Royal Children's Hospital Co-generation

Green energy compliance is one of the 'big issues' for developers and project proponents. One way that a building's energy rating can be improved in Victoria is by installing gas reciprocating co-generation. The idea is that one unit of electricity produced from gas produces less C02 than an unit of electricity produced by brown coal, which dominates electricity production in Victoria. By installing a gas co-generation plant to supply a portion of the building's electricity demand, some of a building's CO2 emissions may be offset. Also, it is possible to capture some of the waste heat from the gas engines and use it for building heating and cooling.

DIgSILENT Pacific was engaged by Norman Disney and Young (NDY), to complete the stability analysis of the co-generation plant for the Royal Children's Hospital in the Melbourne CBD. The building includes two 1.42 MVA gas engine generators. These units run in parallel with the Citipower distribution system.

An increase in fault level is a common issue with co-generation. This is because the distribution system was not designed for distributed generation and the equipment can be several decades old. Provision of series reactors to limit fault current contribution is often a practical solution to this problem.

Other aspects of the Royal Children's Hospital connection study included:

• investigation of voltage variation at the point of common coupling due to the generation;
• recommendation of protection systems for the generator and building; and
• fault ride through of the generation for faults within the distribution system;

DIgSILENT Pacific has expertise in co-generation stability and grid connection studies. For more information contact us at our Melbourne or Perth offices.