Labels correspond the associated described change.*

• indicates that some methods were deprecated;
• indicates a breaking change which could impact all users;
• indicates a change in the simulation results that may affect existing tests in your application;
• indicates a new parameter, a new parameter default or a new parameter usage;

📜 Release notes

Reports

• Report buses out of realistic voltage range in sub reports [#1105] May change reference reports layout for tests having this error condition.

LoadFlow

• The Area Interchange control is now available in DC [#1123]. Before it was only available in AC. This features, activated by the parameter areaInterchangeControl constrains OpenLoadFlow to find a solution where area interchanges match the input target interchange values. The areaInterchangeControl parameter now impacts DC computations.

Security Analysis

• ViolationLocation are now returned for bus voltage violations. ViolationLocation allow to know the precise location of a bus related violation inside a VoltageLevel, in BusBreaker topology or in NodeBreakerTopology. [#1134]
• The criteria to stop the active power flow through a disconnected HVDC line has been modified in [#1120]. Previously an HVDC line was considered disconnected if one of its stations was connected to an isolated merged bus that was not connected to a Generator or a Load. With this fix, fictive loads are ignored. So if an HVDC station is only connected to a fictive load, the HVDC line is now considered disconnected.
• With parameter connectedComponentMode set to ALL, the security analysis now handles correctly all synchronous components of the main connected component (#1129). Previously, only the largest synchronous component of the main connected component was run. . May impact tests running SA on all components where the first connected component has several synchronous parts.
• PST actions for fast DC SA are supported [#1095]. Fast DC SA is an optional algorithm for security analysis in DC activate by the dcFastMode parameter. It is much faster than the default algorithm but has currently some limitations (see the dcFastMode parameter documentation for a list of limitations)

Robustness and accuracy

• Retry LU decomposition if incremental mode fails (#1108). This change helps in particular for the SA computation of large modes with HVDC in AC emulation that can reach or quit the maximal HVDC Active Power Range.
• Fix injections ignored on slack buses when using multi slack (#1116) . May impact the result of models using multiple slack buses that were subject this this bug.
• DC Load Flow reference bus and multi slack support [#1118]. Provides a better DC initialization for AC simulations using multiple slack buses.
• Fixed a bug in DC : incorrect transit if a PST is near zero impedance lines, or if a HVDC in AC emulation is near a zero impedance line. FIxed by #1138. May change results of tests that were subject to the bug
• In DC, the slackDistributionFailureBehavior parameter is now honoured [#1146]. Previously the behaviour was always LEAVE_ON_SLACK_BUS even if the parameter had a different value. Tests with a different value than LEAVE_ON_SLACK_BUS and a slack distribution failure condition may behave differently with this release.

Advanced API

• An extension API is provided to allow external AC Solvers in addition to the existing NewtonRaphson and NewtonKrylov solvers (#1107). The acSolverType has evolved to support other AC solvers available in the classpath.
• The utility class com.powsybl.openloadflow.util.MatrixUtil has been removed and the utility functions added to the com.powsybl.math.matrix.DenseMatrix class from powsybl-core [#1136]. This may break code of projets that took advantage of this internal utility class.