Meter Modules not Calculating Monthly Cost Correctly

[Ali Khan]

Hello Gridlab-D Team,

Hope your day is going great today.

I am updating prices inside meter modules of gridlab-d through Helics. This price is updated on every iteration. The meter module is supposed to calculate the monthly_bill taking into account the correct price variation and then calculating in somewhat I would call a 'running sum'.

The meter module however, calculates a spot sum. It multiplies all the value of energy flowing by the current price.

See attached image for how it looks like.

Here is my meter module code:

object meter                                                    // BESS L1 - 1 kWh
{
    name                                                        Mtr_Batt_JohnsonHall;
    bill_mode                                                   UNIFORM;
    nominal_voltage                                             277;
    phases                                                      ABCN;
    price                                                       0;
    parent                                                      JohnsonHall_SEC;
    object recorder  
    { 
        property                              measured_real_power, measured_real_energy, price, monthly_bill;
        interval                              300; 
        file                                  Batt-JohnsonHall.csv; 
    };
}

I am referencing this definition of the UNIFORM billing mode:

1 - UNIFORM - A static price is used through variable price, however, this may change over time using a player or schedule.

[Ali Khan]

Good Morning Gridlab-D Team,

Any hope with this?

Thanks,
Ali

[Andy Fisher]

Hello Ali,

I can see your confusion on UNIFORM bill mode. The description on that mode is misleading. While the price can fluctuate via a schedule or player it supposed to represent the the mean price in a uniform distribution over the month and not a spot calculation. To get the desired behavior you want you can use the TIERED_TOU mode. Your HELICS configuration should send your prices to the first_tier_price property. An example meter should look like

object meter                                                    // BESS L1 - 1 kWh
{
    name                                                        Mtr_Batt_JohnsonHall;
    bill_mode                                                   TIERED_TOU;
    nominal_voltage                                             277;
    phases                                                      ABCN;
    first_tier_price                                            0.0;
    first_tier_energy                                           0.0;
    parent                                                      JohnsonHall_SEC;
    object recorder  
    { 
        property                              measured_real_power, measured_real_energy, price, monthly_bill;
        interval                              300; 
        file                                  Batt-JohnsonHall.csv; 
    };
}

[Andy Fisher]

Please also note that for a given timestep the bill is calculated using the previous timestep's price properties.