vSPD
The Authority developed vSPD to facilitate more detailed analysis of existing and potential future market-related issues.
vSPD is developed in GAMS and is based on the published SPD formulation. This includes the standard LP formulation as well as the integer formulation to resolve circulating branch flows, non-physical losses on the HVDC branches and branch limit redefinition for the mixed constraint formulation.
vSPD takes advantage of the computational efficiency of commercial Locational Pricing (LP) solvers through vectorisation of the schedule solves. This vectorisation involves reformulating the sequential trading period problems as a single optimisation problem, requiring just a single LP solve for the entire schedule. As an example, a final pricing solve which normally solves 48 half-hour trading periods sequentially, can be vectorised into a single simultaneous solve. This reduces the model solve time in GAMS.
The data inputs for vSPD are in made available in GDX (GAMS data exchange) format. This is an efficient binary format that is readable by GAMS programs. vSPD GDX files may be downloaded from the Electricity Authority's market data and reporting portal.
vSPD currently produces the following outputs in CSV and GDX formats:
- Summary: includes objective function value, total generation, total load, total losses, total violations, total reserve requirements, total rentals
- Offer: includes energy, FIR and SIR provided by market offer
- Node: includes generation, load and price by market node
- Bus: includes generation, load and price by network bus
- Branch: includes connectivity, flow, loss, terminal bus prices, shadow price and rentals by branch; and
- Reserve: includes required reserve, reserve price and reserve violation by island and reserve class (e.g. fast IR and sustained IR).
vSPD results have been successfully benchmarked against those from SPD under different scenarios.
The vSPD model can be downloaded from http://code.google.com/p/vspd/downloads/list.