1 About

1.1 Report circulation:

  • Public – this report is intended to accompany the data release.

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1.3 Citation

If you wish to use any of the material from this report please cite as:

  • Anderson, B., Eyers, D., Ford, R., Giraldo Ocampo, D., Peniamina, R., Stephenson, J., Suomalainen, K., Wilcocks, L. and Jack, M. (2019) NZ GREEN Grid Household Electricity Demand Study: 1 minute circuit level electricity power outlier report (version 1.0) , Centre for Sustainability, University of Otago: Dunedin.

This work is (c) 2019 the authors.

1.4 History

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1.5 Support

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2 Introduction

The NZ GREEN Grid household electricity demand study recruited a sample of c 25 households in each of two regions of New Zealand (Stephenson et al. 2017). The first sample was recruited in early 2014 and the second in early 2015. Research data includes:

  • 1 minute electricity power (W) data was collected for each dwelling circuit using GridSpy monitors on each power circuit (and the incoming power). The power values represent mean(W) over the minute preceeding the observation timestamp;
  • Dwelling & appliance surveys;
  • Occupant time-use diaries (focused on energy use).

NB: Version 1 of the data package does not include the time-use diaries.

This report provides an analysis of circuit level negative and outlier power values to be found in the GREEN Grid project (Stephenson et al. 2017) research data.

There are a number of observations that have recorded either very large or negative power. There are at least two potential reasons for this:

  • a Grid Spy sensor was placed on the wrong wire and/or set to the wrong phase
  • a circuit contained a PV inverter which pushes power into the home and which is measured as -ve power (when active)

The following analysis of the incidence of outliers and negative values makes recommendations on actions to take.

The project research sample comprises 44 households. Table 2.1 shows the number for whom valid appliance and survey data is available in this data package. Note that even those which appear to lack appliance data may have sufficient survey data to deduce appliance ownership (see question numbers Q19_* and Q40_*).

Table 2.1: Sample information
Location hasShortSurvey hasLongSurvey hasApplianceSummary nHouseholds
Hawkes Bay NA NA NA 1
Hawkes Bay NA NA Yes 1
Hawkes Bay NA Yes Yes 5
Hawkes Bay Yes NA Yes 13
Taranaki NA Yes NA 12
Taranaki NA Yes Yes 12

3 Key attributes

Table 3.1 shows key attributes for the recruited sample. Note that two GridSpy monitors were re-used and so require new hhIDs to be set from the date of re-use using the linkID variable. This is explained in more detail in the GridSpy processing report. Linkage between the survey and GridSpy data should therefore always use linkID to avoid errors.

