Diesel Genset

The Schematic Editor library block from the Microgrid section shown in Table 1, models a diesel generator implemented as a synchronous machine with speed and voltage control done through a governor and an exciter respectively. Active and reactive power are controlled through secondary control loops that add offset bias to speed and voltage references. The Diesel Genset can disconnect from the grid through its controlled circuit breaker and reconnect by synching to the grid. The following sections describe in more details the component parameters, inputs and outputs.

Table 1. Diesel Genset component in the Schematic Editor core library
component	component dialog window	component parameters
Diesel Genset		Property tabs: 1 - Basic 2 - Synchronous machine electrical 3 - Synchronous machine mechanical 4 - Governor and engine 5 - Exciter 6 - Advanced 1 7 - Advanced 2 8 - Advanced 3

Figure 1. Diesel Genset component view under its mask

Inputs and outputs

The Diesel Genset component needs 9 inputs to operate. These inputs must be sent as an array, with use of a Bus Join component, and in the correct order. Table 2 describes the inputs and their order.

Table 2. Diesel Genset inputs
Number	Input	Description
0	Gen_on	A digital input that turns the generator on/off. Generator is on with a high input.
1	Vref	An analog input that sets the machine's terminal voltage reference in per unit, where 1.0 is the nominal voltage defined in the component's mask.
2	wref	An analog input that sets the machine's mechanical speed reference in per unit, where 1.0 is the nominal mechanical speed defined in the component's mask through the nominal electrical frequency and number of pole pairs.
3	Pref	An analog input that sets the machine's active power output in per unit, where 1.0 is the nominal power defined in the component's mask.
4	pf_ref	An analog input that defines the machine's reactive power output based on the power factor reference.
5	Gen_OP_mode	A three-level input that defines the generator operation mode: 0 - Stand By. The generator can turn on, but will not connect to the grid. 1 - Grid Following. The generator syncs to the grid and connects. 2 - Grid Forming. The generator forces its contactor closed and operates regulating voltage and frequency.
6	Gen_Control_mode	A three-level input that defines the generator control mode: 0 - Vf. Voltage and frequency control mode. 1 - PV. Active power and voltage control mode. 2 - P-pf. Active and reactive power control mode. Reactive power output is based on the power factor reference.
7	Load_share_on	A digital input that turns the load share function on/off. The load share function is on with a high input.
8	Load_share	An analog input that offsets the speed bias calculated by the frequency setpoint control loop, this changes the machine's active power output.

The Diesel Genset has 14 outputs. They are organized as an array and can be accessed individually through a Bus Split component, respecting the correct order. Table 3 describes the outputs and their order.

Table 3. Diesel Genset outputs
Number	Output	Description
0	Gen_On	A digital output with a feedback of the generator on/off state. Generator is on when output is high.
1	wmeas	An analog output with the measured mechanical speed. [rad/s]
2	GCB_status	A digital output with a feedback of the circuit breaker on/off state. Circuit breaker is closed when the output is high.
3	Va	An analog output with the instantaneous measurement of the machine's phase A terminal voltage. [V]
4	Vb	An analog output with the instantaneous measurement of the machine's phase B terminal voltage. [V]
5	Vc	An analog output with the instantaneous measurement of the machine's phase C terminal voltage. [V]
6	Vt	An analog output with the machine's terminal peak voltage (phase to neutral). [V]; The RMS voltage can be calculated by dividing this output by a square root of 2.
7	Ia	An analog output with the instantaneous measurement of the machine's phase A terminal current. [A]
8	Ib	An analog output with the instantaneous measurement of the machine's phase B terminal current. [A]
9	Ic	An analog output with the instantaneous measurement of the machine's phase C terminal current. [A]
10	P	An analog output with the machine's active power measurement. [W]
11	Q	An analog output with the machine's reactive power measurement. [VAr]
12	S	An analog output with the machine's apparent power measurement. [VA]
13	pf	An analog output with the machine's power factor measurement.

Component dialog box and parameters

The Diesel Genset component dialogue box consists of eight tabs for specifying basic and advanced parameters.

Tab: "1 - Basic"

In this component tab, you can specify basic parameters of the Diesel Genset.

