By Siobhan Day, Content Specialist, Utility magazine
South Australia’s principal electricity Transmission Network Service Provider (TNSP), ElectraNet, recently won Energy Networks Australia’s 2019 Industry Innovation Award for its Dalrymple Battery Energy Storage System (BESS). The remarkable project is now in full commercial operation and is the first BESS in the National Electricity Market (NEM) to provide both regulated network reliability and security services alongside competitive market services.
As one of the most extensive regional transmission systems in Australia, ElectraNet’s network extends across some 200,000 square kilometres.
The transmission network has more than 90 substation sites and 5,500 circuit kilometres of transmission lines operating at 275,000 and 132,000 volts.
The Australian Energy Market Operator’s (AEMO) Integrated System Plan (ISP), published in July 2018, highlighted that energy storage has a significant role to play in the future energy system with the continued growth of intermittent renewable energy sources.
The Dalrymple BESS showcases the widest range of services provided by a grid-connected BESS in the NEM, covering both energy and system security services.
ElectraNet designed, built and owns the Dalrymple BESS and leases commercial operation to AGL. The project received part-funding from the Australian Renewable Energy Agency (ARENA).
Objectives and rationale
The objectives of the project were to demonstrate that utility-scale battery storage can effectively:
- Provide network reliability and security services alongside competitive market services in a network with a high penetration of renewable non- synchronous generation
- Provide “seamless” islanded operation with 100 per cent renewable generation following transmission outages
- Demonstrate a commercial model for the provision of regulated services and competitive energy market services, and build delivery capability for such assets
The Dalrymple 30MW, 8MWh BESS is the first transmission grid-connected battery in the NEM providing both regulated and competitive market services.
The success of the project required significant innovation and leadership, including:
- A first-of-its-kind commercial model to support the provision of regulated reliability and security services by a Network Service Provider (ElectraNet) alongside competitive market services (provided by AGL), challenging perceived limitations to network ownership of battery energy storage technologies
- Navigating the market registration, licensing and connection processes for the first time, paving the way for others to follow
- Largest autonomous regional microgrid development to date co-optimised for both grid-connected and islanded operation, with 100 per cent renewables allowing seamless transition between the two operating modes (for both planned and unplanned islanding)
The Dalrymple BESS also provides pre-emptive emergency response as part of the South Australian System Integrity Protection Scheme (SIPS), providing fast power injection into the network following a significant loss of generation, which helps prevent a major loss of supply to customers.
Rainer Korte, Group Executive: Asset Management at ElectraNet, said that the Dalrymple BESS also includes several other innovative features relative to other generation and energy storage projects.
“Firstly, the inverters have grid-forming capability, as well as the ability to operate at very low short circuit ratios (<1.5), which is significantly beyond what existing grid-forming electronic converter-based generation can perform.
The fast frequency response (synthetic inertia) also has unprecedented response speed (less than 100ms) and bandwidth (frequency droop down to 0.2 per cent),” Mr Korte said.
Additional features include:
- The non-synchronous fault level/system strength has a support capability which runs via short-term fault current overload (>1.0pu rating)
- Islanded grid master control, including wind farm generation MW dispatch/curtailment facilitating supply to the local island indefinitely under reasonable wind conditions Black start capability for the local island with a peak demand of 8MW
- Largest-known indoor and climate-controlled BESS installation (30MW), with the advantages of quicker installation and lower cost compared to containerised battery solutions
- Topology-based Islanding Detection Scheme
- Control system that allows for an external set point, voltage and reactive power regulation or power factor regulation based on control mode priorities
“The BESS can be operating at full capacity and providing meaningful network support within 350ms of a network event being detected about 400km away in the south east of South Australia,” Mr Korte said.
Ensuring reliability and security
The Dalrymple BESS demonstrates utility-scale energy storage as a key enabler of large-scale intermittent renewable energy on an interconnected power system.
“It also demonstrates the application of energy storage to providing essential system security services, such as fast frequency response (FFR), that enable a higher penetration of renewable energy by allowing more conventional synchronous generation to be displaced by renewable generation,” Mr Korte said.
Additionally, the Dalrymple BESS enables the operation of a local islanded system following the loss of transmission supply where demand is supplied by the local wind farm and small-scale solar generation supported by the BESS – with no conventional generation, and regulation services provided by the BESS.
“This will lead to learnings that are applicable at a broader level to a South Australian system with 100 per cent renewable generation, such as the amount of storage that is needed to manage varying levels of demand and intermittent generation,” Mr Korte said.
“More specifically, customers on the Lower Yorke Peninsula are already benefiting from improved reliability with the Dalrymple BESS keeping the lights on during planned and unplanned 132kV transmission line outages.”
ElectraNet conducted a competitive tender process to select Consolidated Power Projects (CPP) as its Engineering Procurement and Construction (EPC) contractor who engaged ABB as power system integration partner.
“With several novel applications, cooperation was required between ElectraNet, AGL, AEMO, CPP and ABB to implement BESS functionality,” Mr Korte said.
“Given that this had never been done before, a key challenge in the execution of the project was determining suitable BESS control parameters for grid-connected as well as islanded operation.
The key to overcoming this challenge was the positive collaborative effort between ElectraNet, CPP and ABB, particularly when optimising these parameters proved more difficult than expected.
“The project had ambitious objectives that targeted a wide range of battery services, including the unprecedented islanding of an 8MW distribution area with the 90MW Wattle Point Wind Farm.
“The collaborative approach taken by all involved in the project was again key to overcoming this challenge, particularly in regards to the regulatory approvals, registration and technical delivery, and achieving seamless islanding with the Wattle Point Wind Farm, which was originally considered as a stretch goal, was hugely satisfying.”
Regulatory arrangements were not well developed to support the connection of the BESS to the NEM with its unique commercial arrangements, but by working with market and regulatory authorities, including AEMO and the Australian Energy Regulator (AER), ElectraNet was able to develop regulatory solutions to support the project.
A multitude of benefits
In its first six months of operation, the Dalrymple BESS experienced several planned and unplanned transmission network outages, which required the BESS to supply the local 33kV distribution system to successfully maintain customer supply for up to seven hours.
In addition, the BESS successfully rode through network fault events with its measured voltage, active power and reactive power response in line with design and technical performance expectations.
The BESS responds almost instantly to the system voltage depression during a fault and injects a significant amount of active and reactive power into the network to support network voltage recovery.
Customers are benefiting from the Dalrymple BESS operation through improved reliability and security, and the provision of competitive market services.
The project is also helping support the transition to smart grids, with the Dalrymple BESS’ fast frequency response functionality now a standard requirement for new BESS grid connections.
With the Dalrymple BESS being one of the first to be registered in the NEM, it has also assisted AEMO in developing registration procedures for utility-scale battery technology.
The project has incorporated a knowledge sharing portal, which provides a significant amount of information to assist the entire utility industry in observing first-hand how the Dalrymple BESS is performing.
The knowledge sharing portal can be accessed via www.escri-sa.com.au.
The project is also being closely observed by AEMO to gain insights into how a BESS can effectively provide system security services.
The experience gained from this will assist to determine when a BESS can be relied upon to provide such services, potentially leading to less reliance on synchronous generation to provide system security services in the NEM.