Posting data
The platform FlexMeasures strives on the data you feed it. Let’s demonstrate how you can get data into FlexMeasures using the API. This is where FlexMeasures gets connected to your system as a smart backend and helps you build smart energy services.
We will show how to use the API endpoints for POSTing data. You can call these at regular intervals (through scheduled scripts in your system, for example), so that FlexMeasures always has recent data to work with. Of course, these endpoints can also be used to load historic data into FlexMeasures, so that the forecasting models have access to enough data history.
Note
For the purposes of forecasting and scheduling, it is often advisable to use a less fine-grained resolution than most metering services keep. For example, while such services might measure every ten seconds, FlexMeasures will usually do its job no less effective if you feed it data with a resolution of five minutes. This will also make the data integration much easier. Keep in mind that many data sources like weather forecasting or markets can have data resolutions of an hour, anyway.
Table of contents
Prerequisites
FlexMeasures needs some structural meta data for data to be understood. For example, for adding weather data we need to define a weather sensor, and what kind of weather sensors there are. You also need a user account. If you host FlexMeasures yourself, you need to add this info first. Head over to Getting started, where these steps are covered, or study our CLI Commands.
You should be familiar with where to find your API endpoints (see Main endpoint and API versions) and how to authenticate against the API (see Authentication).
Note
For deeper explanations of the data and the meta fields we’ll send here, You can always read the Introduction , e.g. Signs of power values, Resolutions, Setting the recording time and Units.
Note
To address assets and sensors, these tutorials assume entity addresses valid in the namespace fm0
. See Introduction for more explanations.
Posting weather data
Weather data (both observations and forecasts) can be posted to POST /api/v2_0/postWeatherData. The URL might look like this:
https://company.flexmeasures.io/api/<version>/postWeatherData
Weather data can be posted for the following three types of weather sensors:
“radiation” (with kW/m² as unit)
“temperature” (with °C as unit)
“wind_speed” (with m/s as unit)
The sensor type is part of the unique entity address for each sensor, together with the sensor’s latitude and longitude.
This “PostWeatherDataRequest” message posts temperature forecasts for 15-minute intervals between 3.00pm and 4.30pm for a weather sensor located at latitude 33.4843866 and longitude 126.477859. This sensor is located in Korea’s timezone ― we also reflect that in the datetimes.
The forecasts were made at noon, as the prior
field indicates.
{
"type": "PostWeatherDataRequest",
"sensor": "ea1.2018-06.io.flexmeasures.company:temperature:33.4843866:126.477859",
"values": [
20.04,
20.23,
20.41,
20.51,
20.55,
20.57
],
"start": "2015-01-01T15:00:00+09:00",
"duration": "PT1H30M",
"prior": "2015-01-01T12:00:00+09:00",
"unit": "°C"
}
Note how the resolution of the data comes out at 15 minutes when you divide the duration by the number of data points. If this resolution does not match the sensor’s resolution, FlexMeasures will try to upsample the data to make the match or, if that is not possible, complain.
Observations vs forecasts
To post an observation rather than a forecast, simply set the prior to the moment at which the observations were made, e.g. at “2015-01-01T16:30:00+09:00”. This denotes that the observation was made exactly after realisation of this list of temperature readings, i.e. at 4.30pm.
Alternatively, to indicate that each individual observation was made directly after the end of its 15-minute interval (i.e. at 3.15pm, 3.30pm and so on), set a horizon to “PT0H” instead of a prior.
Finally, delays in reading out sensor data can be simulated by setting the horizon field to a negative value. For example, a horizon of “-PT1H” would denote that each temperature reading was observed one hour after the fact (i.e. at 4.15pm, 4.30pm and so on).
See Setting the recording time for more information regarding the prior and horizon fields.
Collecting weather data from OpenWeatherMap
For convenience for organisations who host FlexMeasures themselves, we built in a CLI task which collects weather measurements and forecasts from the OpenWeatherMap API. You have to add your own token in the OPENWEATHERMAP_API_KEY setting first. Then you could run this task periodically, probably once per hour. Here is how:
flexmeasures add external-weather-forecasts --location 33.4366,126.5269 --store-in-db
Consult the --help
for this command to learn more about what you can do with it.
Posting price data
Price data (both observations and forecasts) can be posted to POST /api/v2_0/postPriceData. The URL might look like this:
https://company.flexmeasures.io/api/<version>/postPriceData
This example “PostPriceDataRequest” message posts prices for hourly intervals between midnight and midnight the next day
for the Korean Power Exchange (KPX) day-ahead auction.
The prior
indicates that the prices were published at 3pm on December 31st 2014 (i.e. the clearing time of the KPX day-ahead market, which is at 3 PM on the previous day ― see below for a deeper explanation).
