Issue link: https://fhpublishing.uberflip.com/i/748539
NETWORK / 8 / NOVEMBER 2016 Visibility and control of DER by transmission Extensive Some Limited Visibility and control of DER by distribution Extensive Some Limited Today 1 2 3 4 T he government's long-awaited smart systems consultation is heralded as the vehicle through which the barriers that are obstructing the move towards a smarter energy system will finally be addressed. One of those barriers is the lack of a clear definition of storage – which currently holds a double identity as both generation and demand. But there is still little clarity and consensus on another definition that will arguably be the lynchpin of a future smart system – what exactly is a distribution system operator (DSO) in a UK context? In the rest of Europe, the DSO is the generic term for a company that performs a role equivalent to that of a DNO in the UK, but it does not necessarily mean they are "smart". In the UK this is integral to its meaning. DSOs will have greater visibility and control of assets on their distribution systems, enabling them to get the most from their existing electrical infrastructure by contracting services from distributed energy resources. In this way, they can avoid costly network reinforcement and move away from the traditional redundancy-based model of energy systems. The case for the market role of the DSO is well known. Rapidly increasing numbers of connection requests from renewables developers and other low carbon generation technologies with variable outputs are creating technical challenges for DNOs. There is also expected to be an increase in demand as a result of the electrification of a portion of the UK's heat needs; increased multi-vector interaction between the energy, transport and waste sectors; and a need to allow incentives to emerge to enable customers to save money through active participation. This means DNOs can no longer remain passive when it comes to managing the energy flows on their systems. But opinion is divided over who is best placed to control the system. Should a central independent SO have ultimate control over the entire system? Or would DSOs with enhanced vision over the continually increasing amount of distributed generation attached to their distribution assets be in a better position to balance the system and utilise services such as demand-side response (DSR) and storage? It cannot be both. Flexible methods of connection are being introduced by all UK DNOs, but it is possible that these active network management schemes will contradict actions undertaken by system operators through bilateral agreements. In the absence of guidance from either Ofgem or the government, SP Energy Networks (SPEN) has laid out its intended role in the future market. In its DSO vision, published last month, SPEN weighs up four possible DSO models before opting for the option of most control: total DSO. Through an internal DSO steering group, the network operator has concluded that this model would be the most appropriate one for the UK. Its benefits include meeting local customer service requirements to the fullest, scalable architecture and aligned responsibilities along the asset ownership boundary. The Total DSO model involves the DNOs extending their role to manage all distributed energy resources (DERs) below the transmission/distribution boundary. The DSO would then respond to instructions from the SO and manage the DERs to best meet these instructions. The DSO would also have to facilitate an ancillary services market for DERs. This approach would not be without its challenges. Regulation will be required to standardise the approach among all DSO VISION Key poinTs • SPEN envisions transitioning towards becoming a full DSO to facilitate an open and inclusive balancing services market at the transmission/distribution interface, while also carrying out local system balancing to efficiently utilise the distribution network. • The DSO model will be capable of enacting system balancing actions from the SO within timescales that best meet the needs of the SO and the capabilities of the DERs connected to our network areas. • SPEN's transition to a DSO will be both modular and proportionate. • It will work with key stakeholders to develop and implement a fair and cost effective remuneration mechanism for all DSO services and DER providers. • SPEN will undertake trials in two areas – Dumfries and Galloway and Mid and North Wales will be undertaken to test the DSO model and inform its future form. • Key policy changes will be necessary to allow the remuneration process for DSOs and enable them to procure services for subsequent re-sale. A decision on whether or not DSOs will be able to own and operate storage DER resources is also needed. Dso model options – a high level view 1. Total Tso The existing TSO or independent SO extends its management of DER resources to include all DER assets connected at distribution level, requiring significant extension of capabilities such as system monitoring and control. 2. Dso DeR manager TSO would retain primary control over network balancing services but also contract services from DSOs; such an arrangement is demonstrated by ENW's CLASS project 3. Transmission support Extends the DSO DER manager model with DSOs also carrying out aggregation and management of some DERs 4. Total Dso DNOs extend their role to manage all DER resources below the transmission/ distribution boundary, responding to instructions by the SO and facilitating an ancillary services market for DERs