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PVDER_flags_variables_methods.md

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PV-DER Simulation Utility initialization, variables, flags, and methods

This document is a supplement to the Jupyter notebook usage example. It provides information on important arguments during object creation, functionalities of various binary flags/variables (object attributes), and attached methods.

Common initialization arguments

  1. verbosity (string): Logging level for objects (available: 'DEBUG','INFO,'WARNING').
  2. identifier (string): User defined identification string that will be added to the object name.

DER model objects

Object type name: SolarPV_DER_ThreePhase,SolarPV_DER_ThreePhaseBalanced,SolarPV_DER_SinglePhase

Essential initialization arguments

  1. Sinverter_rated (float): Inverter power rating in W (Available: 10.0e3, 50.0e3, 250.0e3, default: 50.0e3).
  2. Vrms_rated (float): Inverter voltage rating (L-G RMS) in V (default: None).
  3. standAlone (Boolean): If this flag is True, the DER model is expected to work as a stand alone model connected to a stif voltage source. If False, the DER model expects to recieve voltage values from an external program (default: True).
  4. STEADY_STATE_INITIALIZATION (Boolean): If this flag is True, the states in the dynamic DER model will be initialized with values corresponding to its steady state operating point. If False the states will be initialized with zeroes (default: False).

Voltage ride through variables and flags

  1. LVRT_ENABLE (Boolean): If this flag is True, the low voltage ride through and protection logic will be enabled. If False the DER instance will neither trip nor enter momentary cessation when abnormal low voltage conditions are encountered (default: True).
  2. HVRT_ENABLE (Boolean): If this flag is True, the high voltage ride through and protection logic will be enabled. If False the DER instance will neither trip nor enter momentary cessation when abnormal high voltage conditions are encountered (default: True).
  3. pvderConfig (dict): Specifies the user defined LVRT and HVRT settings. Can be passed as argument when initializing DER object. An arbitrary number of voltage threshold levels can be specified. Each level also has a mode that defines the DER behavior during the ride through. In both modes, once the t_threshold times are breached, the DER is tripped (i.e. power output reduced to zero permanently). The definition of the modes are as follows:
    • momentary_cessation: Power output reduced to zero during the ride through.
    • mandatory_operation: Try to maintain rated power output during the ride through.
    • Example for LVRT setting: 'LVRT':{'0':{'V_threshold':0.5, 't_threshold':1.0, 'mode': 'mandatory_operation'} }
    • Example for HVRT setting: 'HVRT':{'0':{'V_threshold':1.12, 't_threshold':0.5, 'mode': 'momentary_cessation'} }

Other essential variables and flags

  1. LFRT_ENABLE (Boolean): If this flag is True, the low frequency ride through and protection logic will be enabled. If False the DER instance will never trip when abnormal low frequency conditions are encountered (default: False).
  2. VOLT_VAR_ENABLE (Boolean): If this flag is True, Volt-VAR control is enabled during voltage sags within a specified voltage range. If False the DER will neither supply or absorb reactive power when voltage sags are encountered (default: False).
  3. use_frequency_estimate (Boolean): If this flag is True, grid frequency is estimated using the difference between phase angles at two consecutive time steps (default: False).

Essential methods

  1. show_PV_DER_states(quantity): Show the values for the specified DER variable (default: 'voltage').
  2. show_PV_DER_parameters(parameter_type): Show the values for the specified DER parameter (default: 'inverter_ratings').
  3. initialize_parameter_dict(parameter_ID,source_parameter_ID): Initialize a new parameter dictionary.
  4. update_parameter_dict(parameter_ID,parameter_type,parameter_dict): Update an existing parameter dictionary with new values.

Dynamic simulation model objects

Object types: DynamicSimulation

Essential initialization arguments

  1. LOOP_MODE (Boolean): If this flag is True, the simulation is expected to run in a loop and get updated grid voltages at every iteration in the loop (default: False).
  2. COLLECT_SOLUTION (Boolean): If this flag is True, the time series data for states and other variables are collected at the end of every call to the ODE solver (default: True).

Essential variables and flags

  1. tStart (float): Start time for simulation in seconds (default: 0.0 s).
  2. tEnd (float): End time for simulation in seconds (default: 0.5 s).
  3. tInc (float): Time step for simulation in seconds (default: 0.001 s).
  4. jacFlag (Boolean): If this flag is True, the analytical Jacobian will be passed to the SciPy ODE solver which may improve solution time. If this flag is False the solver will have to numerically calculate the Jacobian (default: False).
  5. DEBUG_SIMULATION (Boolean): If this flag is True, the value of the model variables at each time step will be printed to the terminal at each time step. If this flag is False only information from ride through logic will be printed (default: False).
  6. DEBUG_SOLVER (Boolean): If this flag is True, solution status from ODE solver is printed during each call to solver. If False, solution status will only be printed if there is an exception (default: False).
  7. PER_UNIT (Boolean): If this flag is True, all the displayed electrical quantities will be in per unit values. If False, all the displayed quantities will be in actual values (default: True).

Essential methods

1a. run_simulation(): If LOOP_MODE is True the simulation is run from tStart to tEnd with time step of tInc. 1b. run_simulation(gridVoltagePhaseA, gridVoltagePhaseB, gridVoltagePhaseC, y0, t): If LOOP_MODE is True the voltages, states, and time steps need to to be provided at every iteration.

Simulation events object

Object type name: SimulationEvents Note: Grid events are introduced during the simulation only if standAlone flag is True in DER model and LOOP_MODE is False in DynamicSimulation.

Essential initialization arguments

  1. SOLAR_EVENT_ENABLE (Boolean): If this flag is True, any solar events that were added will be introduced during the simulation (default: True).
  2. GRID_EVENT_ENABLE (Boolean): If this flag is True, any grid events that were added will be introduced during the simulation (default: True).

Essential methods

  1. add_grid_event(T, Vgrid, Vgrid_angle, fgrid): Add grid event at T (default: Vgrid=1.0, Vgrid_angle = 0.0, fgrid = 60).
  2. add_solar_event(T, Sinsol): Add solar event at T (default: Sinsol=100).
  3. remove_grid_event(T): Remove all grid events (voltage, phase angle, or frequency) at T.
  4. remove_solar_event(T): Remove solar event at T.
  5. show_events(): Show list of all simulation events in chronological order.

Results object

Object type name: SimulationResults

Essential initialization arguments

  1. PER_UNIT (Boolean): If this flag is True, all the plots for electrical quantities will be in per unit values. If False, all the displayed quantities will be in actual values (default: True).

Essential variables

  1. font_size (int): Font size of text within the plots (default: 18).

Essential methods

  1. plot_DER_simulation(plot_type): Time series plot for specified electrical quantity (Available: 'power','active_power','active_power_Ppv_Pac_PCC','reactive_power','reactive_power_Q_PCC','voltage','voltage_Vdc','voltage_HV','voltage_HV_imbalance','voltage_LV','voltage_Vpcclv','current','duty_cycle','voltage_Vpcclv_all_phases'; default:'power', )