Cloud seeding occurs between April and November each year during the normal rainy season. In 2006/07 there were 70 flights, 29 of which conducted cloud seeding.
A study of the socio-economic impacts of cloud seeding was instigated during 2006/07 following repeated criticism from the West Coast Council, concerned about adverse impacts of cloud seeding-induced rainfall on residents and businesses in the municipality. The scope of the study was finalised in the reporting period with input from the Council to ensure its concerns will be included. The study is to be conducted independently of Hydro Tasmania and is expected to be completed by the end of 2007.
The efficiency of dispatching energy is influenced by system constraints, ancillary services requirements, available bidding tools and the efficiency of outage planning.
Since NEM entry, Hydro Tasmania has been in ongoing negotiations with NEMMCO and Transend Networks to ensure system constraints are set to allow maximum flexibility while retaining system security requirements. Progress towards a better balance between the needs of generation and system security is providing positive outcomes. Constraint conditions will be subject to ongoing negotiations as we learn more about the nature and impact of constraints on market operations.
The supply of ancillary services during this period of low water supply was costly for Hydro Tasmania.
Work towards improving the situation in the 2006/07 period included negotiations with NEMMCO about ancillary service requirements and introducing an automated application to adjust the capability of our plant to provide services at varying water levels. Hydro Tasmania has also commissioned additional capability in frequency control ancillary services (FCAS) to lift the level of this service.
We will review our systems and procedures to improve flexibility and assist in maximising value, taking into account the lessons learnt in our first full year.
A new outage management system (eGO) was implemented in May 2007. It aims to improve the efficiency of planning and implementing outages, both forced and planned.
Our plant was reviewed against NEMMCO’s revised Generator Performance Standards, a major undertaking given the total number of generator units in Hydro Tasmania’s 28 operating power stations. The standards were accepted and a compliance plan agreed. There was good cooperation on the revised standards between NEMMCO, the National Generators Forum, the Australian Energy Market Commission and Hydro Tasmania. Hydro Tasmania continues to enjoy a good working relationship with NEMMCO.
Table 4 Key performance indicators
Equivalent forced outage factor: The percentage of time outages have occurred that are not planned or for maintenance
and cannot be delayed by 48 hours
Performance remains stable on these indicators despite the increase in start/stop of machines by approximately 60 per cent since Basslink began operation.
Network service providers
Generator upgrade connection applications have been processed by Transend promptly and without issue.
Where connection assets maintained by Transend are for the sole use of Hydro Tasmania, differences remain regarding priorities on asset upgrade programs.
The challenge remains to deal with these upgrades in a way that meets the needs of both organisations.
Under the current drought conditions, Basslink is playing an important role in ensuring the Tasmanian electricity demand is met. Without Basslink, Hydro Tasmania estimates that hydro storages would have been around six per cent lower than they are currently. At such levels the supply would be jeopardised and it is highly likely some form of power restrictions would have been experienced during the 2007 winter.
A net export of 400 GWh was forecast for the reporting period with expected normal rain patterns. However, the extreme low inflow into storages through the year resulted in a net import of 1360 GWh. Basslink flow was made up of 1980 GWh of import and 620 GWh of exports.
The performance of Basslink during the initial period of commercial operation from 28 April 2006 was monitored by an independent Project Inspector. On 5 March 2007, the Inspector certified that Basslink operations and performance met contractual benchmarks.
With the completion of construction and proving stages of the Basslink Project, Basslink Pty Ltd is being sold by its parent company, National Grid plc, as the retention of its Australian asset is no longer a fit with National Grid’s wider strategic direction. Hydro Tasmania and National Grid have worked together closely to ensure this process satisfies the requirements of both parties. Hydro Tasmania looks forward to building a productive long-term relationship with the new owner of Basslink Pty Ltd.