This paper analyses the impact of a firm combined
offer by wind and small hydro generators located in the river
chain, with a view to address the intermittency of wind
generators. Both generations are dispatchable and cleared
against their offer prices. They offer a firm, hourly-schedule (WH
schedule) for 24 hours ahead of real-time operation to an auction
based locational marginal price (LMP) market with other
generators offering to meet the system loads. The model network
consists of other generators and loads at different buses. The
scheduled power is taken off at a predetermined bus, as a load at
the bus. This schedule must be met by the wind and hydro
combined generations. If necessary, a notional thermal
generation is available at a considerable higher price to meet the
schedule, at the off-take point.
The objective is to minimise the total supply cost for 24 hours and
examine LMPs and constraint-on costs while respecting the given
WH schedule, nodal power balance constraint, generation limits,
branch flow and other limits. Discussion is based on New Zealand
(NZ) Electricity Market rules, where generators are self-committed into the into the market. Three scenarios are studied, and the
results presented.