---
title: Power-based mode
mode: powerBased
tier: 2
status: placeholder
updated: 2026-04-22
---

# Power-based mode — *Tier 2 template*

> **Status — not yet implemented.** Placeholder. This page documents the intended shape of a grid-aware / netcongestion-aware station.

## At a glance

| Item | Value |
|---|---|
| Tier | 2 — parameterised transfer function |
| Signal driving demand | basin level (primary), **max-power budget** (clip) |
| Secondary inputs | measured pump power, live grid-price / peak-hours signal |
| Output | demand 0–100 % clipped so `Σ pump power ≤ maxPowerKW(t)` |
| Thresholds adjusted at runtime? | `maxPowerKW(t)` yes — level thresholds no |
| Use when | Grid has peak-hour tariffs or net-congestion caps |

## Diagram — the levelbased curve with a moving clip ceiling

```
demand %                                     ← dashed line: levelbased curve
 100 ┤               ╱ ───────                ← solid: clip at powerBudget(t)
     │              ╱            clip lowers
     │             ╱             during grid peak
     │            ╱       ─────────
     │           ╱       ╱
     │          ╱       ╱
     │         ╱       ╱
  0  ┼────────●───────●─────────────────────► level
             startLevel    maxLevel

         ↑ the family of curves:
           clip=100% (grid idle),
           clip=70% (shoulder),
           clip=40% (peak).
```

The *shape* stays levelbased; the *ceiling* drops when the grid is strained. That's the Tier-2 signature: same input axis, parameter shifts the curve.

## Inputs

| Signal | Where from | Role |
|---|---|---|
| current level | as in levelbased | primary input |
| `config.control.powerBased.maxPowerKW` | editor, static | hard cap on station power |
| `config.control.powerBased.powerControlMode` | `limit` / `optimize` | whether to just clip or to schedule |
| live grid signal (future) | external topic or forecast | modulates the cap over time |
| measured pump power | `power.measured.*` from children | real-time feedback against the cap |

## Threshold policy

Level thresholds (`minLevel`, `startLevel`, `maxLevel`) are **identical to levelbased** — they define the shape of the underlying curve. What's new is a runtime-varying ceiling `demandCap(t)` derived from the power budget.

`demandCap(t) = 100 × (maxPowerKW(t) / nominalStationPowerAtFull)` — where `maxPowerKW(t)` may come from config (static `limit` mode) or an external grid-price feed (dynamic).

## Demand formula

```text
rawDemand = levelbasedDemand(level)          # the underlying Tier-1 curve
demandCap = min(100, 100 × maxPowerKW(t) / nominalStationPower)
demand    = min(rawDemand, demandCap)
```

When `demandCap < rawDemand`, the mode sacrifices drainage rate to stay within power budget. Level may rise — the high-volume safety layer still applies as the last line of defence before physical overflow.

## Edge cases

- **Peak hour with rising level.** demandCap drops faster than level rises → demand gets clipped; level approaches `overflowLevel`. If high-volume safety trips, it overrides the clip (safety wins).
- **Power signal dropout.** Fall back to static `maxPowerKW` from config; log warning.
- **Grid exit from peak while basin is nearly full.** demandCap jumps back to 100; PID is memoryless so demand rises in one tick to match rawDemand.
- **Measured vs predicted pump power.** Cap is enforced on predicted (decisions are made before the pump responds). Reconcile against measured for logging/diagnostics.

## Related

- [Functional description](../functional-description.md)
- [modes/levelbased.md](levelbased.md) — Tier 1 reference (the curve that powerBased clips)
- [modes/flowbased.md](flowbased.md) — other Tier-2 example with different control variable