Machine learning & Kafka KSQL stream processing — bug me when I’ve left the heater on

What on earth is this?

Household power consumption fluctuates throughout the day. However, the pattern of electricity use follows a typical curve and becomes predictable after sufficient observations. Would it surprise you that very little power is used at night when everyone is asleep? Probably not — but a sudden sudden surge of power used 4 am this is worth checking via an alert on my phone

I’m bored — can I get a video?


Real-time power usage monitoring

Training and Data Capture

With 3 months of data from my experiment of Home Power Monitoring using a Raspberry Pi I had a stack of data to determine what our household power consumption looked like throughout the average day.

Expected range (green) of power consumption by time of day for the month of August
Anomaly score based on hour and power usage. Values above 1.0 are unusual

User Defined Function — and KSQL

KSQL is an open source, streaming SQL engine that enables real-time data processing against Apache Kafka. KSQL supports creating User Defined Scalar Functions (UDFs) via custom jars that are uploaded to the ext/ directory of the KSQL installation. That is, my compiled anomaly score function can be exposed to the KSQL server — and executed against the Kafka stream

ksql> list functions; Function Name           | Type
. . .
ANOMOLY_POWER | SCALAR <--- I need this one
create stream raw_power_stream with (kafka_topic='raw_power', value_format='avro');

create stream power_stream_rekeyed as \
select rowtime, hour, kwh, anomoly_power(hour, kwh) as fn \
from raw_power_stream partition by rowtime;

create stream anomoly_power with (value_format='JSON') as \
select rowtime as event_ts, hour, kwh, fn \
from power_stream_rekeyed where fn>1.0;

Ringing the Alarm

The continuous real-time stream processing is fairly useless unless we have a way of raising an alarm when something odd has happened. I wanted notifications to appear on both my mobile phone and be announced over our Google Home smart speaker. Why get bothered only once when I can get annoyed twice?

Mobile Device notification via Pushbullet

Pushbullet is an awesome service bridge that provide a simple API for sending push-notifications to iOS and Android devices.

An iOS push-notification via push-bullet

Google Home Text-to-Speech (TTS) via Home Assistant

I run the Home Assistant software locally to control home automation tasks. One nice feature is a simple API to send text messages as spoken voice commands directly to out Google Home smart speaker. That is, construct a string — and it gets spoken (quite loudly) via the Google Home.

What did I learn?

The first legitimate alarm I received was when I was on holiday. The notification at 9am on a Saturday morning was an notification signifying the household was using substantially less power than was expected. This was indeed true — maybe I need more holidays to train the model correctly!

Ready To Try

The entire project simply requires docker to run locally.

Credits & References



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Simon Aubury

Simon Aubury

Day job: data steaming & system architecture. Night gig: IoT and random project hacking