.
• The administrative limit for both taking power and feeding power to the grid is known and is below the physical (technical) limit.
• The physical (technical) limit of the protection device (e.g. fuse) is known and is above the administrative limit.
• The peak load of local uncontrollable consumption is known.
• The nominal output power of the installation is known.

Depending on the desired use case and the values of the above variables our static feed-in limit solution can be deployed.

Control system

Teleport works in a cascade control arrangement (as shown below) where the outer control loop consists of the energy measurement device (e.g. Janitza UMG 806) measuring voltage and current and setting curtailment setpoints of the PV system (e.g. via Sungrow Logger). The inner control loop of the PV system takes care of adjusting the maximum power point.

Our hardware solution satisfies the following requirements:

• Line-to-neutral voltage metering range: 0 - 230 Vrms
• Line-to-line voltage metering range: 0 - 400 Vrms
• Current metering range: up to 4000 A
• Accuracy of the power measurement: margin of error <1% (of the nominal value, class 0.5s)

Closed-loop control diagram

Control

Our API supports the control command for managing configured feed-in and consumption limits of grid power controllers. Specifically, refer to the limitPower command detailed in our API documentation, under limitPower. This command is instrumental in managing emerging services like Capacity Limiting Contracts (CBC), allowing for dynamic adjustment of feed-in and consumption limits for active controllers running on the Teleport. It allows for temporarily reduduction/setting of the feed-in/consumption limits and is relevant for Peak shaving consumption using batteries and Static feed-in limit controllers.

Tip

It is possible to schedule limitPower command together with other scheduling commands (such as setBatteryOperation or limitProductionPower). The grid power control will periodically evaluate the local conditions (considering currently active feed-in/consumption limits) and will restrict the operation of the assets within a safe limit.

Frequency containment control

Frequency containment control is one of the ancillary services provided to transmission system operators (TSO). FCR and aFRR service providers contribute to maintaining system frequency within limits by automatically controlling active power reserves of connected assets based on the frequency deviations and the corresponding droop curve.

Requirements

Teleport can talk to a large number of battery assets. It periodically queries the active power at the point of connection (POC), state-of-charge, and the output power of the battery energy storage system (BESS). Using a single API call, an aggregator can request activation of the FCR mode from the connected Energy Storage System (ESS) through Teleport.

Teleports FCR functionality can be deployed when the situation of the specific use case satisfies the following conditions:

• Teleport supports available BESS(es).
• The BESS is equipped with an FCR module.

Control

The commands available for batteries can be found in our API documentation. Activation of the FCR can be requested by sending a battery operation schedule with deliverFCR.maxRate which represents the maximum dispatch power of the droop curve. The activation of aFRR can be executed by scheduling a direct dispatchPower.activePower setpoint.