This is part four of our six-part DERMS series. If you missed the previous part, it can be found here:
Part 4: Essential features and requirements
The many faces of DERMS
Typically, the requirement for DERMS is driven by the need to accommodate new distributed generation (DG) onto existing distribution networks without passing on expensive network reinforcements to customers that would act as a commercial barrier. However, the forecast uptake in the electrification of transport (particularly electric vehicle charging) and the electrification of heat in some countries (i.e., the transition from gas boilers to electric heat pumps) may see the need to manage demand in some distribution networks. The potential for distributed energy storage systems (DESS), particularly the forecast uptake of battery energy storage systems (BESS) to assist in the management of demand and generation, adds to the potential distributed energy resources (DER) to be managed.*
*DESS can provide other ancillary service support to system operators such as fast frequency control.
DERMS addresses the need to control the access of demand or generation customers connected to the distribution networks. It is especially beneficial at times and at specific locations where the distribution network assets could otherwise experience stress, either thermal or voltage-related. At such times, a DERMS would control the level of generation power export or demand import (or possibly both) to avoid local network stress.
A DERMS can take many forms, depending on the goal. An example might be a localized active network management (ANM) scheme where DG associated with a single primary distribution substation is directly controlled to limit export when needed to avoid stress at the primary substation. Alternatively, a DERMS might be a commercial arrangement with demand customers to limit demand at certain times. A centralized DERMS as part of a distribution system control room could potentially cover a distribution system operator’s full distribution network, controlling demand, storage and DG.
Figure: The many faces of DERMS
Key requirements for a DERMS
Regardless of the application, there are some key requirements for a DERMS. These include:
- Visibility of the network to identify operational margins available
- The ability to enroll DER in available programs for operational controls
- The ability to forecast likely operational margin issues
- The ability to forecast DER capacity that can be utilized for control purposes
- The ability to operate in a hybrid environment of distributed and centralized intelligence
- The ability to make decisions and send out optimized control instructions to controllable DER
- Commercial arrangements to compensate DER for the provision of services (e.g., contractual terms or market trading arrangements)
- Accurate measurement and verification, settlement and record keeping of DER participation in network control
- Ability to store historical data and perform data analytics to optimize DERMS performance
- Secure protection against cyber risks and the provision of safe network operations and secure supplies to customers
DERMS as part of a greater ecosystem
In terms of network operational visibility, smart meters are predicted to have an important role to play by providing power and voltage measurement at the low-voltage network extremities. Technical control systems and commercial systems are required to operate together in real time to ensure network limits are adhered to at the optimum commercial rate and considering the challenges presented by unplanned network outages (outages due to faults or extreme weather).
The adoption of SCADA-based advanced distribution management systems (ADMS) to improve network availability and operational safety can support the provision of a centralized DSO control room DERMS. A typical ADMS will be supported by a live system network model that can carry out load flow and fault level modeling to support power and voltage control functions; fault location, isolation and system restoration (FLISR); and advanced feeder reconfiguration (AFR), etc. In terms of DER management, the control algorithms not only have to consider the DER real and reactive power but also other automated controls on the distribution network such as transformer tap changers, line voltage regulators and compensating capacitors. Controlling the network power flows within the network limits can therefore be complex and a combined ADMS and DERMS system with advanced algorithms may have advantages over a non-model-based DERMS solution. Potentially, a SCADA-based ADMS/DERMS would also require grid edge communications and sensing to extend the visibility of the network, possibly supported by predictive analytics to substitute for missing sensor or model data. Advanced data analytics, artificial intelligence and machine learning can be applied to forecast network capacity and DER capacity to assist in supporting the DSO. There are a few SCADA-based ADMS/DERMS products on the market today, with ABB Ability™ Network Manager providing an advanced offering to DSOs.
It should be noted that as DER management becomes a relied-upon non-wires alternative to traditional network reinforcement, network planners will require new tools and sources of data to develop reliable solutions. A model-based ADMS/DERMS solution and associated historical data repository with data analytics can be an enabler for this.
In part five of our six-part series, we will discuss DERMS for transmission and distribution operators.