Power flow analysis/studies is the preliminary step used in any Power Evacuation Studies.
Power flow calculations provide active and reactive power flows and bus voltage
magnitude and their phase angle at all the buses for a specified power system configuration and
operating condition subject to the generation and/or regulating capabilities of generators, synchronous
condensers, static var compensators, HVDC controls, FACTS controllers, tap changing
under load transformers and specified net interchange between individual operating
systems (utilities). This information is essential for the continuous evaluation
of the current performance of a power system and for analyzing the effectiveness
of alternative plans for system expansion to meet increased load demand. These analyses
require the calculation of numerous power flow cases for both normal, and emergency
(contingency) operating conditions. The output from power flow studies often
provide the initial conditions needed for other analysis, such as short circuit
studies, transient stability, economic dispatch, dynamic stability studies.
Applications of Power Flow Study and Analysis
Power flow study has the following applications
- Transmission expansion planning , operation planning
- Distribution expansion planning , operation planning
- Industrial/Commercial distribution system planning, operational planning
- Network interconnection, Grid interconnection studies
- Evaluation of energy transactions between various stake holders
- Energy audit to accurately determine network losses and estimate billing losses if any
- Sizing of transformers, cables, overhead lines, transformer tap ranges, shunt
capacitors, shunt reactors, reactive power management, FACTS devices, HVDC
- System security assessment via static contingency studies
- Decision making tool in operation planning and operation of the system in load dispatch center
- Motor starting studies using load flow type analysis, where the starting
impedance of the Induction motor is modeled as constant impedance model with
- Evaluation of static voltage stability using load flow technique
The following general criteria
of acceptability of design is used in power flow studies
Voltage Drop at all buses should be within +/- 5% of the nominal rating for all
operating conditions considered
over load conditions of any electrical circuits for all operating conditions
Reactive power generation/import/export to be within specified limits for all
operating conditions considered
power supply to all loads, under specified contingency conditions, as per design
The following study cases/ power flow outputs are generally considered in power
Extreme operating conditions of maximum and minimum loading conditions will be
considered to check the adequacy of the network, even though some of these
conditions may not exist during normal operation
Contingency conditions such as outage of lines, transformers, generators will be
considered and network adequacy for power evacuation will be assessed
Operating solutions such as transformer
taps, Generator Excitation, shunt reactive power compensations will be provided
Recommendations for strengthening and equipment upgradations will be provided to
meet specific operating requirements.
Summary of load flow studies and concise reports in tabular formats and single
line diagram formats will be provided
, along with the summary of
Contingency evaluation studies typically refers to evaluation of network adequacy
and security under credible network element outage conditions.
Typically outage of important transmission lines , transformers, generating
units are usually considered in the evaluation. The evaluation is carried out by
using static as well as dynamic analytical tools such as load flow analysis and
transient stability analysis. Real time control and monitoring solutions in
enercy control centers or energy management systems or load dispatch centers
usually use an algorithm called contingency ranking algorithm to shortlist
credible contingencies for real time evaluation and control of power systems.
Often contingency ranking algorithm will use some approximate and fast load flow
type algorithms from a list of contingencies and rank them in the decreasing
order of severity.
This ordered or ranked list will be considered for a detailed contingency
evaluation to assess system security.
Power Flow is the analysis module of PowerApps dedicated to power flow analysis
in three-phase electric power networks. It is equipped with powerful analytical
options and alternative solution techniques.
AC/DC Load Flow, FACTS devices.
Load flow solution of multiple-islanded systems. The solution is available for each
of the islands having a reference (slack) node. The reference node is automatically
identified by the algorithm as the largest generator node in each island.
Limit violation reports, summary reports.
Unbalalanced 3 phase load flow, including 1 and 2 phase load flow for lines drawn
separately from a 3 phase supply point.
Choice of objectives for the OPF/RPO (Transmission loss minimization, Voltage Stability
improvement, Removal of operating violations, Economic dispatch).
Optimal Load Flow.
OPF/RPO control options are – active power injections, reactive power injections,
shunt compensations, series compensations, phase shifters, transformer taps.
OPF/RPO sensitivity calculations with respect to the performance objective provides
information for suitable location of shunt reactive power compensation and also
identifies most effective controllers for optimization.
No limits on the number of study cases and related reports in a single execution
of the program
Comparison Document for Load Flow Calculations between ETAP and PowerApps [Right click to Save As]
Validation Document for Load Flow Calculations of PowerApps [Right click to Save As]
Equivalent Generator Representation for Power System Analysis
Download Comparison Document for Load Flow Studies