Power System Operations
SYSTEM OPERATING PROCEDURES
Under the National Electricity Rules NEMMCO has dual roles as market operation and system operator for the National Electricity Market. NEMMCO's highest priority as power system operator is the management of power system security and reliability. Security of supply is a measure of the power system's capacity to continue operating within defined technical limits even in the event of the disconnection of a major power system element such as an interconnector or large generator. Reliability is a measure of the power system's capacity to continue to supply sufficient power to satisfy customer demand, allowing for the loss of generation capacity.
NEMMCO's system operating procedures are developed primarily for NEMMCO operations staff to provide information related to the management of the NEM and security of the power system.
NEMMCO conducts the market through a centrally-coordinated dispatch process that pools generation from producers and delivers required quantities of electricity from the pool to wholesale consumers. Specific activities in achieving this include managing the bidding, scheduling and dispatch of generators, determining the spot price, measuring electricity use and financially settling the market.
Dispatch related documentation includes:
Ancillary services are those services used by NEMMCO to manage the power system safely, securely and reliably. These services maintain key technical characteristics of the system, including standards for frequency, voltage, network loading and system restart processes.
NEMMCO operates 8 separate markets for the delivery of frequency control ancillary services (FCAS) and purchases network control ancillary services (NCAS) under agreements with service providers.
FCAS providers submit bids in a similar way to generators bidding into the energy market. Payments for ancillary services include payments for availability and for the delivery of the services.
Ancillary services documentation includes:
NETWORK RATINGS & OUTAGES
The Network Outage Schedule (NOS) lists the planned network outages for work on the transmission system. Specialist staff within NEMMCO assess the outage bookings and the forecast demands for the period and provide feedback to the TNSPs on the likelihood of each outage proceeding. Bookings may be made up to two years in advance or at short notice in response to an emergency. The schedule contains all out of service work, and any secondary bookings that are forecast to cause a constraint on the dispatch process.
POWER SYSTEM PERFORMANCE MONITORING
NEMMCO is responsible under the National Electricity Rules for ensuring that the power system is operated in a safe, secure and reliable manner. In order to fulfil this obligation, NEMMCO controls key technical characteristics of the system, such as frequency and voltage, to within specified limits.
NEMMCO is in the process of developing a number of tools to monitor the performance of these key technical characteristics. It is intended to use these tools to produce and publish reports on a regular basis.
The first group of these tools has now been developed allowing frequency and time deviation performance to be assessed against the requirements of the Reliability Panel’s frequency operating standards. It is intended to provide monthly performance reports based on this assessment.
An additional tool has been produced permitting NEM wide Frequency Control Ancillary Service (FCAS) performance to be assessed for individual frequency events. This information is also included in the monthly report.
For further information regarding performance monitoring please contact: Ramitha Wettimuny, System Operations Planning and Performance.
For previous months data please contact the NEMMCO Information Centre with the details of the data you require.
Frequency and Time Deviation Monitoring in the NEM
