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inverter – converts direct current (DC) (e.g. from solar panels or batteries) to alternating current (AC).

Synopsis

module generators;
class inverter {
        enumeration {FOUR_QUADRANT=4, PWM=3, TWELVE_PULSE=2, SIX_PULSE=1, TWO_PULSE=0} inverter_type;
        enumeration {NONE=0,CONSTANT_PQ=1,CONSTANT_PF=2, VOLT_VAR=4  New in 3.2! , LOAD_FOLLOWING=5, GROUP_LOAD_FOLLOWING=6} four_quadrant_control_mode;
        enumeration {INCLUDED,EXCLUDED} pf_reg
        enumeration {ONLINE=2, OFFLINE=1} generator_status;
        enumeration {SUPPLY_DRIVEN=5, CONSTANT_PF=4, CONSTANT_PQ=2, CONSTANT_V=1, UNKNOWN=0} generator_mode;
        complex V_In[V];
        complex I_In[A];
        complex VA_In[VA];
        complex VA_Out[VA]
        complex Vdc[V];
        complex phaseA_V_Out[V];
        complex phaseB_V_Out[V];
        complex phaseC_V_Out[V];
        complex phaseA_I_Out[A];
        complex phaseB_I_Out[A];
        complex phaseC_I_Out[A];
        complex power_A[VA];
        complex power_B[VA];
        complex power_C[VA];
        complex P_Out[VA];
        complex Q_Out[VAr];
        complex power_factor[unit];
        double power_in[W]; 
        double rated_power[VA]; 
        double rated_battery_power[W]; 
        double inverter_efficiency; 
        double battery_soc[pu]; 
        double soc_reserve[pu]; 
        bool use_multipoint_efficiency; 
        enumeration {XANTREX=3, SMA=2, FRONIUS=1, NONE=0} inverter_manufacturer;
        double maximum_dc_power[W];
        double maximum_dc_voltage[V];
        double minimum_dc_power[W];
        double c_o[1/W];
        double c_1[1/V];
        double c_2[1/V];
        double c_3[1/V];
        set {S=112, N=8, C=4, B=2, A=1} phases;
        object sense_object;
        double max_charge_rate[W];
        double max_discharge_rate[W];
        double charge_on_threshold[W];
        double charge_off_threshold[W];
        double discharge_on_threshold[W];
        double discharge_off_threshold[W];
        double excess_input_power[W];
        double charge_lockout_time[s];
        double discharge_lockout_time[s];
        double pf_reg_activate;
        double pf_reg_deactivate;
        double pf_reg_activate_lockout_time[s];
        double charge_threshold[W];
        double discharge_threshold[W];
        double group_max_charge_rate[W];
        double group_max_discharge_rate[W];
        double group_rated_power[W];
        double V_base[V];  New in 3.2! 
        double V1[pu];  New in 3.2! 
        double V2[pu];  New in 3.2! 
        double V3[pu];  New in 3.2! 
        double V4[pu];  New in 3.2! 
        double Q1[pu];  New in 3.2! 
        double Q2[pu];  New in 3.2! 
        double Q3[pu];  New in 3.2! 
        double Q4[pu];  New in 3.2! 
}

