Combined Heat and Power Plant Model

This page documents the functionality of the CHP Model (combined heat and power plant model) available in SIMONA. This model is part of the SIMONA simulation framework and represented by an agent. In the current model, it is feasible to simulate nano- and micro-CHP units. As it is a cross-sector agent heat/electricity) the usage of a house-heat-model is mandatory. In the following, the CHP unit model and its controller unit is described. The controller unit is necessary to ensure, that different kinds of heat models can be applied.

Assumptions

The CHP unit is able to operate either at full load or not at all. Uncovered heat demand of former time-steps is not considered in the following steps, as the CHP unit does not posses a memory. Losses of the heat storage are not considered.

Parameters

Attributes, Units and Remarks

Please refer to PowerSystemDataModel - CHP Model for Attributes and Units used in this Model.

Implemented Behaviour

  • Agent Objectives The objective of the CHP agent is to cover the given heat demand in each time-step.

  • Storage medium This model can be implemented with any mutable storage (meaning that the storage requires the trait MutableStorage). The CHP unit is able to store/take energy, while the underlying storage medium performs the calculations for these operation.

The implemented behaviour is shown in the program sequence plan below. In general, the unit will turn on, if the energy in the storage is too low to satisfy the given heat demand and will turn off if the storage is completely filled. During operation, the CHP unit operates at full utilization.

Implementation:

Mathematical concept

The implementation of the CHP unit’s behavior is based on the following mathematical model.

Variable

Remarks

c(t)

indicates if the CHP unit is running or not

I

interval of two time steps (t-1, t]

td(t)

time of a single time step

WD(t)

heat demand

Wchp,n(t)

rated heat production

Wst(t)

storage level of the storage medium given by energy

Wst,min

minimum storage level of the storage medium given by energy

Wst,max

maximum storage level of the storage medium given by energy

Wges(t)

Wchp,n(t) + Wst(t)

deltaWD(t)

WD(t) - Wchp,n(t)

Qth,chp,n(t)

rated heat flow produced by the CHP

Pchp,n(t)

rated active power production

Pgen(t)

generated active power

Qgen(t)

generated reactive power

Given a time interval I, the heat demand WD(t-1), the running status c(t-1) and the storage energy level Wst(t-1) the CHP model calculates if the heat demand can be covered and if the CHP unit has to be turned off/on.