Open Energy Monitor
There are three key areas of interest within Open Energy Monitor regarding control: Emoncms - the West Whins monitoring hub; Node-RED – the West Whins system’s control tool; and Demand Shaper - a module in development used for shaping the time of energy use.
Emoncms
The OpenEnergyMonitor (OEM) project provides open source monitoring for understanding energy, particularly focusing on the integration of renewables. Emoncms is an open-source web-app within OEM that designs and visualizes real time data for local demand or the production of energy.
As part of the OpenEnergyMonitor kit, Emoncms needs hardware to collect data. This is the purpose of the elements shown in Figure 1. The EmonTx is a sensor that provides a voltage signal for full real power calculations and AC VRMS readings. The EmonTH is a sensor that provides the room temperature and humidity. These sensors can be connected wirelessly to an EmonPi - a web-connected, open-hardware, Raspberry Pi and Arduino-based electricity and environment monitoring unit. Thus, sensors other than the ones described in Figure 1 can be connected. An EmonBase can also be used to receive the data from the sensors and then send it locally or remotely to Emoncms.
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Figure 1: Emoncms hardware
(Source: OpenEnergyMonitor.org)
Emoncms has a remote version, available in the resources section. The user only needs to create an account to be able to link with an EmonPi and read the local data directly through the app. However, this version does not allow modification of code, which means that it is above all for reading only. If the user wants to write code, for example to implement smart controls on an EmonPi, it is possible to directly download Emoncms on windows or linux. With this local version, the user is able to install specific modules and integrate their own code.
Node-RED
Node-RED acts as a central control hub for the hardware, APIs and other services available within Open Energy Monitor. It is a user-friendly visual editor where inputs, functions and outputs can be defined and connected. For example, the West Whins M-Bus data has been filtered via Python scripts such that the data can be read into Emoncms - all via Node-RED. The practical difficulties of using Node-RED as a means of integrating smart logic control within a real system, include the requirement of access to the local version of Emoncms feeds and its integrated Node-RED data, and the lack of research detailing how a Node-RED output could interact with the real system. For these reasons, this project’s approach to smart control integration has focussed on a theoretical design .
Demand Shaper
The Demand Shaper Module is an interesting development that uses APIs and a user defined input to balance energy demand from the grid. The significance of this module in relation to smart control is its ability to schedule charging periods based on a wide range of forecasting information.
Figure 2 demonstrates the range of APIs available within this module that can be considered when calculating the best time to run the load. This is accompanied with user defined inputs specifying how long the system needs to be charged for and the time it needs to be completed by. At this stage, these controls are relatively simplistic and can only be recommended for the smart logic of on-site EV charging. However, it is anticipated that future versions of this module will support smart logic control of heat pumps and presents itself as a development worth following. The module is available in the download section.
Figure 2: Demand Shaper Module