Properties

User-Defined

Property name Type Unit Description
inverter_type enumeration none Defines type of inverter technology and efficiency of the unit (FOUR_QUADRANT , PWM, TWELVE_PULSE, SIX_PULSE, TWO_PULSE)
generator_status enumeration none Defines if generator is in operation or not (ONLINE, OFFLINE)
generator_mode enumeration none Control mode of the inverter (SUPPLY_DRIVEN, CONSTANT_PF, CONSTANT_PQ, CONSTANT_V, UNKNOWN)
four_quadrant_control_mode enumeration none Control mode of the inverter when FOUR_QUADRANT (NONE, CONSTANT_PQ, CONSTANT_PF, CONSTANT_V, VOLT_VAR)
V_In complex V DC voltage passed in by the DC object (e.g. solar panel or battery)
I_In complex A DC current passed in by the DC object (e.g. solar panel or battery)
Vdc complex V Not used at this time
power_factor double unit Defines desired power factor in generator mode CONSTANT_PF mode and in four quadrant control mode CONSTANT_PF
P_Out double VA Value to output in four quadrant control mode CONSTANT_PQ
Q_Out double VAr Value to output in four quadrant control mode CONSTANT_PQ
use_multipoint_efficiency bool none A boolean flag to toggle using Sandia National Laboratory's multipoint efficiency model
inverter_manufacturer enumeration none Defines default parameters for the multipoint efficiency model for an inverter from manufacturer (NONE, FRONIUS, SMA, XANTREX)
maximum_dc_power double W The maximum DC power rating of the inverter, only used when use_multipoint_efficiency is TRUE
maximum_dc_voltage double V The maximum DC voltage rating of the inverter, only used when use_multipoint_efficiency is TRUE
minimum_dc_power double W The minimum DC voltage rating of the inverter, only used when use_multipoint_efficiency is TRUE
c_o double 1/W The coefficient descibing the parabolic relationship between AC and DC power of the inverter, only used when use_multipoint_efficiency is TRUE
c_1 double 1/V The coefficient allowing the maximum DC power to vary linearly with DC voltage, only used when use_multipoint_efficiency is TRUE
c_2 double 1/V The coefficient allowing the minimum DC power to vary linearly with DC voltage, only used when use_multipoint_efficiency is TRUE
c_3 double 1/V The coefficient allowing c_0 to vary linearly with DC voltage, only used when use_multipoint_efficiency is TRUE
sense_object object none FOUR QUADRANT MODEL: name of the object the inverter is trying to mitigate the load on (node/link) in LOAD_FOLLOWING and supplement mode pf_reg
max_charge_rate double W FOUR QUADRANT MODEL: name of the object the inverter is trying to mitigate the load on (node/link) in LOAD_FOLLOWING
max_discharge_rate double W FOUR QUADRANT MODEL: maximum rate the battery can be discharged in LOAD_FOLLOWING
charge_on_threshold double W FOUR QUADRANT MODEL: power level of the sense_object at which the inverter should try charging the battery in LOAD_FOLLOWING
charge_off_threshold double W FOUR QUADRANT MODEL: power level of the sense_object at which the inverter should cease charging the battery in LOAD_FOLLOWING
discharge_on_threshold double W FOUR QUADRANT MODEL: power level of the sense_object at which the inverter should try discharging the battery in LOAD_FOLLOWING
discharge_off_threshold double W FOUR QUADRANT MODEL: power level of the sense_object at which the inverter should cease discharging the battery in LOAD_FOLLOWING
excess_input_power double W FOUR QUADRANT MODEL: Excess power at the input of the inverter that is otherwise just lost, or could be shunted to a battery
charge_lockout_time double s FOUR QUADRANT MODEL: Lockout time when a charging operation occurs before another LOAD_FOLLOWING dispatch operation can occur
discharge_lockout_time double s FOUR QUADRANT MODEL: Lockout time when a discharging operation occurs before another LOAD_FOLLOWING dispatch operation can occur
pf_reg_activate double none FOUR QUADRANT MODEL: Lowest acceptable power-factor level of the sense_object below which power-factor regulation will activate. Default value is 0.8.
pf_reg_deactivate double none FOUR QUADRANT MODEL: Lowest acceptable power-factor of the sense_object above which no power-factor regulation is needed. Default value is 0.95.
pf_reg_activate_lockout_time double s FOUR QUADRANT MODEL: Mandatory pause between the deactivation of power-factor regulation and it reactivation. Default value is 60s.
charge_threshold double W FOUR QUADRANT MODEL: Level at which all inverters in the group will begin charging attached batteries. Regulated minimum load level
discharge_threshold double W FOUR QUADRANT MODEL: Level at which all inverters in the group will begin discharging attached batteries. Regulated maximum load level
group_max_charge_rate double W FOUR QUADRANT MODEL: Sum of the charge rates of the batteries involved in the group load-following
group_max_discharge_rate double W FOUR QUADRANT MODEL: Sum of the discharge rates of the batteries involved in the group load-following
group_rated_power double W FOUR QUADRANT MODEL: Sum of the inverter power ratings of the inverters involved in the group power-factor regulation
V_base double V FOUR QUADRANT MODEL: The base voltage on the grid side of the inverter. Used in VOLT_VAR control mode
V1 double pu FOUR QUADRANT MODEL: voltage point 1 in volt/var curve. Used in VOLT_VAR control mode
V2 double pu FOUR QUADRANT MODEL: voltage point 2 in volt/var curve. Used in VOLT_VAR control mode
V3 double pu FOUR QUADRANT MODEL: voltage point 3 in volt/var curve. Used in VOLT_VAR control mode
V4 double pu FOUR QUADRANT MODEL: voltage point 4 in volt/var curve. Used in VOLT_VAR control mode
Q1 double pu FOUR QUADRANT MODEL: VAR point 1 in volt/var curve. Used in VOLT_VAR control mode
Q2 double pu FOUR QUADRANT MODEL: VAR point 2 in volt/var curve. Used in VOLT_VAR control mode
Q3 double pu FOUR QUADRANT MODEL: VAR point 3 in volt/var curve. Used in VOLT_VAR control mode
Q4 double pu FOUR QUADRANT MODEL: VAR point 4 in volt/var curve. Used in VOLT_VAR control mode

