# Power Systems Analysis Software

### From Open Electrical

Power systems analysis and simulation software are ubiquitous in electrical engineering practice. Initially, they were used to quickly solve the non-linear load flow problem and calculate short circuit currents, but their use has been extended to many other areas such as power system stability, protection and coordination, contingency / reliability, economic modelling, etc.

This article provides a list of the most common software packages used for power systems analysis, and surveys both commercial and non-commercial software (listed in alphabetical order by vendor name).

## Commercial Software

### Advanced Grounding Concepts (WinIGS)

WinIGS is software for "Integrated Grounding System" (IGS) analysis. It has a straightforward graphical user interface (GUI) allowing quick and simple modelling of ground grids. After creating the model, you can observe effects of different fault current magnitudes applied to the grid and identify areas where touch and step voltage potential thresholds are exceeded (see Earthing Calculation - Touch and Step Potential Criteria. If necessary, one can easily go back to the model and mitigate for those personnel safety violations by adding bare copper conductor and ground rods (see general note below).

- Software Note: Soil resistivity layer profiles are limited to two layers. The benefit is extremely quick solution times compared to a program that may run for an hour or so with a complicated soil model. Unfortunately, the results may not be as accurate and this could be life-threatening in areas with larger fault current sources and undersized ground grids.

The second function is the lightning analysis tool. There is a preset 3D library of substation equipment (bulk supply transformers, circuit breakers, switches, rigid bus structures, etc) where the user can input length, width, and height dimensions to create a full replica of the substation to then use for lightning protection design in the form of lightning mast structures and static shield wire. If one wants to save time and be more conservative, they can easily model all of the equipment as blocks. The tool allows one to apply either fixed angel theorem (recommended for 69kV, 350kV-BIL systems or below) or the rolling sphere method (some 69kV, 350kV-BIL yards and typically voltages above 69kV), but not both simultaneously (at this time). Note that it is easy to switch between the two when observing different sections of the substation yard. See IEEE 998-1996, Guide for Direct Lightning Stroke Shielding of Substations for more information on lightning protection.

- General Note: The size of copper depends on the available amount of fault current, and typical sizes are 4/0 (212kcmil), 250kcmil, 300kcmil, 350kcmil, and 500kcmil. Ground rods are typically Copperweld copper-clad (copper-covered) steel, and are 8ft or 10ft. They can also be coupled together to achieve desireable, lower resistivity soil layers that may

See the website for a description of the expanded capabilities in the program, such as modelling remote substations as one network and calculating the system impedance, and others.

Supported Operating Systems: Windows 2000, Windows XP, Windows Vista, and Windows 7

### ASPEN

ASPEN (Advanced Systems for Power Engineering) are a California based company that develops the following separate Windows platform products:

- OneLiner - short circuit and relay coordination program (and the Breaker Rating Module add-on checks the rating of circuit breakers against the short circuit currents they need to interrupt)
- DistriView - integrated suite of voltage drop, short circuit, relay coordination, and harmonics and reliability calculation software for utility distribution systems
- Power Flow Program - power flow program designed for the planning, design and operating studies of transmission, sub-transmission and distribution networks (includes a BASIC-style scripting language)
- Line Constants Program - calculates electrical parameters of overhead transmission lines and underground cables
- Relay Database - a repository of relay information for electric utilities and industrial facilities
- Line Database - an electronic depository of data related to power lines and cables

### BCP Switzerland (NEPLAN)

BCP Switzerland are a Zurich-based company and the developers of NEPLAN, a modular power systems analysis package.

NEPLAN has the following modules: load flow, short circuit, contingency analysis, motor starting analysis, OPF, line parameter calculations, network reduction, harmonic analysis, investment analysis, dynamic simulation, reliability analysis, overcurrent and distance protection, earthing analysis, load forecasting, network optimisation tools, arc flash analysis and cable sizing. NEPLAN also features a C/C++ based programming language and MATLAB interface.

### Commonwealth Associates (Transmission 2000)

Commonwealth Associates Inc are a Jackson, Michigan based company specialising in transmission and distribution services. Transmission 2000 is a proprietary product developed by Commonwealth Associates for the analysis of utility transmission systems.

