Standards Development

Scope

This SRD document describes high-level reference use cases and technical specifications of LVDC systems utilized in public power distribution including stand-alone microgrids in public space. It also gives examples of detailed business and system use cases, as well as properties of the state of art LVDC systems used in public distribution networks and comparable installations today. The specifications are based on an analysis of information collected from industry and stakeholders through surveys.

This document applies to LVDC systems with a nominal system voltage and a rated voltage of equipment not exceeding [up to and including] 1 500 V DC and used in public electricity distribution. High voltage systems and systems used for distribution of electricity in private premises are excluded from the scope. 

For the purposes of this document, Public Power Distribution shall mean power exchange across and beyond the boundaries of private property via a network in a public space, purpose of which is to provide electricity network services to multiple subscribers based on agreements, so that any party can become a subscriber to the service and can be connected to the local network [become grid user].

Note 1: Definition is independent from the physical dimensions, electrotechnical properties and operating modes of the infrastructure. Installations can be very small or large in terms of power and geographical extent and use any voltages and number of voltage levels.

Note 2: Public power distribution can be carried out by a microgrid and it can be completely isolated both from any wider power system and/or common electricity markets (i.e., have its own market or no market at all).

Note 3: Public power distribution is managed by a responsible (often authority licensed) distribution network operator and/or distribution system operator.

Purpose

The ongoing energy transition challenges the existing electricity distribution infrastructure and the conventional network technologies and ways to build and operate distribution networks. The existing infrastructure is aging, and thus, or due to some other reasons, does not meet the modern requirements for transmission capacity, voltage quality, reliability, or economics and energy efficiency.

Today, Low Voltage Direct Current (LVDC) is already used in numerous applications in the elect rical energy system and the number of use cases is expected to continue growing. In recent years LVDC has also found its way into mains distribution in buildings and public distribution networks. LVDC distribution is widely regarded as a potential Smart Grid technology, and a rival to pure-AC distribution, that can cover multiple roles in both conventional power distribution and implementation of local microgrids and facilitate the energy transition. The utilisation of LVDC distribution in public networks is interconnected with several business cases related to power distribution business, electricity markets and energy service provision.

The advantages of contemporary LVDC distribution systems are largely based on the capabilities of modern power electronic converters and their deep integration with ICT systems, in addition to the possibility to increase the power transmission capacity of low-voltage distribution. These include, for instance, advanced measurement, monitoring, and control functionalities, which enable more efficient use of the network capacity. Consequently, LVDC distribution is inherently capable to offer precise controllability and grid management functionalities, implementation of which in pure-AC networks would require additional equipment and effort. The above-mentioned benefits extend beyond the local LVDC networks.

The key preconditions for the large-scale deployment are the achievement of significant economic and technical benefits, compatibility with existing infrastructure, as well as the wide and secure availability of suitable equipment. Distribution System Operators globally have shown great interest towards utilisation of LVDC distribution, and several pilot installations have been constructed. These have proven the technical capabilities as well as the economic potential of LVDC distribution in different applications and established a demand for standardised solutions.

There are many identified gaps in the standardisation relevant to public LVDC distribution today and the existing standardisation is partly confusing, creating uncertainty in terms of the systems and equipment compatibility and the properties and certification of the applicable products. It has been identified that the current state of standardisation hampers the widespread adoption of LVDC systems in public electricity distribution and development of the related markets.

Considering the above-mentioned, there is an urgent need to address the standardisation gaps and develop both horizontal system specifications and vertical product standardisation. Systems -oriented approach based on collection and analysis of the use cases and related system specifications is necessary to ensure the coherence of technical requirements. Well-defined reference use cases and system specifications enable prioritisation of standardisation needs and provide a common basis for the detailed technic al work in the technical committees. Hence, the global market relevance of the proposed SRD is high.

This SRD aims to support the development of relevant technical standards by the IEC TCs. This NP and the SRD builds on the previous PWI stage work of SyC LVDC WG 2 on the collection and articulation of information on use cases and system specifications (e.g., document templates and related surveys). The work is proposed to be carried out by SyC LVDC WG 2.