Alan Louis

Principal Engineer Technology Innovation, Energy Queensland

Protection Challenges in the Design and Operation of LV Microgrid Systems

Over 10 years experience in the distribution supply industry and a technical lead in the research and development of new technologies for modern supply of power systems. Currently the Principal Engineer in the New Technology group within Energy Queensland. Experience relates to the integration of distributed energy resources (DER) in the distribution network and isolated networks, in particular around power converter interfaces and lithium-ion based energy storage systems. Examples of recent experiences/projects includes, technical lead in the compliance assessment of a number of solar farm connections in QLD, which includes dynamic stability assessment in PSCAD and Powerfactory modelling packages. Technical lead in the control and operation of the static-var-compensators (SVCs) within Energy Queensland’s network, including stability impacts from nearby solar farm connections. Lead engineer for the 83kVA/200kWh lithium-ion storage system, which is a development platform for advanced control systems for distribution network and isolated network applications. Heavily involved in the control system design and implementation of the Grid Utility Support System (GUSS) which are 20 x 25kVA/100kWh lithium-ion systems deployed across regional Queensland to support the SWER network, in lieu of traditional augmentation.

Abstract Outline:

The uptake of distributed energy resources (DER) consisting of power converter interface with battery energy storage presents opportunities for microgrids that are capable of intentional islanding from the grid. There are significant challenges for the protection of an electrical system during islanded operation, in terms of safety and reliability. This is primarily due to the relatively low short-circuit contribution from power converters compared with the grid, and the relevance of this to the wiring rules and the design of the protection scheme. This is significant due to the potential penetration of battery energy storage systems (BESS) with islanding/backup capabilities in residential, commercial and utility applications.

This presentation covers Energy Queensland’s experience in the implementation of commercial-scale microgrid via battery energy storage systems, which includes experience from the 150kW solar PV and 250kVA/250kWh BESS at Eagle Farm, Brisbane and the 83kVA/200kWh BESS at Spence St Depot, Cairns. Both BESS consist of lithium-ion technology coupled to the grid via a power converter interface.

The experience is focussed on the protection scheme in LV applications and includes:
– Discussion of challenges with microgrid operation and impact on the existing electrical installation, of which BESS is a retrofit
– Design of the protection scheme for the microgrid and considerations with the wiring rules and other relevant standards
– Consideration of microgrid applications at a MV and HV level and the protection implications