Summary of Smart Grid Software Modelling

A comprehensive review of the current state of the art in integrated building energy analysis tools has been carried out and it is apparent that a number of the tools have at least some of the capabilities that will be required of simulation tools to model domestic smart grid technologies. To compare the capabilities of the packages that have been described and to identify any areas in which improvement is needed, a standard set of criteria have been developed. These criteria will focus heavily on the abilities that will be required to model new domestic smart grid technology within buildings, rather than to accurately model the buildings themselves. The criteria which are described below have been selected with careful consideration given to the review of smart grid technology carried out in section 2.1.

Core Features

 Individual appliance modelling – Simulations should be able to model down to the individual appliance level as smart grid control strategies may rely on controlling smart appliances to manage demand. In this case, the characteristics of each individual appliance are important in dictating the ways in which the appliance can respond to control signals.

 Basic “lumped” models – As well as advanced individual appliance models, it may also be desired to lump the behaviour of a number of appliances into one simplified block.

 Closely coupled electricity, heat transfer and communications – Every element within a simulation should be able to interact with electricity, heat transfer and communications simulations concurrently. This capability will be important in

modelling smart electrical appliances which may also have some thermal mass or thermal output to their environment.

 Advanced software control of device behaviour – The ability to script the properties of devices will allow more accurate modelling of their behaviour than a mathematical model and will allow the implementation of “smart” control strategies which communicate with other elements in the simulation.

 Rapid development – Packages should support rapid definition of models to aid in the process of prototyping different strategies.

 Minimal constraints on system type – There should be no constraints on the type or scale of the system being modelled. When modelling smart grid technologies it may sometimes be necessary to model a whole building or community or a small number of interacting buildings. In contrast there may also be situations in which modelling is focussed on developing an individual piece of control equipment.

 Wide simulation time-step range – Detailed simulations of control systems such as maximum power point trackers for renewable energy systems or battery management systems may require microsecond resolution whereas whole building systems may require only hourly, daily or seasonal simulation. Packages should accommodate this by offering simulation time-steps in the range of microseconds to months.

Environment

 Weather – The package should support the modelling of the effect of weather on buildings and their systems.

 Importing weather data – To assist with the modelling of climate, packages should be able to import weather data.

Electricity Modelling

 AC and DC Systems – Renewable energy sources and storage devices primarily utilise DC while domestic power systems are primarily AC and therefore both types of system and the conversion between each should be supported.

 Renewable Generation – As explained in section 2.1.3 of this review, distributed renewable generation including CHP systems will be a core feature in future climate policies and therefore its inclusion in modelling domestic smart grid systems is crucial.

 Grid Connections – The assessment of import from and export to the electricity grid will be important in studying demand management algorithms. A grid connection and metering capabilities are therefore required.

 Electrical Storage – Electrical storage systems will be important for both demand management and smoothing the intermittency of local renewable sources.

Thermal Modelling

 Building Envelope – A building’s construction plays a key role in its energy usage and therefore should feature in a smart grid modelling package.

 Heat Conduction – Heat conduction between spaces is an essential part of the building envelope modelling capability.

 Infiltration and Natural Ventilation – Should also be an integral part of the building envelope modelling capability.

 Heating and Cooling Systems – Modelling of both the central plant (e.g. boilers) and heating elements (e.g. radiators) which perform conversion of energy to produce heat.

Communication

 Internal Communication – Support for communication between appliances and control systems within the building is required to model entities such as smart appliances.

 External Communication – Support for communication with the utility company is required to model smart metering systems and dynamic pricing tariffs.

The above set of criteria are not exhaustive but serve as a basic set of requirements for a domestic smart grid modelling package from which further requirements can be drawn. They do, however, serve as a useful standard set of test criteria for performing an at-a-glance comparison of the available features in the packages that were studied in sections 2.2.1 and

2.2.2. Table 2-1 shows this comparison and was developed from research carried out in preparing this literature review and through existing comparison tables available in [48].

Table 2-1: Comparison of the domestic smart grid modelling capabilities of whole-building energy analysis tools. A solid dot indicates that the package fully supports

the specified feature, a hollow dot indicates partial support and no dot indicates no support.

1 Rather than using mathematical models, the application is capable of modelling systems through scripting or other means to allow for greater degrees of detail in component implementations and communication between components within a system.

2 The application provides a graphical method of constructing models.

3 The application is not constrained to building modelling; it can model multiple buildings or individual building systems.

4 The application is capable of assessing both transient effects along with hourly, monthly or seasonal effects.

5 The application can import weather data in a non-proprietary format.