{
"type": "PostPriceDataRequest",
"market": "ea1.2018-06.io.flexmeasures.company:kpx_da",
"values": [
52.37,
51.14,
49.09,
48.35,
48.47,
49.98,
58.7,
67.76,
69.21,
70.26,
70.46,
70,
70.7,
70.41,
70,
64.53,
65.92,
69.72,
70.51,
75.49,
70.35,
70.01,
66.98,
58.61
],
"start": "2015-01-01T00:00:00+09:00",
"duration": "PT24H",
"prior": "2014-12-03T15:00:00+09:00",
"unit": "KRW/kWh"
}
Observations vs forecasts
For markets, the time at which the market is cleared (i.e. when contracts are signed) determines the difference between an ex-post observation and an ex-ante forecast. For example, at the KPX day-ahead auction this is every day at 3pm. To post a forecast rather than an observation, simply increase the horizon. For example, a horizon of “PT57H” would denote a forecast of 24 hours ahead of clearing.
Posting power data
For power data, USEF specifies separate message types for observations and forecasts. Correspondingly, FlexMeasures uses separate endpoints to communicate these messages. Observations of power data can be posted to POST /api/v2_0/postMeterData. The URL might look like this:
https://company.flexmeasures.io/api/<version>/postMeterData
while forecasts of power data can be posted to POST /api/v2_0/postPrognosis. The URL might look like this:
https://company.flexmeasures.io/api/<version>/postPrognosis
For both endpoints, power data can be posted in various ways. The following examples assume that the endpoint for power data observations (i.e. meter data) is used.
Todo
For the time being, only one rate unit (MW) can be used to post power values.
Single value, single connection
A single average power value for a 15-minute time interval for a single connection, posted 5 minutes after realisation.
{
"type": "PostMeterDataRequest",
"connection": "ea1.2018-06.io.flexmeasures.company:1:1",
"value": 220,
"start": "2015-01-01T00:00:00+00:00",
"duration": "PT0H15M",
"horizon": "-PT5M",
"unit": "MW"
}
Multiple values, single connection
Multiple values (indicating a univariate timeseries) for 15-minute time intervals for a single connection, posted 5 minutes after each realisation.
{
"type": "PostMeterDataRequest",
"connection": "ea1.2018-06.io.flexmeasures.company:1:1",
"values": [
220,
210,
200
],
"start": "2015-01-01T00:00:00+00:00",
"duration": "PT0H45M",
"horizon": "-PT5M",
"unit": "MW"
}
Single identical value, multiple connections
Single identical value for a 15-minute time interval for two connections, posted 5 minutes after realisation. Please note that both connections consumed at 10 MW, i.e. the value does not represent the total of the two connections. We recommend to use this notation for zero values only.
{
"type": "PostMeterDataRequest",
"connections": [
"ea1.2018-06.io.flexmeasures.company:1:1",
"ea1.2018-06.io.flexmeasures.company:1:2"
],
"value": 10,
"start": "2015-01-01T00:00:00+00:00",
"duration": "PT0H15M",
"horizon": "-PT5M",
"unit": "MW"
}
Single different values, multiple connections
Single different values for a 15-minute time interval for two connections, posted 5 minutes after realisation.
{
"type": "PostMeterDataRequest",
"groups": [
{
"connection": "ea1.2018-06.io.flexmeasures.company:1:1",
"value": 220
},
{
"connection": "ea1.2018-06.io.flexmeasures.company:1:2",
"value": 300
}
],
"start": "2015-01-01T00:00:00+00:00",
"duration": "PT0H15M",
"horizon": "-PT5M",
"unit": "MW"
}
Multiple values, multiple connections
Multiple values (indicating a univariate timeseries) for 15-minute time intervals for two connections, posted 5 minutes after each realisation.
{
"type": "PostMeterDataRequest",
"groups": [
{
"connection": "ea1.2018-06.io.flexmeasures.company:1:1",
"values": [
220,
210,
200
]
},
{
"connection": "ea1.2018-06.io.flexmeasures.company:1:2",
"values": [
300,
303,
306
]
}
],
"start": "2015-01-01T00:00:00+00:00",
"duration": "PT0H45M",
"horizon": "-PT5M",
"unit": "MW"
}
Posting flexibility states
There is one more crucial kind of data that FlexMeasures needs to know about: What are the current states of flexible devices? For example, a battery has a state of charge.
The USEF framework defines a so-called “UDI-Event” (UDI stands for Universal Device Interface) to communicate settings for devices with Active Demand & Supply (ADS). Owners of such devices can post these states to POST /api/v2_0/postUdiEvent. The URL might look like this:
https://company.flexmeasures.io/api/<version>/postUdiEvent
This example posts a state of charge value for a battery device (asset 10 of owner 7) as UDI event 203. From this, FlexMeasures derives the energy flexibility this battery has in the near future.
{
"type": "PostUdiEventRequest",
"event": "ea1.2018-06.io.flexmeasures.company:7:10:203:soc",
"value": 12.1,
"datetime": "2015-06-02T10:00:00+00:00",
"unit": "kWh"
}
Note
At the moment, FlexMeasures only supports batteries and car chargers here (asset types “battery”, “one-way_evse” or “two-way_evse”). This will be expanded to flexible assets as needed.
Actually, UDI Events are more powerful than this. In How scheduling jobs are queued, we’ll cover how they can be used to request a future state, which is useful to steer the scheduling.