Features of Transmission 2000 include load flow, constrained economic dispatch, transient stability, short circuit, protection analysis and calculation of line constants.

### CYME

CYME International is a Canadian firm (now part of the Cooper Power Systems family) that develops an integrated suite of modular power engineering applications, as well as standalone applications for cable ampacity calculations and electromagnetic transients.

The integrated suite has a range of functions including load flow, short circuit, OPF, load balancing, load allocation / estimation, optimal capacitor placement, network forecaster, reliability, transient stability, harmonic analysis, dynamic motor starting, contingency, protection coordination, switching optimisation, GIS overlay, earthing grid design and arc flash analysis.

### DIgSILENT (PowerFactory)

DIgSILENT GmbH is a German company that develops PowerFactory, a Windows-based integrated power systems modelling and analysis package. DIgSILENT PowerFactory is easy to use and caters for all standard power system analysis needs, including high-end applications in new technologies such as wind power and distributed generation and the handling of very large power systems. In addition to the stand-alone solution, the PowerFactory engine can be smoothly integrated into GIS, DMS and EMS supporting open system standards.

Some of the functions include power flow analysis, fault analysis, stability analysis, network reduction, protection analysis, electromagnetic transients analysis, motor starting analysis, OPF, harmonic load flow, state estimation, contingency and reliability assessments, overhead line and cable parameter calculation, distribution network analysis, eigenvalue / modal analysis.

Features include a C++ style scripting language called the DPL and a single, integrated, flexible database.

### DNV GL (SynerGEE Electric)

SynerGEE Electric is a power system analysis package developed by DNV GL. Functions include load flow, symmetrical and asymmetrical faults, capacitor placement, cable ampacity, contingency switching, switch optimization, harmonic impedance, motor starting, phase balancing, predictive reliability, and protective device coordination.

### Energy Advice (EA-PSM)

EA-PSM is a power system modelling software for electrical engineers developed by Energy Advice based in Lithuania, Europe. Features include power flow, short circuit, arc flash, harmonic load flow, protection coordination, distance protection and coordination, motor starting, cable ampacity, protection tracking, parallel lines parameters calculations, low and medium voltage cable sizing, power transformer harmonic losses evaluation module. All models are based on IEEE, IEC and GOST standards.

### Energy Computer Systems (SPARD)

Energy Computer Systems is a Colombian company that develops SPARD mp Power, an integrated power systems analysis software package.

Functions include load flow, short circuit, harmonic analysis, automatic protection coordination, transient stability, OPF and optimisation tools.

### Electrocon (CAPE)

Electrocon International are a Michigan based company and developers of the Computer Aided Protection Engineering (CAPE) software, a Windows-platform protection tool designed for high voltage transmission systems and distribution systems within electric power utilities. CAPE was first released in 1990.

Functions include short circuit analysis, protection coordination, relay settings and checking with a system simulator, load flow, OPF, short circuit reduction, breaker duty evaluation and line constants calculations.

### EMTP-RV

The ElectroMagnetic Transients Program (EMTP) was first developed by Prof. Hermann Dommel in the 60s/70s for the analysis of electromagnetic transients. It was commercialised in 1987 and released as DCG EMTP and later EMTP96. EMTP-RV is the latest commercial released of the program, created by Jean Mahseredjian and currently being developed by POWERSYS.

### EPFL (SIMSEN)

SIMSEN is a simulation software package for the analysis of power systems and adjustable speed drives. It is developed by the École Polytechnique Fédérale de Lausanne (EPFL). Analysis features include the simulation of electromagnetic transients in AC/DC networks, transient stability, general fault analysis and sub-synchronous Resonance (SSR).

### ERACS

ERA Technology are a UK-based consultancy that also develop the power system analysis program ERACS. Features include: load flow, short circuit, arc flash analysis, harmonic studies, transient stability and protection coordination.

