Introduction: FlexNet is a four-year programme focused on seven themes. Of these Intermittency, System Operation and Multi-Terminal High Voltage Direct Current (HVDC) Systems are particular challenges for the UK governments 2020 Low-Carbon Transition Plan (LCTP). The other themes: More Electric Future, Visions and Scenarios, Customer Participation and Active Distribution are topics that prepare for the 2030 onwards agenda.

The uncertainty of the future means that flexibility continues to be an important objective. The programme aims, where possible, to showcase its insights and achievements so that these can be taken up by the commercial sector, government and the regulators for practical implementation.

Objectives: The issues being addressed by the work-streams and reported under each of the themes are as follows:

• Intermittency: The 40% renewable electricity target will be met mainly by wind energy (intermittent generation). This creates challenges for system balancing and security of supply. This research aims to ensure that cost-effective integration of wind generation is achieved.

• System Operation: FlexNets planned research in system operation is proving well-aligned with the recent Electricity Networks Strategy Group and Energy Technologies Institute (ETI) reports. The work is focused on building a modelling and analysis base for testing increased boundary transfer limits and corrective post-fault control. The planning of strategic network investment beyond 2020 is a key topic also currently being pursued.

• Multi-Terminal HVDC Systems: This theme refocuses on power systems electronics in response to the growing development of offshore renewable generation, exploitation of which will require a departure from conventional AC-based transmission. To date, HVDC deployment has been limited to point-to-point connections; realisation of DC networks will require significant research into both control methodologies and underlying hardware.

• More Electric Futures: The dramatic cuts in CO2 in the electricity sector require radical changes. This work investigates these changes and examines the implications for energy networks through 5 projects. The first project addresses the demand placed on the electricity system in GB from the increased use of electricity as the vector for energy transmission and distribution. The second project looks at how significantly increased electricity use should be accommodated within the GB power system. The third project looks at integrated local distribution of gas/heat/electricity.

• Visions and Scenarios: The work done for FlexNet supported the Long-term Electricity Network Scenarios (LENS) project.

• Customer Participation: The emphasis here is on the end use of electricity in an economic, technical and human sense. Work is being undertaken on engaging consumers about the necessary transition towards the 2020 objectives. This is focused on understanding how people view the electricity supply system and their flexibility in interfacing with it.

• Active Distribution: The work examines the distribution planning problem as a stochastic maths programme. Work is also underway on control room interfaces for active networks, and on an active power distribution network and data acquisition simulator/emulator.