Table 3.1: Sample details
hhID linkID Location surveyStartDate nAdults notes r_stopDate hasApplianceSummary PV Inverter Energy Storage
rf_06 rf_06 Taranaki 2014-05-19 09:49:00 2 NA NA NA NA NA
rf_07 rf_07 Taranaki 2014-06-23 21:25:00 2 NA NA NA NA NA
rf_08 rf_08 Taranaki 2014-05-14 12:21:00 2 NA NA NA NA NA
rf_09 rf_09 Taranaki 2014-06-19 11:33:00 2 NA NA NA NA NA
rf_10 rf_10 Taranaki 2014-05-20 17:01:00 2 NA NA Yes NA NA
rf_11 rf_11 Taranaki 2014-06-06 12:16:00 2 NA NA Yes NA NA
rf_12 rf_12 Taranaki 2014-06-16 07:34:00 1 NA NA NA NA NA
rf_13 rf_13 Taranaki 2014-05-14 12:07:00 2 NA NA Yes NA NA
rf_14 rf_14 Taranaki 2014-06-10 11:51:00 1 NA NA Yes NA NA
rf_15 rf_15a Taranaki 2014-06-17 15:38:00 1 Disconnected 15/01/2015 2015-01-15 NA NA NA
rf_15 rf_15b Taranaki 2014-05-16 17:36:00 2 Re-used 15. Then disconnected 02/04/2016 2016-04-02 NA NA NA
rf_16 rf_16 Taranaki 2014-06-10 15:29:00 2 NA NA NA NA NA
rf_17 rf_17a Taranaki 2014-05-14 20:04:00 2 Unusual & specialist energy tech configuration. Disconnected 28/03/2016. 2016-03-28 NA NA NA
rf_17 rf_17b Taranaki 2014-05-22 09:16:00 NA Re-used 17 NA NA NA NA
rf_18 rf_18 Taranaki 2014-05-14 11:20:00 2 NA NA NA NA NA
rf_19 rf_19 Taranaki 2014-05-22 13:37:00 1 NA NA Yes yes NA
rf_20 rf_20 Taranaki 2014-05-14 11:46:00 2 NA NA NA NA NA
rf_21 rf_21 Taranaki 2014-05-20 16:30:00 2 NA NA Yes NA NA
rf_22 rf_22 Taranaki 2014-05-14 11:39:00 2 NA NA Yes NA NA
rf_23 rf_23 Taranaki 2014-05-15 15:51:00 1 NA NA Yes yes yes
rf_24 rf_24 Taranaki 2014-05-14 11:36:00 2 NA NA Yes yes NA
rf_25 rf_25 Taranaki 2014-06-18 13:57:00 1 NA NA Yes NA NA
rf_26 rf_26 Taranaki 2014-06-11 13:34:00 2 NA NA Yes NA NA
rf_27 rf_27 Taranaki 2014-07-03 15:37:00 2 NA NA Yes NA NA
rf_28 rf_28 Hawkes Bay 2015-01-20 12:15:00 2 NA NA Yes yes NA
rf_29 rf_29 Hawkes Bay 2015-02-10 11:39:00 2 NA NA Yes NA NA
rf_30 rf_30 Hawkes Bay 2015-02-03 10:58:00 2 NA NA Yes NA NA
rf_31 rf_31 Hawkes Bay 2015-02-09 08:05:00 3 NA NA Yes NA NA
rf_32 rf_32 Hawkes Bay 2015-02-09 08:35:00 2 NA NA Yes NA NA
rf_33 rf_33 Hawkes Bay 2015-02-09 16:05:00 2 NA NA Yes NA NA
rf_34 rf_34 Hawkes Bay 2015-01-06 10:50:00 3 NA NA Yes NA NA
rf_35 rf_35 Hawkes Bay 2015-02-05 16:00:00 2 NA NA Yes NA NA
rf_36 rf_36 Hawkes Bay 2015-02-10 20:25:00 1 NA NA Yes NA NA
rf_37 rf_37 Hawkes Bay 2015-02-09 18:49:00 2 NA NA Yes NA NA
rf_38 rf_38 Hawkes Bay 2015-02-05 15:30:00 2 NA NA Yes NA NA
rf_39 rf_39 Hawkes Bay 2015-02-05 15:43:00 3 NA NA Yes NA NA
rf_40 rf_40 Hawkes Bay NA 2 NA NA Yes NA NA
rf_41 rf_41 Hawkes Bay 2015-01-12 13:16:00 2 NA NA Yes NA NA
rf_42 rf_42 Hawkes Bay 2015-02-10 18:04:00 2 NA NA Yes NA NA
rf_43 rf_43 Hawkes Bay NA 2 NA NA NA NA NA
rf_44 rf_44 Hawkes Bay 2015-02-04 20:47:00 2 NA NA Yes NA NA
rf_45 rf_45 Hawkes Bay 2015-02-09 13:26:00 2 NA NA Yes NA NA
rf_46 rf_46 Hawkes Bay 2014-12-19 08:40:00 2 very large number of circuits including voltage and reactive (imaginary) power and possible typos or relabelling? NA Yes NA NA
rf_47 rf_47 Hawkes Bay 2015-01-06 09:01:00 3 NA NA Yes NA NA

As we can see there were 4 households with PV inverters. These were:

Table 3.2: Sample details (PV households)
hhID linkID Location surveyStartDate nAdults notes r_stopDate hasApplianceSummary PV Inverter Energy Storage
rf_19 rf_19 Taranaki 2014-05-22 13:37:00 1 NA NA Yes yes NA
rf_23 rf_23 Taranaki 2014-05-15 15:51:00 1 NA NA Yes yes yes
rf_24 rf_24 Taranaki 2014-05-14 11:36:00 2 NA NA Yes yes NA
rf_28 rf_28 Hawkes Bay 2015-01-20 12:15:00 2 NA NA Yes yes NA

4 Check outliers

We would rather not load the entire data for all households to do this so instead we start by investigating negative power in extracts for three different circuit labels:

  • Heat Pump
  • Hot Water
  • Lighting

These were extracted from the processed data using the example extraction code provided in this package.

4.1 Negative power: Heat Pump

As Figure 4.1 shows negative power observations for Heat Pumps are spread across a number of households. It also shows that there is at least one very large outlier reading for rf_27.

## Warning: The following named parsers don't match the column names:
## dateTime_orig, TZ_orig
##      hhID              linkID            r_dateTime                 
##  Length:14250284    Length:14250284    Min.   :2015-04-01 00:00:00  
##  Class :character   Class :character   1st Qu.:2015-06-22 12:39:00  
##  Mode  :character   Mode  :character   Median :2015-09-16 13:12:00  
##                                        Mean   :2015-09-21 08:00:39  
##                                        3rd Qu.:2015-12-17 17:52:00  
##                                        Max.   :2016-03-31 23:59:00  
##    circuit              powerW        
##  Length:14250284    Min.   : -655.00  
##  Class :character   1st Qu.:    0.00  
##  Mode  :character   Median :    0.00  
##                     Mean   :  147.92  
##                     3rd Qu.:   61.29  
##                     Max.   :27759.00
Boxplot of Heat Pump power values per household

Figure 4.1: Boxplot of Heat Pump power values per household

As we can see from Table 4.1 there is only 1 value where power > 10kW. We recommend that this value be excluded from analysis.

Table 4.1: All Heat Pump records where power > 10kW
hhID linkID r_dateTime circuit powerW
rf_27 rf_27 2015-08-22 10:33:00 Heat Pump$2826 27759