### EasyPower

EasyPower LLC, founded in 1990 and based in Oregon, are the developers of EasyPower®, an integrated power systems analysis software, with an array of products such as EasyPower®, EasySolv™, SafetyTracker™ and Oneline Designer™. The flagship product, EasyPower, includes the following modules: arc flash analysis, power flow, short circuit, OPF, protective device coordination, dynamic stability, transient motor starting, and harmonic analysis.

Additional workflow enhancing modules include SmartPDC™, which automates protective device coordination, and SmartDesign™ which automatically sizes feeders, breakers, switchgear, fuses, busway, MCCs, panels, etc to NEC requirements. The ScenarioManager feature allows the study of multiple system scenarios on the fly.

Oneline Designer is a cost effective solution for people who are dedicated to creating onelines, as well as system data collection and entry.

### ETAP

Founded in 1986 and headquartered in Irvine, California, ETAP is a company specialising in electrical power system modeling, design, analysis, optimization, and predictive real-time solutions. To date, more than 50,000 licenses of the Company’s ETAP and ETAP Real-Time products have been used in generation, transmission, distribution, and industrial power system projects around the world.

Functions include arc flash analysis, load flow analysis, short circuit analysis, motor starting, OPF, transient stability analysis, generator start-up, parameter estimation, cable sizing, transformer tap optimization, reliability assessment, transmission line constant calculations, harmonic analysis, protection coordination, dc load flow, battery discharge and sizing, earth grid design, cable pulling, and GIS map integration.

### GDF Suez (Eurostag)

Eurostag is a package developed by Tractabel Engineering GDF Suez and RTE (France), which includes the following functions: load flow, dynamic simulation, critical clearing time calculation, eigenvalue computation and system linearisation, dynamic security assessment, model parameter identification and small signal analysis. One of the more unique features of Eurostag is the out-of-the-box modelling of power plant mechanical / energy conversion equipment such as boilers, gas turbines, etc.

### GE Energy (PSLF)

GE Energy develop a range of utility software including PSLF (Positive Sequence Load Flow), a suite of analytical tools that can simulate large-scale power systems up to 60,000 buses.

Functions include load flow, OPF, short circuit and dynamic simulation. Includes support for a scripting language called EPCL.

### IPSA Power

IPSA Power is a division of UK company TNEI that develops the IPSA (Interactive Power System Analsysis) software package. IPSA was started as a PhD project in 1954 and the first commercial version was released in 1980.

Functions include load flow, short circuit, OPF, transient and dynamic stability, harmonic analysis, protection coordination. A Python-based scripting language is supported, as well as an open API for use in other applications (with Visual Basic / VBA, C/C++ and Fortran bindings).

### KEPCO (KW-PSS)

KEPCO Research Institute is a branch of the Korean company KEPCO (Korea Electric Power Corporation). In 2002, they started development on KW-PSS, a power systems analysis package with the following modules: Power Flow Analysis & Fault Analysis, Transient Stability Analysis, Voltage Stability Analysis, Small Signal Stability Analysis and Optimal Power Flow & Optimal Capacitor Placement.

### MATMOR (PADEE)

MATMOR C.A. is a Venezuelan engineering consultancy that also develops PADEE, a network analysis, design and planning package for low and medium voltage distribution networks.

Standard modules in PADEE include Intelligent Maps Program (IMP), Primary Network Analysis Program (PNAP), Secondary Network Analysis Program (SNAP), Customers Program (CP), Transformer Load Management Program (TLMP), Equipment Information and Photo Program (EIPP), Demand Forecast for Short, Medium and Long Term Program (DFP), Overcurrent Protection Coordination Program (OPP), Automated Topographic Profiles Drawing and Pole Placing Program (ATPPP), Budget Calculation Program (COMWIN), Interrupts and Operation Program (IOP), Energy Loss Program (ELP), Distribution Network Maintenance Program (DNMP), Network Inventory, Public Lighting and Other Services Program (NILOP), Connection with SCADA Program (CSCP) and Transformer Bank Totalizer Program (TBTOTP).