Figure 2. Diesel Genset "1 - Basic" parameters

Table 4. Diesel Genset "1 - Basic" parameters
Parameter	Code name	Description
Nominal power	Sb	Diesel Genset nominal power. [VA]
Phase nominal voltage	Vn	Diesel Genset nominal line to line terminal voltage. [V]
Nominal electrical frequency	f	Diesel Genset nominal electrical frequency. [Hz]
Shunt snubber load percentage of nominal power	load	Percentage of the nominal power to be added to a resistive shunt load connected to the terminals of the machine. [%]; Adjustment of this value can contribute to simulation stability.
Execution rate	Ts	Execution rate of all signal processing components of the diesel genset. [s]

Tab: "2 - Synch, Mach. - Elec."

In this component tab, you can specify electrical parameters of the synchronous machine used in the Diesel Genset.

Figure 3. Diesel Genset "2 - Synch. Mach. - Elec." parameters

Table 5. Diesel Genset "2 - Synch. Mach. - Elec." parameters
Parameter	Code name	Description
Rs	Rs	Stator phase resistance. [Ω]
Lls	Lls	Stator phase leakage inductance. [H]
Lmd	Lmd	Magnetizing inductance in d-axis. [H]
Lmq	Lmq	Magnetizing inductance in q-axis. [H]
Rf	Rf_prime	Field winding resistance. [Ω]; value referred to the stator.
Llfd	Llfd_prime	Field winding leakage inductance in q-axis. [H]; value referred to the stator.
Rkd	Rkd	d-axis damper winding resistance. [Ω]; value referred to the stator.
Rkq	Rkq	q-axis damper winding resistance. [Ω]; value referred to the stator.
Llkd	Llkd	Damper phase winding leakage inductance in d-axis. [H]; value referred to the stator.
Llkq	Llkq	Damper phase winding leakage inductance in q-axis. [H]; value referred to the stator.
Ns/Nfd	Ns_Nfd	Turns ratio between stator phase winding and field winding; used for referring field winding variables to the stator.
Ns/Nkd	Ns_Nkd	Turns ration between stator phase winding and d-axis damper winding; used for referring damper winding variables to the stator.
Ns/Nkq	Ns_Nkq	Turns ratio between stator phase winding and q-axis damper winding; used for referring damper winding variables to the stator.

Tab: "3 - Synch. Mach. - Mec."

In this component tab, you can specify mechanical parameters of the synchronous machine used in the Diesel Genset.

Figure 4. Diesel Genset "3 - Synch. Mach. - Mec." parameters

Table 6. Diesel Genset "3 - Synch. Mach. - Mec." parameters
Parameter	Code name	Description
pms	pms	Synchronous machine number of pole pairs.
Jm	J	Combined rotor and load moment of inertia. [Kg.m²]
Friction coefficient	F	Synchronous machine viscous friction coefficient. [Nms]

Tab: "4 - Gov. and Eng."

In this component tab, you can specify parameters for the governor and engine used in the Diesel Genset. The governor and engine are implemented with Woodward's DEGOV model.

Figure 5. Diesel Genset "4 - Gov. and Eng." parameters

Table 7. Diesel Genset "4 - Gov. and Eng." parameters
Parameter	Code name	Description
Electric control box time constant 1	T1	Governor's electric control box time constant T1. [s]
Electric control box time constant 2	T2	Governor's electric control box time constant T2. [s]
Electric control box time constant 3	T3	Governor's electric control box time constant T3. [s]
Actuator gain K	k	Governor's actuator gain K.
Actuator time constat 4	T4	Governor's actuator time constant T4. [s]
Actuator time constant 5	T5	Governor's actuator time constant T5. [s]
Actuator time constant 6	T6	Governor's actuator time constant T6. [s]
Initial mechanical power	Pm0	Governor's initial mechanical power output. [p.u.]
Maximum torque limit	Tmax	Governor's maximum torque output. [p.u.]
Minimum torque limit	Tmin	Governor's minumum torque output. [p.u.]
Engine time delay	Td	Engine's time delay. [s]

Tab: "5 - Exciter"

In this component tab, you can specify parameters for the exciter used in the Diesel Genset. The exciter is implemented with IEEE's DC4B model.

