PowerStudio 1.2.0

PowerStudio 1.2 adds a fifth study, electromagnetic transients, and makes the results and the app easier to read and
to learn.

Electromagnetic transients. The EMT simulation (Calculate tab, Alt+W) follows the three phase voltages and
currents of the network over its first cycles at a microsecond step, where the stability simulation follows the
machines' swings over seconds. Lines longer than a step's travel are travelling waves, the others coupled π sections;
transformers are windings connected by their vector group, with any extra phase shift; machines and external grids are
EMFs behind their short-circuit impedance. Its events are three-phase, line-to-line, two-phase-to-earth and
line-to-earth faults through a resistance, their clearing, and breakers that trip or close; each pole of a breaker,
and each phase of a fault, goes out at its own current zero. Lines, cables, transformers, loads and capacitor banks out
of service can be switched in. The EMT tab shows the waveforms with a time zoom and per-phase switches, the peaks and one-cycle
RMS values of every busbar, branch, source and fault, every pole that opened, and exports CSV. Both samples come with
EMT events. The engine agrees with ngspice on five fault and switching cases, on both samples and a 100 km line, its
voltages to within 2.1e-3 of crest, natively and in WebAssembly. It is a first slice (docs/design/EMT.md): sources
keep their EMF, so a run stands for the first cycles, and there are no machine or converter controls, saturation or
arresters. It is not a compliance tool for any EMT standard or grid code.

Charts. The busbar and branch results of a load flow, the busbars of a short circuit and the branches of a
contingency analysis can be shown as a chart instead of a table: the voltage profile around 1 p.u. with each busbar's
band, the loading of each branch against 90 % and 100 %, Ik″ at every busbar and the worst loading under N-1 against
its limit. A chart shows the table's own rows, filtered and ordered as the table is, and a recorded run being compared
appears across each bar. Click a bar, or move along the bars with the keyboard, to select its element. On a grid of
tens of thousands of elements each pixel column shows its most extreme element, so peaks and dips stay visible.

Guide. One task-based guide (Help tab, "Getting started" and "Guide", published at /guide/ on the website) replaces
the old getting-started, user-guide and benchmark-kit pages. It has a first session on the IEEE 14-bus sample that
covers load flow, charts, winter and summer study cases, short circuit, N-1, stability, EMT, and exporting and
comparing results, then a chapter for each study and for comparing PowerStudio with your own tool. Browser tests
follow the chapters step by step, so the guide and the app stay in step.

Also fixed. The stability plot's read-out now escapes element names before showing them. In the EMT simulation
before release: a close sent while a tripped breaker waited for its current zeros cancels the trip, and a load
switched in takes the study case's load scaling like the loads in service.

Documents saved by 1.1, 1.0 and 0.1 open unchanged and solve as they did.

Files

• PowerStudio.html: the app. Open it in a browser; it needs no installation or network.
• PowerStudio.html.sha256: its checksum. Check it with shasum -a 256 -c PowerStudio.html.sha256, and the build's
  provenance with gh attestation verify PowerStudio.html --repo swiftugandan/powerstudio.
• PowerStudio.cdx.json: the software bill of materials.

docs/guide/ shows how to use the app, including the EMT simulation and charts, and docs/design/EMT.md describes the
design of the EMT simulation.