### MILSOFT (Windmil)

MILSOFT Utility Solutions are a Texas based company that develops Windmil, an electric distribution system planning and analysis package. Functions include load flow and voltage drop modeling, reliability analysis, contingency and sectionalizing studies, OPF, short circuit and fault current calculations, protective device coordination and arc flash hazard analysis.

### Manitoba HVDC Research Centre (PSCAD)

Manitoba Hydro International is a Canadian company with a research arm called the Manitoba HVDC Research Centre that develops the software packages PSCAD (also known as PSCAD/EMTDC).

PSCAD is an electromagnetic time domain transient simulation environment and study tool, created in 1988 and first released commercially in 1993. It is a multi-purpose dynamic simulator with particular specialisation in HVDC applications.

### MathWorks (SimPowerSystems)

Mathworks, the makers of general purpose mathematical software MATLAB, also develop an power systems simulation program. SimPowerSystems is a tool that extends MATLAB's Simulink and provides models of many components used in power systems, including three-phase machines, electric drives, and libraries of application-specific models such as Flexible AC Transmission Systems (FACTS) and wind-power generation. Harmonic analysis, calculation of Total Harmonic Distortion (THD), load flow, and other key power system analyses are automated.

### MicroTran

MicroTran Power Systems Analysis Corporation is a spinoff company of the University of British Columbia (UBC), where the founders H. W. Dommel, J. R. Marti and L. Marti are (or were once) based. MicroTran is the UBC version of the electromagnetic transients program EMTP.

### Nexant (SCOPE)

Nexant is a California based company that develop SCOPE, an integrated set of power system analysis tools intended for network operations. Functions include load flow, contingency analysis, security constrained OPF and market simulations.

### Phase to Phase (Vision Network Analysis)

Phase to Phase BV is a Dutch company and the developers of the Vision Power Range software products. Vision Network Analysis has functions including load flow, short circuit, reliability, protection and harmonic analysis. The software also includes a built-in programming language for macro / script creation, as well as GIS integration.

### Power Analytics (EDSA)

Power Analytics is a California based company that develop the Paladin suite of software products (formerly called EDSA). Paladin DesignBase is an integrated power systems modelling and analysis tool.

Functions include load flow, short circuit, arc flash simulations, OPF, reliability and capacity, protection coordination, optimal sizing and placement of reactive power sources, dynamic simulations, harmonic analysis, sizing tools (battery, cable, generator set, conduit, motor parameter estimation, etc), cable pulling and earth grid design.

### Powertech Labs (DSATools)

Powertech Labs are a subsidiary of Canadian utility BC Hydro and developers of the dynamic security assessment and power systems analysis package DSATools. The tools are primarily designed for online dynamic security assessment.

DSATools comprises four main modules:

- PSAT: Power flow and short circuit analysis tool
- VSAT: Voltage stability analysis tool
- TSAT: Transient stability analysis tool
- SSAT: Small signal analysis tool

### PowerWorld

PowerWorld Corporation are a Champaign, Illinois based firm that develop the PowerWorld Simulator suite of power systems analysis tools for Windows. The software focuses on a visual approach to power system simulation.

Functions include load flow, short circuit, contingency analysis, sensitivity calculations, security constrained OPF, transient stability, transmission line parameter calculations. Includes scripting support.

### PRDC (MiPower)

MiPower is an Indian product developed by Power Research and Development Consultants (PRDC) - a Bangalore based consulting and software development company. MiPower is the flagship product of PRDC comprising of a wide range of software applications for the design, analysis and simulation of electrical power system (transmission, distribution and generation systems). PRDC also owns several other products like Hydro-thermal Co-ordination, Web-based packages, Renewable Energy Scheduling, Energy Auditing, Automated Fault Analysis System and several other hardware and firmware for the power system community.

The history of MiPower dates back to a few decades and was among the first products that had a graphical user interface. MiPower has been built with expertise from over four decades of system operation, consulting and R&D in a country with one of the world's largest and most complex networks. Today, MiPower is based on the state-of-the-art technologies and runs on the latest Windows Operating System. Users of MiPower range from Canada to Japan and UK to Fiji Islands.

