Smart Charging with Web of Things

Simulation of a photovoltaic system (based on MQTT) and an electric car (based on HTTP) to demonstrate a smart charging scenario based on the W3C Web of Things approach.

	Sun-Inverter	eCar
Protocol	MQTT	HTTP
Content-type	text-plain	application-json
Data model / functions	status ("powerOn”, "powerOff”, "error”) Topic (publish): {..}/status	status ("readyToCharge”, "charging”, "stopCharging”) Resource (GET): {..}/state
	power (0..7500 Watt) Topic (publish): {..}/power	soc (0..100%) Resource (GET): {..}/soc
		startCharging Resource (POST): {..}/startCharging
		stopCharging Resource (POST): {..}/stopCharging

Prerequisites

• NodeJS version 10+
• MQTT broker (e.g., Eclipse Mosquitto)

Install dependencies (Eclipse node-wot)

• npm install @node-wot/core@0.7.7
• npm install @node-wot/binding-http@0.7.7
• npm install @node-wot/binding-mqtt@0.7.7
• npm install @node-wot/binding-file@0.7.7

Run Application

• start PV simulation in terminal I: node pv-system.js <MQTT_Broker_Address:Port> (e.g.,node pv-system.js 127.0.0.1:1883)
• start eCar simulation in terminal II: node ecar.js
• start smart charging application in terminal III: node smart-charging.js

Note: The PV and eCar simulations automatically expose their Thing Descriptions. This simple application stops when the eCar is fully charged.