Not User-Defined

Property name Type Unit Description
VA_In complex VA Power passed in by the DC object (e.g. solar panel or battery) – V_In * I_In
phaseA_V_Out complex V AC voltage coming from the interconnection point
phaseB_V_Out complex V AC voltage coming from the interconnection point
phaseC_V_Out complex V AC voltage coming from the interconnection point
phaseA_I_Out complex A AC current being delivered to the interconnection point
phaseB_I_Out complex A AC current being delivered to the interconnection point
phaseC_I_Out complex A AC current being delivered to the interconnection point
power_A complex VA Calculation of power delivered to interconnection node
power_B complex VA Calculation of power delivered to interconnection node
power_C complex VA Calculation of power delivered to interconnection node
phases set none Not used at this time-- phases assumed from interconnection point(A,B,C,N,S)

Default Inverter

The minimum definition for an inverter is

object inverter {
        generator_mode CONSTANT_PF;
        << implied child that provides a DC power input >>
}

Example

module generators;
object inverter {
     generator_mode CONSTANT_PF;
     generator_status ONLINE;
     inverter_type PWM;
     power_factor 1.0;
     parent triplex_meter2;
     << implied child that provides a DC power input >>
}

Volt/Var Control Mode  New in 3.2! 

The VOLT_VAR mode is used to have the inverter generate/absorb VARs based off of the system voltage seen at the inverter terminals. The output on each phase determined on the system voltage measured on said phase. for example, in a three phase inverter, the output on phase A is based off of the phase A voltage measurement, the output on phase B is based off of the phase B voltage measurement, and the output on phase C is based off of the phase C voltage measurement. The inverter determines how much VARs are generated or absorbed by a volt/VAR curve that the user creates by setting the V1, V2, V3, V4, Q1, Q2, Q3, and Q4 parameters. See the illustration below showing curve generated by these parameters.

VoltVARcurve.JPG

The values of these parameters is per unit. V_base is used to convert the voltage measurement to a per unit value. The rated_power parameter is used to convert the per unit value of VAR output into VARs. Note that rated_power is a per-phase limit, so for three-phase inverters, the overall limit will be three-times that value. The inverter will try to output the amount of VARs determined from the curve without exceeding the power curve of the inverter.

object inverter {
    name volt_var_inv;
    parent inv_meter;
    inverter_type FOUR_QUADRANT;
    four_quadrant_control_mode VOLT_VAR;
    generator_status ONLINE;
    generator_mode SUPPLY_DRIVEN;
    phases ABC;
    rated_power 70 kVA;// per phase;
    inverter_efficiency 0.87;
    //Volt Var parameters;
    V_base 7200;
    V1 0.90;
    Q1 0.7;
    V2 0.95;
    Q2 0.0;
    V3 1.05;
    Q3 0.0;
    V4 1.10;
    Q4 -0.8;
}

Bugs

See Also