The functions of MiPower include load flow, short circuit, Eigenvalue analysis, 3-phase load flow (3pLFA), optimal power flow, contingency ranking and analysis, transient stability, motor starting, protection, EMT analysis, harmonic analysis, SSR, voltage stability analysis, long-term forecasting, network reduction, ground grid design, reliability, DC load flow and short circuit and battery sizing.

### ReticMaster

ReticMaster is a Windows-based tool from South Africa designed for the analysis of radial networks. Functions include load flow, short circuit, motor starting and protection coordination.

### SES & Technologies (CDEGS)

Safe Engineering Services & Technologies Ltd (SES; SES & Tech) is the world leader in grounding, lightning, and electromagnetic interference computations. They are developers of CDEGS (Current Distribution, Electromagnetic Fields, Grounding and Soil Structure Analysis), a grouping of software modules described as "a powerful set of integrated engineering software tools designed to accurately analyze problems involving grounding / earthing, electromagnetic fields, electromagnetic interference including AC/DC interference mitigation studies and various aspects of cathodic protection and anode bed analysis".

The package includes the following:

- RESAP: Soil Resistivity Analysis
- MALT: Low Frequency Grounding / Earthing Analysis
- MALZ: Frequency Domain Grounding / Earthing Analysis
- TRALIN: Line and Cable Constants (Parameters) & Induction Analysis
- SPLITS: Detailed Fault Current Distribution and EMI Analysis
- HIFREQ: Electromagnetic Fields Analysis
- FFTSES: Automated Fast Fourier Transform Analysis
- FCDIST: Simplified Fault Current Distribution Analysis

Per the website, CDEGS capabilities are:

- Soil resistivity analysis and soil structure interpretation.
- Grounding analysis: arbitrary soil structures; any frequency & transients.
- Line constants for overhead and buried conductors or complex pipe-enclosed cable arrangements.
- Load, fault & transient current distribution (in neutrals, shields, etc.).
- Cathodic protection analysis of complex buried networks.
- Inductive, conductive and capacitive interference in shared corridors.
- Frequency and time domain analysis of electromagnetic fields generated by arbitrarily energized conductor networks (substations, transmission & distribution lines, industrial plants, etc.)

Supported Operating Systems: Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1

### Siemens PTI (PSS/E and SINCAL)

Siemens PTI is the consulting, software and training arm of Siemens AG. Siemens PTI offers the Power Systems Simulator (PSS) product suite, which includes among others:

- PSS®E
- PSS®SINCAL

The Power System Simulator for Engineering (PSS/E) was one of the first GUI-based power systems analysis software, and was first released in 1976. It was purchased by Siemens in 2005.

Functions include load flow, short circuit, dynamic simulations, OPF, contingency analysis (probabilistic and deterministic), protection, eigenvalue / modal analysis, harmonics and small signal stability. User-defined scripts can be created using a Python-style scripting language.

Siemens Network Calculator (SINCAL) is a software pacakage with planning tools for electricity as well as pipe networks (gas, water, heating / cooling). Functions relevant to power systems analysis include load flow (balanced and unbalanced), short circuit, time-domain dynamic simulations, eigenvalue and modal analysis (integrated with PSS®NETOMAC), harmonic analysis, protection simulations (integrated with PSS®PDMS), reliability and contingency analysis.

### SIMPOW

SIMPOW is an integrated power systems analysis software package. Functions include load flow, short circuit, transient stability, voltage stability, small signal stability, SSR analysis, harmonic analysis and frequency scans. SIMPOW was originally developed by Manitoba HVDC Research Centre, but as of May 2014, ownership was transferred to Solvina.

### SKM (Power*Tools for Windows)

SKM Systems Analysis are a California-based corporation that develop Power*Tools for Windows (PTW), an integrated suite of power systems analysis tools aimed at industrial systems. The original software, called DAPPER, was first released in 1978, though the initial version of PTW wasn't released until 1995.

