The Technical Rules define a small power station as one or more generating units at a particular location that are to be connected to Western Power’s distribution network. The aggregate rated capacity of the station must be greater than 30 kVA but not exceed 10 MW, and be such that the generating units are not subject to dispatch by System Management in accordance with Market Rules.
In addition to the installation and protection requirements specified in the Technical Rules clause 18.104.22.168(g) states that – “All small power stations must provide earth fault protection for earth faults on the distribution system. All small power stations connected at high voltage must have a sensitive earth fault protection scheme.”
This requirement does not apply to the connection of energy systems rated at and up to 30 kVA, connected to the Western Power’s distribution low voltage (LV) network via inverters, in respect of which Technical Rules clause 3.7 applies.
Customers when upgrading their existing or designing a new high voltage (HV) supply arrangement, need to take into consideration, the functionality of their connection in terms of both current, future load and generation expectations. Where the intent is to connect generation infrastructure to Western Power’s distribution network, it is a mandatory requirement to provide earth fault protection.
To achieve this, the customer is required to provide appropriate current and voltage transformers in association with suitable isolation devices at a customer’s point of supply. Access to Western Power’s metering equipment to facilitate activation of the customer’s protection device is not available and as such cannot be used to meet customer generation protection responsibilities.
Clarification of Technical Rules customer obligations has been deemed necessary given the rapid growth in generation connections and requests to access network equipment which cannot be provided due to a range of network complexities and constraints.
As previously stated, existing customers looking to add generation capacity larger than 30 kVA, will need to include the required generation protection equipment within their own HV installation.
Connection equipment modifications may also trigger the need to upgrade the existing site and supply arrangement up to a point where it is compliant with current standards and practices. Should this be the case, Western Power would encourage customers and property owners to initiate an early conversation on their needs and expectations to ensure that the required outcome can be achieved within realistic parameters.