General Capabilities
PowerFactory’s high precision time-domain RMS- and EMT -simulation kernel, complemented by a comprehensive model library and a user-definable, graphical modelling function (DIgSILENT Simulation Language (DSL)), provides a flexible and powerful platform for solving both, system stability and electromagnetic simulation tasks.
Grid Modelling Capabilities
- Simulation of radial and meshed 1-, 2-, 3- and 4-phase AC and/or DC systems
- Modelling validity ranging from low-voltage (LV) up to ultra high-voltage (UHV)
- Distributed generation modelling and simulation capabilities
- High precision wind power models of various technologies
- Balanced and unbalanced grid loading conditions
- Simulation of railway systems
Advanced Simulation Models
- High precision models for both solid and salient pole synchronous machines, asynchronous machine model including a doubly-fed induction machine model with integrated or externally connected PWM converter.
- VSD (Variable Speed Drives) systems, PWM converter and other power electronic elements such as the softstarter, inverter and rectifier. In general, all available power system elements are also supported for stability simulations.
- General load models where load inertia, bus voltage and frequency dependence is represented; a special lumped load model to accurately represent feeders containing a high percentage of motor load (RMS only). The capability of modelling motor stall effects is included, and was developed on the basis of comprehensive system tests.
- Generic wind turbine models with doubly-fed induction generator, direct driven synchronous generator and asynchronous generator with static compensation (STATCOM).
- Manufacturer-specific high-precision wind turbine models are available upon request.
- Large library of IEEE controller models covering prime movers, automatic voltage regulators (AVR) and power system stabilizers (PSS).
- Support of the comprehensive DIgSILENT Protection Library in stability mode.
RMS Grid Representation
Based on a converged load flow, the calculation of initial conditions is carried out prior to the start of a dynamic RMS- or EMT-simulation offering the following grid representation options:
RMS simulation only
- Positive sequence only - the classical RMS representation for stability studies
RMS and EMT simulation
- a-b-c phase RMS representation supporting unbalanced grid loading initialized by a balanced or unbalanced load flow, featuring precise definition of any unbalanced grid fault condition including single- and double-phase line interruptions. This system representation mode avoids tedious hand-calculations of equivalent fault impedance and allows access to any a-b-c phase quantity for plotting or precise modelling purposes (e.g. protection devices).
RMS Simulation Algorithms
- Highly accurate, fixed or variable step-size integration technique for solving AC and DC network load flow and dynamic model equations. This is combined with a non-linear electromechanical model representation to enable a high degree of solution accuracy, algorithmic stability and time range validity.
- A-stable simulation algorithm for the efficient handling of stiff systems. This is applicable to all or any individually selected model featuring error-controlled automatic step-size adaptation, ranging from milliseconds up to minutes or even hours, including precise handling of interrupts and discontinuities.
EMT Simulation Algorithms
- The calculation of initial conditions is carried out prior to the EMT simulation, and is based on a solved load flow (symmetrical or asymmetrical). Consequently, there is no need for saving steady state conditions being reached after transients are damped out aiming in simulation re-starting under steady state conditions.
- Special numerical integration methods have been implemented in DIgSILENT PowerFactory in order to avoid numerical oscillations caused by switching devices and other non-linear characteristics.
- Highly accurate, fixed or variable step-size integration technique for solving AC and DC network transients and dynamic model equations. This is combined with a non-linear electromechanical model representation to enable a high degree of solution accuracy, algorithmic stability and time range validity.
Faults and Interrupt Handling
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- By activating predefined fault types, or by accessing and modifying PowerFactory variables, any type of fault can be implemented. Typical faults are:
- Tripping of any power system element such lines, transformers, feeder loads or generators;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Application and clearing of faults at substations or along lines;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed. >Opening and closing of circuit breakers – e.g. simulating load shedding, shunt switching, starting/tripping of synchronous and asynchronous machines, or when simulating the synchronization of isolated areas via synchro-check relays;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Introduction of “Parameter Change Events” featuring the modification of any built-in and DSL model parameter;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Definition and introduction of inter-circuit events;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Generation of message- and outage-events;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Modification of integration step sizes;
- The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
- Event-driven modification of variables and signals either manually, via DSL models or by reference to external measurement files.
Simulation Output Processing
- Any PowerFactory variable, or any quantity identified in the transmission network, built-in dynamic models or DSL models, may be selected for simulation observation or for later plotting within x/t or x/y diagrams or any other VI (Virtual Instrument) provided. In addition to these variables, the DSL algebraic expression interpreter and logical expression evaluator can be applied to generate further signals or any user-defined quantity.
- Plotting files may be retained for re-plotting in comparison with subsequent runs.
- Output window log of all simulation events, providing a detailed analysis of manually entered or automatically initiated events.
- Simulation results are stored in a proprietary binary PowerFactory file format which can be directly converted into COMTRADE files.
Special PowerFactory Stability Simulation Features
- 1-click simulation utilizing PowerFactory project and study case definition
- Real-time simulation mode with user-defined real-time synchronisation periods (RMS only)
- Parallel and sequential synchronization for integrated simulation, e.g. for simulation certain grid sections in RMS mode whilst others are simulated in EMT mode.
- Real-time inter-process signal communication via OPC link
- A/D and D/A interfacing capabilities (e.g. hardware-in-the-loop simulation)