Functions include load flow, short circuit, demand load analysis, OPF, load schedules, feeder and transformer sizing, protection coordination (CAPTOR), arc flash analysis, transient motor starting (TMS), harmonic analysis (HI_WAVE), transient stability (I*SIM), distribution reliability, earth grid design (GroundMat), dc load flow and short circuit analysis, battery sizing, cable pulling analysis and equipment evaluation.

### Tom (PASHA)

TOM Industrial Consultants CAD / CAM are an Iranian company and the developers of PASHA (Power Apparatus & System Homological Analysis). PASHA modules include load flow, short circuit, OPF, transient stability, motor starting, motor parameter estimation, reliability, harmonic analysis and protection.

### Xendee

Xendee is a San Diego based company providing cloud computing web applications for the design and simulation of multi-phase unbalanced and three-phase balanced power systems, along with micro-grids and next generation utility distribution systems.

Xendee works within most modern browsers on Apple Mac or Windows PCs, and integrates the Electric Power Research Institute's (EPRI) Open Distribution System Simulator (OpenDSS) analytics, and implements gamification in the user interface techniques to offer an interactive and game-like experience. Nearly all frequency domain simulations such as power flow and short circuit analysis are supported.

## Non-Commercial Software

### AMES

AMES is a free open source software package for agent-based modelling of wholesale electricity markets (based on DC optimal power flow analysis).

### DCOPFJ

DCOPFJ is a free open source "Java solver for bid/offer-based DC optimal power flow (DC-OPF) problems suitable for research, teaching, and training applications. The DCOPFJ package consists of two linked parts: an internal solver QuadProgJ for strictly convex quadratic programming problems, and an outer shell that automates input data preprocessing and output data display".

### ATP-EMTP

The Alternative Transients Program (ATP) is a free (closed source) program for the digital simulation of electromagnetic (and electromechanical) transient phenomena. ATP-EMTP was first developed in 1984.

### DiSC

DiSC - A Simulation Framework for Distribution System Voltage Control - is an open source MATLAB simulation framework for verifying voltage control approaches in European power distribution systems. It follows the mission of IEEE Task Force on Open Source Software for Power Systems.

### Dome

Dome is a Python-based project by Frederico Milano (creator of PSAT). Dome is a command-line application and can currently solve load flows, continuation power flow, time domain simulation including the quasi-static one, small signal stability analysis and optimal power flow.

### Elplek

Elplek is a freeware short circuit, protection coordination and load flow calculation application for Windows developed by Ilkka Leikkonen.

### GridCal

GridCal is an open-source power systems analysis package written in Python, complete with a PyQT GUI frontend.

### GRIDLAB-D

GRIDLAB-D is a power distribution system simulation and analysis tool first released in 2008 by the U.S. Department of Energy (DOE) at Pacific Northwest National Laboratory (PNNL). GRIDLAB-D is an agent-based simulator for distribution systems that integrates a range of objects / actors in the energy system, e.g. residential loads, climate / weather, energy storage, distributed generation, demand response, etc. The simulator is held together by a three-phase power flow, which runs at every time step.

### GridPACK

GridPACK is an open source project aimed at developing "a framework to support the rapid development of power grid applications capable of running on high performance computing architectures (HPC) with high levels of performance and scalability." (GitHub Repository)

### InterPSS

InterPSS (Internet technology based Power System Simulator) is a free, open source power systems analysis package built in Java by a team of international developers from the US, Canada and China. InterPSS is an integrated package that can run load flow, short circuit, transient stability and power transfer analysis.

### MatDyn

MatDyn is an open source extension of MATPOWER for the dynamic analysis of power systems.

### MATPOWER

MATPOWER is a Matlab-based power systems simulation package developed at Cornell University. MATPOWER can solve load flow and optimal power flow problems, and "is intended as a simulation tool for researchers and educators that is easy to use and modify".

### Minpower

Minpower is an open source Python-based toolkit for solving economic dispatch, optimal power flow and unit commitment problems. It was first developed in 2011.

### Mosaik

Mosaik is a smart grid co-simulation framework written in Python that allows for discrete event-based simulations combining existing models and simulators. For example, at each time step, a household load model / simulator may calculate load demand, a battery model may calculate state of charge, a photovoltaics model may calculate generated PV output and this is all interfaced by a load flow simulator.

