Load Gradient of BMModel should consider time delta between tick and last tick

[danielfeismann]

Currently the BMModel implicitly considers time steps of one hour for applying the loadGradient.

private def applyLoadGradient(
      pEl: ComparableQuantity[Power]
  ): ComparableQuantity[Power] = {
    _lastPower match {
      case None => pEl
      case Some(lastPowerVal) =>
        val pElDeltaMaxAbs = sRated
          .multiply(loadGradient)
          .multiply(Quantities.getQuantity(1d, HOUR))
          .multiply(cosPhi)
          .asType(classOf[Power])

        pEl.subtract(lastPowerVal) match {
          case pElDelta if pElDelta.isGreaterThan(pElDeltaMaxAbs) =>
            lastPowerVal.add(pElDeltaMaxAbs)
          case pElDelta if pElDelta.isLessThan(pElDeltaMaxAbs.multiply(-1)) =>
            lastPowerVal.subtract(pElDeltaMaxAbs)
          case _ =>
            pEl
        }
    }
  }
}

to do:

• [ ] check intended behaviour of BM plant
• [ ] adapt methods to consider tick and last tick
• [ ] Use PowerRamp when changed to squants in meantime