PowerWorld Corporation | Optimal Power Flow (OPF)

The PowerWorld Optimal Power Flow Analysis Tool (OPF) is an optional add-on to the base Simulator package. Simulator OPF starts with all the functionality of the original Simulator, but then adds an optimal power flow (OPF). Simulator OPF provides the ability to optimally dispatch the generation in an area or group of areas while simultaneously enforcing the transmission line and interface limits. Simulator OPF can then calculate the marginal price to supply electricity to a bus (locational marginal price or LMP), while taking into account transmission system congestion.

The advantages of the Simulator OPF over other commercially available Optimal Power Flow packages include:

Ability to display the OPF results on system one-line diagrams and contour the results for ease of interpretation

Users can export the OPF results to a spreadsheet, a text file, or a PowerWorld AUX file for added functionality

Simulator OPF grew out of a project completed with the U.S. Energy Information Administration (EIA) looking at the cost of supplying electricity in the Northeast portion of the U.S. Because this project involved studying relatively large systems, greater than 9,000 buses, we had to make Simulator OPF fast. As an example, the figures below show contours of several thousand bus marginal costs in the New York and New England regions using FERC 715 data for the power system values and EIA supplied generation costs. Solving the OPF for this 9,270 bus system - including enforcing approximately 20 binding transmission line MVA constraints and calculating the bus marginal prices at 5,627 buses - took about 10 seconds using a 500 MHz Pentium III machine.

Contour of Bus Marginal Prices in New York and New England

Detailed View of Western New York, with Transmission System

V13.0 Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Enhancements

New Add-on Tool (OPF Reserves) to simulate Ancillary Services Reserve Markets.

Generator and Load reserve controls include spinning, regulating, and supplemental reserves.

Area and Zonal constraints include regulating, contingency and operation reserves modeled by demand curves. .

V12.0 Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Enhancements

General Improvements throughout

V11.0 Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Enhancements

V11.0 greatly enhanced the speed of the linear program solution on large power system cases.

Added the ability to dispatch two-terminal DC transmission lines in the OPF and SCOPF algorithms.

Great improvement of the handling of phase-shifting transformers inside the DC optimal power flow. A better coordination of the phase-shifters can improve or help insure convergence.

Great improvement of the dispatch of Area-To-Area MW Transaction Controls to better handle situations where they conflict with one another.

V10.0 Optimal Power Flow (OPF) and Security Constrained OPF (SCOPF) Enhancements

Added support for enforcement of the new nomogram limits in the OPF and SCOPF.

Add load-multipliers that are used when the "Use DC Approximation" option is checked in the Power Flow Solution Options. These multipliers are specified for each bus in the system and are applied to all loads at the bus. These multipliers are intended to represent the transmission system losses that are removed when using the DC approximation.

Add the ability to utilize the loss-sensitivity values which are "User-Specified" in the DC OPF/SCOPF routines. These act as penalty multipliers on the output of power of generators at these buses and will affect the dispatch solution.

Added the ability to specify a piecewise-linear curve to represent the maximum violation cost used in the OPF and SCOPF. This curve can be thought of as a "penalty curve" applied when violating the flow constraints. By specifying lower penalties for lower overloads and then increasing the penalty as the overload worsens, a more gradual change from enforceable to unenforceable will be seen.

Added load dispatch as a control in the SCOPF algorithm.

Added support for modeling reactive flow adjustments in the DC SCOPF algorithm

Added support for calculating the reactive power LMPs when solving the full AC OPF or SCOPF.

Add the MW area-to-area transaction as a control for the OPF and SCOPF algorithms. When the transactions is between two areas that are both on OPF control, then the OPF algorithm will determine the appropriate MW level. If only one area is on OPF control, then a price curve for a MW transaction may be specified to dispatch against.

Added the ability to specify a reference for losses and for energy by Area and Super Area. These references are then used to calculate components of the final MW Marginal Cost (LMP) at each node in a power system. The components are for energy, losses and congestion.

Added the ability to enter "User-Specified" loss sensitivity values at each bus. If the user has loss-sensitivities calculated from an external tool, the sensitivities can be entered into Simulator and Simulator can be instructed to not modify the sensitivities.