### NEMO

NEMO, the National Electricity Market Optimiser, is a chronological dispatch model for testing and optimising different portfolios of conventional and renewable electricity generation technologies (not to be confused with the Nucleus for European Modelling of the Ocean!) It has been developed since 2011 and is maintained by Ben Elliston at the Centre for Energy and Environmental Markets, University of New South Wales.

### OpenDSS

OpenDSS (Distribution System Simulator) is an open source project by the Electric Power Research Institute (EPRI). OpenDSS is Windows-based and "supports all rms steady-state (frequency domain) analyses commonly performed on electric power distribution systems, such as power flow, harmonic analysis and fault current calculations."

### pandapower

pandapower combines the data analysis library pandas and the power flow solver PYPOWER to create an easy to use network calculation program aimed at automation of power system analysis and optimization in distribution and sub-transmission networks.

pandapower is a joint development of the Department for Distribution System Operation, University of Kassel and the Department for Distribution System Operation at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES), Kassel.

### PowerGAMA

PowerGAMA is an open-source Python package for power system grid and market analyses.

It is a lightweight simulation tool for high level analyses of renewable energy integration in large power systems. The simulation tool optimises the generation dispatch, i.e. the power output from all generators in the power system, based on marginal costs for each timestep over a given period, for example one year. It takes into account the variable power available for solar, hydro and wind power generators. It also takes into account the variability of demand. Moreover, it is flow-based meaning that the power flow in the AC grid is determined by physical power flow equations.

### PSAT

The Power Systems Analysis Toolbox (PSAT) is a Matlab-based package developed by Frederico Milano for power systems analysis and simulation. Functions include load flow, OPF, small signal stability analysis and time domain simulation.

### PYPOWER

PYPOWER is a port of MATPOWER to Python.

### PYPOWER-Dynamics

PYPOWER-Dynamics is a transient stability extension module for PYPOWER. There is fairly extensive documentation on the PYPOWER-Dynamics wiki.

### PyPSA

PyPSA stands for "Python for Power System Analysis". It is pronounced "pipes-ah".

PyPSA is a free software toolbox for simulating and optimising modern power systems that include features such as variable wind and solar generation, storage units, sector coupling and mixed alternating and direct current networks. PyPSA is designed to scale well with large networks and long time series.

### RAMSES

RAMSES is a software for time simulation of electric power systems in phasor mode (quasi-sinusoidal approximation). It has been developed at the University of Liège, in the context of research on accelerated and parallel solvers for time simulation.

### RPowerLABS

RPowerLABS is suite of a web-based power system analysis and simulation tools from Nigeria created in the R language. It also features as an online virtual power system simulation laboratory with provisions for real-time collaboration between participants. RPowerLABS is an on-going project with support for power flow analysis, transient stability analysis, contingency analysis, fault studies, coherent generators, synchronous machine transients, transmission line calculations, economic dispatch and optimal power flow.

### SmartGridToolbox

SmartGridToolbox is a C++ library for developing discrete event-based simulations. The SmartGridToolbox was developed by National ICT Australia (NICT) in collaboration with ANU and Actew-AGL.

### TEFTS

TEFTS is an open source program for DOS and UNIX "designed to do transient stability and energy function analyses of reduced dynamic models of ac/dc power systems, with additional capabilities for voltage stability (bifurcation) studies based on continuation methods. This package is not designed for "commercial grade" studies, but rather for research and teaching purposes."

### UWPFLOW

UWPFLOW is an open source Windows and UNIX-based toolset "designed to calculate local bifurcations related to system limits or singularities in the system Jacobian. The program also generates a series of output files that allow further analyses, such as tangent vectors, left and right eigenvectors at a singular bifurcation point, Jacobians, power flow solutions at different loading levels, voltage stability indices, etc".

### vSPD

vSPD stands for vectorised Scheduling, Pricing and Dispatch - an audited, mathematical replica of SPD, the pricing and dispatch engine used in the New Zealand electricity market.