Guide to Connecting a Distributed Generator - Sustainability Victoria

The connection feasibility study (Box 4) will enable you to understand your connection requirements and the status andcapability of the existing network. It will investigate load flows, system and network protection settings, detailed generatordata and costs of network connection. This information may vary between sites.Box 4: Key outcomes of a connection feasibility studyThe key outcomes of the connection feasibility study are identifying:• The electrical characteristics of the generator that influence the connection.• The current fault level status at the point of connection on the network. The general rule for access to connection isthat available fault level headroom (safety margin usually given in kilo-Amperes or kA) at the connection point is largerthan the maximum fault currents that the generator could introduce during its operation.As a minimum, the feasibility study must address the:• Design and physical layout at and adjacent to the connection point• Primary protection and backup protection (DNSP feedback can help)• Operational control characteristics• Communications and alarms• Insulation coordination and lightning protection• Switching and isolation facilities, interlocking arrangements• Metering installationsThe feasibility study should also emphasise the:• Impact on existing customer supply quality• Impact on existing network infrastructure• Fault level issues, including fault clearance times• Stability of the on-site generator• Long-term viability of the generator and operation• Connection to electrically weak networks, if generator in remote location• Transfer of customer load between network and generatorThe study will identify network limitations and inform the development of options for upgrades including voltage control,switchboards, relays, circuit breakers, isolators and fault protection. It should also assist you develop options for yourgenerator’s mode of operation. An island mode of operation, for example, may require additional protection equipment.For systems typically over 1MW capacity, an additional investigation called a network stability study may be required aspart of, or as an extension to, the feasibility study. This may incur additional costs. Check whether this will be required atyour initial meeting with the DNSP.Allow for the cost of these studies in your project budget.Box 5: Key points you can expect your DNSP to considerThat the:• Installation of your proposed generator operates as part of the electrical distribution network• Nature and cost of any extension or augmentation of the existing network deemed necessary and how those costswill be met• Reliability and quality of the grid supply to other customers is not adversely affected by the proposed generator• Safety of other customers, company employees and contractors is not put at risk• Generator is not operated above the agreed megawatt rating• Generator meets approved design and operates reliably.20 - Guide to Connecting a Distributed Generator in Victoria