Release 1.2.0

lightsim2grid 1.2.0

This release adds a light environment: a grid2op-like reset / step loop that runs entirely
in C++. It also lets ScenarioSweep apply one topological action per row while keeping a
single symbolic factorization. OpenLoadFlow's bounded distributed-slack redistribution is now
available on the grid and on the batch algorithms. The physical checks now also report the
decisions OpenLoadFlow's outer loops would revisit. Many fixes come with it, mostly in the DC
batch path and in contingencies that split the grid.

Highlights

• Light environment: lightsim2grid.lightEnv.LightEnv is a (very) limited grid2op
  environment. It replays a time series of injections, plays registered topological actions
  (init_actions, then step(act_id)) with grid2op-like cooldowns and protections, and
  returns LightEnvObservation, read-only views with no copy. It can be copied cheaply, which
  is what a tree or beam search needs. It is header-only C++ (src/core/light_env/) and is
  also usable without python. It is new and its interface may still change. See
  docs/light_env.rst and benchmarks/light_env.py.
• Topological actions in ScenarioSweep: set_topo_actions gives each row its own
  topological action: disconnections, reconnections, or a bus split or merged. The whole batch
  still runs on one symbolic analysis. Batch results follow each row's action. A few cases are
  still refused; they are listed in the changelog.
• Bounded slack redistribution, OpenLoadFlow style: LSGrid.redistribute_active_power
  shares a known imbalance across the units of the distributed slack. It respects their
  [min_p, max_p] bounds and never changes the sign of a unit's injection.
  ContingencyAnalysis / ScenarioSweep gain redistribute_slack, which redistributes the
  power a row loses (a generator contingency or an island) before solving.
  LSGrid.cap_slack_at_active_limits applies OpenLoadFlow's slack rule to a solved grid.
• Richer batch results: compute_branch_results() gives P and Q at both ends of every
  branch, per row. compute_gen_results() / get_gen_nd Q per row, by the same rules as LSGrid. Also new: get_rb_iter(), get_Ybus(row)/get_dcYbus(row), and LSGrid.get
• Violation checks on the grid itself: LSGrid.get LSGrid.get_physical_violations()run the batch cheac_pf/dc_pf`.
• New physical checks: these report what an OpenLoadFlow outer loop would change. They
  cover a PQ unit that would regulate again (generators, SVCs and VSC stations:
  LOW_VOLTAGE_AT_MIN_Q / HIGH_VOLTAGE_AT_MAX_Q), amaton would
  switch it on, a remote voltage control held from an unrealistic voltage, and an hvdc line
  frozen at its AC-emulation limit. bake_outer_loops returns what it froze, and
  init_from_pypowsybl flags it. They are reported, n
• KLU by default: the init_from_* loaders select NR_KLU / DC_KLU when KLU is compiled
  in (previously NR_SparseLU / DC_SparseLU).

Breaking changes

• BINARY_FORMAT_VERSION goes from 10 to 18. Generatoerter
  stations, hvdc lines and the grid carry new state, so files saved with 1.1.0 no longer load
  and must be re-exported.
• LSGrid.consider_only_main_component() now redistri takes out
  by default, and returns a SlackRedistributionReport. Pass redistribute_slack=False for
  the previous behaviour. The grid2op backend and `inis it.
• LSGrid.get_Ybus_solver() / get_dcYbus_solver() return a read-only view instead of a copy.
  It stays valid until a powerflow rebuilds the matrixor to pass
  it to compute_pf.
• Operational limit checks now ignore a value that sit
  violation_rel_tol (default 1e-9). Before, the last bit of rounding decided.
• (C++ / plugins) BaseAlgo gains the virtual distri set_voltage_control_v_setnow takes anEigen::Refd their
  overrides updated.

Fixes

DC batch algorithms

• A threaded DC ContingencyAnalysis / ScenarioSweep (nb_thread > 1) no longer segfaults.
• A row that edits no admittance, right after one thatthe previous
  row's matrix.
• Phase-shifter flows had the wrong sign and no `sn_mvase shifter
  also kept its shift injections.
• With handle_disconnected_grid, rows no longer use
• Disconnecting a half-open branch no longer edits Bbus. A bus whose regulating generators are
  disconnected no longer keeps their setpoint as its m
• get_error() reports NoError after a converged `d

**Contingencies that split the grid (`handle_disconnec

• The reference slack bus was chosen with grid and soland the
  choice never reached the solver. A reference forced ` is no
  longer lost.
• A contingency that strands every controller of a mul group no
  longer diverges. One that strands the bus a group regulates is skipped (NOT_SIMULATED)
  instead of running every iteration.
• Stranded HVDC converter stations now count in the power an islanding takes out.
• consider_only_main_component left stranded units ihe next
  powerflow raised "One of the slack bus is disconnect
• ContingencyAnalysis: changing handle_disconnected after a
  computation returned the previous results.

ScenarioSweep

• set_contingency_gens no longer turns a bus PQ when a voltage-regulating storage unit still
  holds it.
• With modify_gen_v, a disconnected generator no lonpoint of the
  generators left on its bus.

**OpenLoadFlow comparison (bake_outer_loops / `init_

• Closer agreement on reactive-limit freezing, the SVC its b0),
  hvdc operator active power ranges, VSC capability curves, and units dispatched at their
  active limits.

Misc

• LSGrid pickling no longer breaks the build on MSVCy with gcc 8.
• The light environment's protections no longer loop fonnection,
  and the reward is no longer an integer division.

Performance

• LSGrid.get_Ybus(), get_dcYbus() and get_Bf() rne pass
  instead of re-sorting it.
• The sparse matrices returned by the getters (includi reach
  python without a copy.
• bake_outer_loops and init_from_pypowsybl are muccially grids
  with batteries. Results are unchanged.

Other additions

• LSGrid.set_keep_vinit_at_group_controlled_buses an`.
• Docs: the light environment, reusing one `ScenarioSwreads vs
  processes.
• Design notes on outer loops and control limits under
  (docs/dev_notes/).

The full list is in CHANGELOG.rst.