On the design of 5GDHC substation control systems

ABSTRACTThis paper presents challenges in the control of 5GDHC networks and proposes an approach for the robust control design of these networks. Temperatures are low and temperature differences are small in 5GDHC networks, in order to minimise heat losses in the distribution network and directly utilise low-temperature heat sources. Therefore, the robust control design of substations is crucial for stable and efficient operation of 5GDHC networks. We proposed the key steps to obtain a consistent control design that can be verified and tested prior to commissioning of the building substations and network. The design approach was elaborated in a case study in an existing neighbourhood in Haarlem, the Netherlands, constructed in the 1930s to 1970s. This neighbourhood will become independent of natural gas using PVT-rooftop panels, individual heat pumps (HP), a 2-pipe, bi-directional energy flow network operating at ultra-low temperatures and ATES system as a seasonal and daily storage facility

Categorization of trapezoidal open channels based on flow conditions for the choice of simple models

Many applications in water management rely on keeping the water levels of an open water channel within given bounds, e.g. irrigation canals, drainage systems, and hydropower systems. These are all open water channels where the water level is influenced by several known and unknown factors like precipitation, operation of structures, etc. Water levels can be efficiently controlled by model predictive control (MPC). In MPC the optimization algorithms give advice at every time step based on the current state of the system as well as on the expected future state. These algorithms need a model to predict the response of the system to the control inputs. In most cases, the need to guarantee convexity of the optimization problem leads to the requirement that these models should be linear. To date, several such linear models are available in literature, which are suited for control purposes. However, the choice between these models is not straightforward. In this work, we extend a categorization of open channels, based on which the choice of a simple model can be advised

Closed-loop model predictive control with mixed-integer optimization of a river reach with weirs

A decision support system for water management based on convex optimization, is applied to a water system containing river branches connected by weirs. This paper describes a convex approximation approach for the model predictive control of weirs implemented using RTC-Tools 2. Model predictive control using RTC-Tools 2 is implemented for a river that contains 12 river reaches divided by controllable weirs and it is tested in closed loop simulation with a non-linear model. By controlling the weir heights, it is shown how the discharge wave is dispatched in the river without the water levels exceeding the bounds

Strengths, weaknesses, opportunities and threats of demand response in district heating and cooling systems. From passive customers to valuable assets

Buildings can deliver short-term thermal energy storage by utilising the thermal capacity of the building construction and/or by activating the water tanks included in the heating/cooling installation. The flexibility potential of demand management using decentralized thermal energy storage has been quantified in many theoretical modelling studies, and it is considered an essential technology for an affordable energy transition. We have investigated the drivers and barriers to the adoption of demand management in buildings in district heating and cooling systems via a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis and presented 17 elements that shape the current and future application of this concept. The results indicate that the application of the DR concept has left the theoretical studies and moved towards real-life applications. Yet, there is a lack of feasible business models and regulatory frameworks supporting the large-scale application of the concept. Utilities and their customers do not fully understand the benefits of the DR concept; therefore they are reluctant to adopt it outside of the research projects where the test environment is fully controlled and with limited impact and timeline. Therefore, the regulatory framework must be adjusted to allow DHC operators to develop new business models and DR tariffs that will incentivise the customers to deliver flexibility to the system without compromising their comfort and everyday practices and increasing energy poverty.</p