Load Flow Analysis
Within the Load Flow analysis environment, the accurate representation of a variety of network configurations and power system components is possible. Any combination of meshed 1-, 2-, and 3-phase AC and/or DC systems can be represented and solved simultaneously, from HV transmission systems, down to residential and industrial loads at the LV voltage levels. The Load Flow tool accurately represents unbalanced loads, generation, grids with variable neutral potentials, HVDC systems, DC loads, adjustable speed drives, SVS, and FACTS devices, etc., for all AC and DC voltage levels.
DIgSILENT PowerFactory also incorporates an enhanced non-decoupled Newton-Raphson solution technique, with current or power mismatch iteration, and typical round-off errors below 1 kVA for all buses. The superior stability and convergence of the implemented algorithms is making other traditional load flow methods such as Current Iteration obsolete. Several iteration levels are guaranteeing convergence under all conditions. If for example the Load Flow is tending towards divergence, due to unrealistic constraints, the solution algorithm will analyze the constraints and modify them automatically.
DIgSILENT PowerFactory is introducing a new, intuitive and easy-to-use modeling technique fully avoiding the definition of bus types such as SL, PV, PQ, PI, AS or any other definition often required to model special devices. PowerFactory simply provides such control mechanisms and devices characteristics which are found in reality.
More Load Flow Analysis Features
- Supports device characteristics, such as loads with voltage dependency and asynchronous machines with saturation and slip dependency, etc.
- Practical station control features with various local and remote control modes for voltage regulation and reactive power generation. Reactive power is automatically adjusted to ensure that generator output remains within its capability chart.
- Comprehensive area/network power exchange control features using Secondary COntrollers (SCO) with flexible participation factors.
- Transformer OLTC able to control local or remote bus voltages, reactive power flows as well as voltage-drop compensation (LDC) within distribution systems.
- Devices controllers for shunts, double-fed asynchronous machines and other power electronics elements such as PWM converters, inverters, rectifiers or integrated FACTS devices.
- Local and remote control mechanism for SVS systems. Automatic and continuous control of the TCR and TSC switching is performed within component ratings to hold voltage at a given value.
- Correct representation of transformer vector groups and phase displacement.
- Shunts can be modeled to consist of a combination of series and/or parallel connected capacitors, reactors and resistors. Shunts can be connected to busbars and feeders or to the remote end of cables and lines. Filters may consist of any number of shunt combinations. Automatic shunts switching can be included in the automatic voltage regulation.
- Full support of any parameter characteristic and scale to allow parametric studies or easy definition of loading scenarios or load profiles.
Contingency Analysis
The new DIgSILENT PowerFactory Contingency Analysis functions have been designed to offer a high degree of flexibility. There are now three different ways that contingency analyses can be carried out:
- By analyzing a single contingency. This is achieved by selecting one or more objects for simultaneous outage, and running a load flow case to analyze the outage.
- By creating one or more contingencies, each of which may define one or more objects to be taken out of service simultaneously. Load flows are then run to analyze all outage combinations
- By running a DPL script that specifies certain contingencies, which are then analyzed sequentially.
A detailed report of each contingency case for each option is available after the analysis has been completed.
Further Special Functions
- Analysis of system control conditions
- Calculation of dV/dQ sensitivities.
- Parameter scaling for the determination of voltage stability curves (V-P) and transfer limits (Voltage Stability Analysis)
- Determination of "Power at Risk"
- Automatic Outage Simulation (n-1), including detailed reports for user-defined voltage limits and equipment overloading
- Support of DPL scripts e.g. to perform load balancing, determination of penalty factors or any other parameter required.
Load Flow Results
- Display of any variable within the single line and station diagram according to a most flexible VI definitions;
- Fully flexible filter mechanisms to display objects in colored mode;
- Detailed analysis reporting, which can list overloaded system elements, unacceptable bus-voltages, islanded system areas, out of service components, voltage-levels, area summaries, and many other documentation features;
- Detailed text output with pre-defined or user-defined filters and levels;
- Support of the Flexible Page with free variable definition and DPL interactivity;
- Result export to other software system such as MS-EXCEL
Radial Feeder Analysis
DIgSILENT PowerFactory provides a number of special functions that make LV analysis more transparent and adopted to practical constraints.
Feeder Plots
Using the most innovative "Feeder plot" a special, high level graphical display feature (Virtual Instrument, VI) is provided to increase transparency in grid loading and voltage profile analysis across several voltage levels. Full interactivity is given to access via the VI all relevant data and structures.