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Overview

This document describes GridLAB-D implementation of diesel generator in PQ constant mode.

A constant_P mode is implemented in the governor type P_CONSTANT:

caption

In the constant_P mode, a time delay is applied to the electric power output from the diesel generator. The delayed electric power output is compared with the constant real power reference, then applied to a PI controller, to get the actuator input. The actuator part and time delay part of the GGOV01 governor is used in constant_P mode. Output of the constant_P mode is the mechanical power of the diesel generator.

The constant_Q mode is implemented based on the existing exciter SEX_PTI:

caption

GridLAB-D Implementation

Diesel Generator in PQ Constant mode example

This diesel generator object is implemented in both constant P and constant Q mode.

By selecting Governor_type as P_CONSTANT, the constant P mode is selected. This example sets ''Pref'' value as 0.5 p.u. The PI controller settings for the constant Pref mode are 0 for proportional control, and 0.05 for integral control. In addition, parameters of the actuator and time delay part of the P_CONSTANT are also defined in the example.

By selecting Exciter_Q_constant_mode as true, the constant Q mode is selected. This example sets ''Qref'' value as 0.6 p.u.. The PI controller settings for the constant Q mode are 0.01 for proportional control, and 0.05 for integral control.

Example of Diesel Generator in PQ Constant mode

module generators;
object diesel_dg {
     flags DELTAMODE;
     parent 8;
     name Gen2;
     Rated_V 4156; //Line-to-Line value
     Rated_VA 1000000; // Defaults to 10 MVA
     Gen_type DYN_SYNCHRONOUS;
     rotor_speed_convergence ${rotor_convergence};
     Exciter_type SEXS;
     Governor_type P_CONSTANT;
     // Actuator and time delay parameters for P_CONSTANT mode
     P_CONSTANT_Tpelec 1.0; // Electrical power transducer time constant, sec. (>0.)
     P_CONSTANT_Tact 0.05; //0.5; // Actuator time constant
     P_CONSTANT_Kturb 1.5; // Turbine gain (>0.)
     P_CONSTANT_wfnl 0.2; //0.2; // No load fuel flow, p.u
     P_CONSTANT_Tb 0.01;//0.1; // Turbine lag time constant, sec. (>0.)
     P_CONSTANT_Tc 0.2; // Turbine lead time constant, sec.
     P_CONSTANT_Teng 0.0; // Transport lag time constant for diesel engine
     P_CONSTANT_ropen 050; // Maximum valve opening rate, p.u./sec.
     P_CONSTANT_rclose -050; // Minimum valve closing rate, p.u./sec.
     P_CONSTANT_Kimw 0.0;//0.002; // Power controller (reset) gain 
     inertia 2.5;
     // PI controller parameters of P_CONSTANT mode
     P_CONSTANT_Pref 0.5; // Set P reference, p.u. 
     P_CONSTANT_kp 0;  // ki for the PI controller implemented in P constant delta mode
     P_CONSTANT_ki 0.05;  // kp for the PI controller implemented in P constant delta mode
     Exciter_Q_constant_Qref 0.6; // Set Q reference, p.u. 
     Exciter_Q_constant_mode true; // Flag indicating whether the diesel generator exciter is operating based on Qref given
     Exciter_Q_constant_kp 0.01;  // ki for the PI controller implemented in Q constant delta mode

}

Properties

This table lists the properties related to diesel generator in PQ constant mode. Some parameters used by diesel_dg can be found in the diesel_dg wiki page.

Property name Type Unit Description
Gen_type enumeration none Defines type of diesel generator (INDUCTION , SYNCHRONOUS, DYN_SYNCHRONOUS).
Should choose DYN_SYNCHRONOUS for diesel generator in PQ constant mode.
rotor_speed_convergence double rad Convergence criterion on rotor speed used to determine when to exit deltamode
Exciter_type enumeration none Exciter model for dynamics-capable implementation (NO_EXC , SEXS).
Should choose [[diesel_dg_type|SEXS] for this diesel generator in PQ constant mode.
Governor_type enumeration none Governor model for dynamics-capable implementation (NO_GOV , DEGOV1, GAST, GGOV1_OLD, GGOV1, P_CONSTANT).
Should choose P_CONSTANTfor this diesel generator in PQ constant mode.
Parameters related to P constant mode
P_CONSTANT_Pref double none Pref value for P constant mode
P_CONSTANT_kp double none Parameter of the proportional control for constant P mode
P_CONSTANT_ki double none Parameter of the integration control for constant P mode
P_CONSTANT_Tpelec double s Electrical power transducer time constant
P_CONSTANT_Tact double s Actuator time constant
P_CONSTANT_Kturb double none Turbine gain
P_CONSTANT_wfnl double none No load fuel flow
P_CONSTANT_Tb double s Turbine lag time constant
P_CONSTANT_Tc double s Turbine lead time constant
P_CONSTANT_Teng double s Transport lag time constant for diesel engine
P_CONSTANT_ropen double /s Maximum valve opening rate
P_CONSTANT_rclose double /s Minimum valve closing rate
P_CONSTANT_Kimw double /s Power controller (reset) gain
Parameters related to Q constant mode
Exciter_Q_constant_Qref double none Qref value for Q constant mode
Exciter_Q_constant_mode double none True if the generator is operating under constant Q mode
Exciter_Q_constant_kp double none Parameter of the proportional control for constant Q mode
Exciter_Q_constant_ki double none Parameter of the integration control for constant Q mode

Test cases

In order to verify the implementation of PQ_CONSTANT mode diesel generator, a test case in 123-bus feeder with one isochronous mode diesel_dg Gen 1, and one PQ_CONSTANT mode diesel_dg Gen 2is applied. At 5.001 second, part of the feeder is disconnected. Gen 1 will reduce its generation, and Gen 2 will maintain its generation after the transient. Below diagram shows the generation from the two generators before and after the transient.

caption

To run this case, please find in the autotest in GridLAB-D generator module.

See Also