Heat Load Prediction and Energy Systems Optimization

The PRESS (Prognosis and Energy Control System, Danish: Prognose- og EnergiStyrings-System) is a suite of systems used for load forecasting, temperature control, and optimization of district heating systems. PRESS can be used in many different ways depending upon your main focus. Some installations use PRESS for on-line forecasts of the heat load, whereas other installations are using PRESS for an automatic control of the supply temperature. Also a total optimization of the heat production can be embedded in the PRESS system.

History​

The development of PRESS started in 1988. The original idea, as proposed by some district heating companies, was to used the data already available in most district heating systems for on-line forecasting, temperature control and optimization. In many years the system was mostly developed for supporting research on heat load forecasting and optimal temperature control, but since late 90'ties the system has been used operationally by a increasing number of district heating systems.​​

Input to PRESS

Depending on the configuration of PRESS the following data is taking into account

  • Online measurements of heat load
  • Supply and return temperature
  • Water flow at the production plants
  • Temperature measurements from the district heating network
  • Local measurements of ambient air temperature, wind speed, solar radiation, etc.
  • Meteorological forecasts of the local air temperature, wind speed, etc. for horizons up to the desired operational horizon, typically one week.

Local climate measurements are optional, if not available the system used meteorological forecast data instead.

For optimization purposes the system furthermore use input from the operators. E.g. for optimization of the supplytemperature the required supply temperature at the customers must be specified, see e.g. the following presentation

Besides these data PRESS automatically takes into account the systematic behavior of the consumers heat consumption. Also the heat stored in the distribution network is taken into account.​

Output from PRESS​

Depending on the configuration of PRESS the following output is supplied

  • Heat load forecasts
  • Set points / schedules for supply temperature or production
  • Diagnostics regarding plant operation

The forecasts are supplied together with standard uncertainty intervals. For longer forecast horizons where the meteorological forecast uncertainty may be significant the standard forecasts can be supplemented with quantile forecasts, which are highly reliable representations of the uncertainty.

In order to include the development over time in the representation of uncertainty reliable load scenarios can further supplement the standard forecasts. These scenarios can furthermore be generated jointly with other ENFOR scenarios as e.g. power load or wind power production scenarios. In this way all relevant auto- and cross-correlations can be accounted for.​

Methods underlying PRESS​

PRESS is built on artificial intelligence, and hence the system automatically calibrates to the actual situation. For instance the models for forecasting the heat load automatically takes into account changes in the number of customers connected, or changes in the user profiles, and the models for automatic supply temperature control and optimization adapts automatically to changes in the district heating network. Hence, for operation of PRESS, there is no need to maintain a detailed database describing the district heating network.

For further technical details about, including some examples of the benefits from using PRESS we refer to the section for technical papers or the following presentation.​

Modules in PRESS​

The PRESS suite consists of a number of modules:

  • PRESS-Base: On-line data collection and validation
  • PRESS-Prognosis: On-line heat load forecasting
  • PRESS-TO: On-line network temperature optimization
  • PRESS-PO: On-line production optimization
  • PRESS-OP: On-line statistics summarizing the operation of the district heating system

PRESS-Base: Data collection and validation​

Since PRESS is an on-line system, the data collection and validation module is needed in all cases. The module collects the necessary data, detects possible errors in the data, and validate the data for the on-line application in the subsequent modules.​

PRESS-Prognosis: On-line heat load forecasting​

The heat load forecasting is based on meteorological forecasts of primarily ambient air temperature, but the system is also able to use forecasts of radiation and wind speed, if available. The system forecasts the hourly heat load for horizons up to the maximal horizon for which meteorological forecasts are available.

One of the aspects complicating heat load forecasting is the fact that the heat dynamics of the buildings seriously affect the heat demand on an hourly basis. The PRESS system automatically takes this smoothing effect into account. Furthermore, the system continuously adapts to the actual situation by continuously monitoring the consumption. In this way the systems automatically adapts to things such as

  • Changes in consumer behaviour
  • Changes in the number of consumers
  • Changes in the meteorological models
  • Changes in the thermal characteristics of the buildings
  • Changes in the network

PRESS-TO: On-line network temperature optimization​

To reduce heat loss in the distribution network the temperature in the district heating network should be kept low while at the same time keeping the temperature sufficiently high at the consumers and respecting pumping costs.

The online network temperature optimization module achieves this goal by monitoring the temperature at a number of critical points in the network and respecting the pumping costs using the heat load forecasts.

The controller used is very advanced in several aspects, e.g. it is able to handle the time-varying delay from supply point to the critical points and it continuously adapts to system changes.

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PRESS-PO: On-line production optimization​

This module is typically tailored to the individual district heating system / production facilities because large district heating networks often experience some differences in cost structure. For standard production optimization problems a web-service solution is available. In this case the production system considered must consist of one or more production units (CHP units, boilers, electrical boilers / heat pumps) and a heat storage facility. Based on fuel costs and electricity prices and heat load forecasts the system is then able to determine the optimal production schedule for the coming day.

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PRESS-OP: On-line statistics​

Using consumption and temperature data this module continuously gathers information about the characteristics of the system and presents this in a comprehensive form. This information includes

  • Duration curve of the consumption
  • The energy signature, i.e. the expected consumption as a function of air temperature
  • The diurnal variation of the consumption.

In this way the persons operating the system can easily monitor the system and take action if undesirable changes occur.​

​Contact information

​ENFOR A/S

Lyngsø Allé 3

DK-2970 Hørsholm

​​Phone: (+45) 45 350 350

E-mail: info@enfor.dk

VAT no.: 29421633

ENFOR A/S
Lyngsø Allé 3, 2970 Hørsholm
Tlf.: 45 350 350
info@enfor.dk