Introduction
This dataset records all curtailment events experienced by curtailable-connection customers.
About Curtailment
When a generation customer requests a firm connection
under a congested part of our network, there may be a requirement to reinforce
the network to accommodate the connection. The reinforcement works take time to
complete which increases the lead time to connect for the customer.
Furthermore, the customer may need to contribute to the cost of the
reinforcement works.
UK Power Networks offers curtailable-connections as an alternative
solution for our customers. It allows customers to connect to the distribution
network as soon as possible rather than waiting, and potentially paying,
for network reinforcement. This is possible because under a curtailable
connection, the customer agrees that their access to the network can be
controlled when congestion is high. These fast-tracked curtailable-connections can
transition to firm connections once the reinforcement activity has taken place.
Curtailable connections have enabled faster and cheaper connection of renewable
energy generation to the distribution network owned and operated by UK Power
Networks.
The Distribution System Operator (DSO) team has
developed the Distributed Energy Resource Management System (DERMS) that monitors
curtailable-connection generators as well as associated constraints on the
network. When a constraint reaches a critical threshold, an export access
reduction signal may be sent to generators associated with that constraint so
that the network can be kept safe, secure, and reliable.
This dataset contains a record of curtailment actions
we have taken and the resultant access reduction experienced by our curtailment-connections
customers. Access reduction is calculated as the MW access reduction from
maximum × duration of access reduction in hours (MW×h). The dataset categorises
curtailment actions into 2 categories:
- Constraint-driven curtailment: when a constraint is
breached, we aggregate the access reduction of all customers associated with
that constraint. A constraint breach occurs when the network load exceeds the
safe limit.
- Non-constraint driven curtailment: this covers all
curtailment which is not directly related to a constraint breach on the
network. It includes customer comms failures, non-compliance trips (where the
customer has not complied with a curtailment instruction), planned outages and
unplanned outages
Each row in the dataset details the start and end
times, durations and customer access reduction associated with a curtailment
actions. We also provide the associated grid supply point (GSP) and nominal
voltage to provide greater aggregation capabilities.
By virtue of being able to track curtailment across
our network in granular detail, we have managed to significantly reduce curtailment
of our curtailable-connections customers.
Methodological Approach
- A
Remote Terminal Unit (RTU) is installed at each curtailable-connection site providing
live telemetry data into the DERMS. It measures communications status,
generator output and mode of operation.
- RTUs
are also installed at constraint locations (physical parts of the network,
e.g., transformers, cables which may become overloaded under certain conditions).
These are identified through planning power load studies. These RTUs monitor
current at the constraint and communications status.
- The
DERMS design integrates network topology information. This maps constraints to associated
curtailable connections under different network running conditions, including
the sensitivity of the constraints to each curtailable connection. In general,
a 1MW reduction in generation of a customer will cause <1MW reduction at the
constraint. Each constraint is registered to a GSP.
- DERMS
monitors constraints against the associated breach limit. When a constraint
limit is breached, DERMS calculates the amount of access reduction required
from curtailable connections linked to the constraint to alleviate the breach.
This calculation factors in the real-time level of generation of each customer
and the sensitivity of the constraint to each generator.
- Access
reduction is issued to each curtailable-connection via the RTU until the
constraint limit breach is mitigated.
- Multiple
constraints can apply to a curtailable-connection and constraint breaches can
occur simultaneously.
- Where
multiple constraint breaches act upon a single curtailable-connection, we
apportion the access reduction of that connection to the constraint breaches
depending on the relative magnitude of the breaches.
- Where
customer curtailment occurs without any associated constraint breach, we categorise
the curtailment as non-constraint driven.
- Future
developments will include the reason for non-constraint driven curtailment.
Quality Control Statement
The dataset is derived from data recorded by RTUs
located at customer sites and constraint locations across our network. UKPN’s Ops
Telecoms team monitors and maintains these RTUs to ensure they are providing
accurate customer/network data. An alarms system notifies the team of
communications failures which are attended to by our engineers as quickly as
possible. RTUs can store telemetry data for prolonged periods during
communications outages and then transmit data once communications are
reinstated. These measures ensure we have a continuous stream of accurate data
with minimal gaps. On the rare instances where there are issues with the raw
data received from DERMS, we employ simple data cleaning algorithms such as
forward filling.
RTU measurements of access reduction update on
change or every 30-mins in absence of change. We also minimise postprocessing
of RTU data (e.g. we do not time average data). Using the raw data allows us to
ascertain event start and end times of curtailment actions exactly and accurately
determine access reductions experienced by our customers.
Assurance Statement
The dataset is generated and updated by a script
which is scheduled to run daily. The script was developed by the DSO Data
Science team in conjunction with the DSO Network Access team, the DSO
Operations team and the UKPN Ops Telecoms team to ensure correct interpretation
of the RTU data streams. The underlying script logic has been cross-referenced
with the developers and maintainers of the DERMS scheme to ensure that the data
reflects how DERMS operates.
The outputs of the script were independently
checked by the DSO Network Access team for accuracy of the curtailment event
timings and access reduction prior to first publication on the Open Data Portal
(ODP). The DSO Operations team conduct an ongoing review of the data as it is
updated daily to verify that the operational expectations are reflected in the
data.
The Data Science team have implemented automated
logging which notifies the team of any issues when the script runs. This allows
the Data Science to investigate and debug any errors/warnings as soon as they
happen.
Other
Download dataset information: Metadata (JSON)
Definitions of key terms related to this dataset can be found in the Open Data Portal Glossary: https://ukpowernetworks.opendatasoft.com/pages/glossary/