Paralleling GXPs

Parallel connections can impact the achievement of the System Operator's Principal Performance Objectives, the grid owner's Asset Owners Performance Obligations, and the operation of protection systems.

Transpower as both the grid owner and the System Operator, in conjunction with distributors, needs to assess the impact of parallel connections to identify risks, and plan to mitigate these as required. The Electricity Industry Participation Code sets a number of requirements that are to be met by asset owners relating to paralleling Grid Exit Points.

Asset owners must apply to the System Operator to parallel Grid Exit Points (GXPs) at least eight weeks before the paralleling is planned to occur. This allows enough time for the grid owner and System Operator to assess the application. Approved applications are valid for two years.

We also need to be notified the day before paralleling is planned to occur. This allows time to confirm that the parallel connection will not be adversely affected by the expected system conditions, such as planned outages and scheduled generation.

In real-time, the distributor will then co-ordinate the parallel switching through the National Grid Operating Centre (NGOC). Before agreement to proceed is given, the proposed paralleling will need to adhere to any conditions given in the grid owner/distributor agreement as detailed in the register of agreements.

We are presently reviewing our interim documentation on this process. While this is underway please contact Grant Tuffery at Transpower (phone 04 590 7000) regarding any application for paralleling GXPs