Figure 6. Diesel genset "5 - Exciter" parameters.

Table 8. Diesel Genset "5 - Exciter" parameters
Parameter	Code name	Description
Time constant Tr	Tr	Transducer time constant Tr. [s]
Exciter PI proportional gain	exc_Kp	Exciter's regulator PI controller proportional gain Kp.
Exciter PI integral gain	exc_Ki	Exciter's regulator PI controller integral gain Ki.
Major regulator gain Ka	Ka	Exciter's regulator output gain Ka.
Major regulator time constant Ta	Ta	Exciter's regulator output time constant Ta. [s]
Saturation upper limit	Vrmax	Exciter's regulator maximum voltage output. [p.u.]
Saturation lower limit	Vrmin	Exciter's regulator minimum voltage output. [p.u.]
Exciter time constant Te	Te	Exciter field time constant Te. [s]
Exciter gain Ke	Ke	Exciter field proportional constant Ke.
Stabilization feedback gain Kf	Kf	Exciter rate feedback gain Kf.
Stabilization feedback time constant Tf.	Tf	Exciter rate feedback time constant Tf. [s]
Initial terminal voltage	Vt0	Exciter initial terminal voltage input. [p.u.]
Initial field voltage	Vf0	Exciter initial field voltage output. [p.u.]
Exciter saturation upper limit	Efmax	Exciter maximum output voltage. [p.u.]
Exciter saturation lower limit	Efmin	Exciter minimum output voltage. [p.u.]

Tab: "6 - Adv. 1"

In this component tab, you can specify advanced parameters for the synch check control used in the Diesel Genset.

Figure 7. Diesel Genset "6 - Adv. 1" parameters.

Table 9. Diesel Genset "6 - Adv. 1" parameters
Parameter	Code name	Description
Synch Check - accepted frequency difference	delta_f	Accepted electrical frequency difference between generator and grid to close the main contactor. [%]
Synch Check - accepted phase difference	delta_phi	Accepted phase difference between generator and grid to close the main contactor. [degrees]
Synch Check - Phase PI - Kp	phase_Kp	Phase match PI controller proportional gain Kp.
Synch Check - Phase PI - Ki	phase_Ki	Phase match PI controller integral gain Ki.
Synch Check - Phase PI - Upper limit	phase_upLim	Phase match PI controller maximum output.
Synch Check - Phase PI -Lower limit	phase_lowLim	Phase match PI controller minimum output.
Synch Check - Phase calibration	phaseOff	Phase offset input to synchronize both grid and generator PLLs. [degrees]; To calibrate correctly, let the Diesel Genset connect to the grid and measure the phase difference at that moment. Set the opposite of that value as the offset.
Synch Check - delta w gain	dw_K	Synching speed bias output proportional gain Kp.
Synch Check - Voltage PI - Kp	V_Kp	Voltage match PI controller proportional gain Kp.
Synch Check - Voltage PI - Ki	V_Ki	Voltage match PI controller integral gain Ki.
Synch Check - Voltage PI - Upper limit	V_upLim	Voltage match PI controller maximum output
Synch Check - Voltage PI - Lower limit	V_lowLim	Voltage match PI controller minimum output.
Synch Check - Accepted voltage difference	delta_V	Accepted voltage difference between generator and grid to close main contactor. [%]

Tab: "7 - Adv. 2"

In this component tab, you can specify advanced parameters for the frequency setpoint control and governor inputs used in the Diesel Genset. The frequency setpoint control can operate in both frequency droop or active power control mode.

Figure 8. Diesel Genset "7 - Adv. 2" parameters

Table 10. Diesel Genset "7 - Adv. 2" parameters
Parameter	Code name	Description
Frequency setpoint loop - PI -Kp	w_sp_Kp	Frequency setpoint PI controller proportional gain Kp.
Frequency setpoint loop - PI - Ki	w_sp_Ki	Frequency setpoint PI controller integral gain Ki.
Frequency setpoint loop - PI - Upper limit	w_sp_upLim	Frequency setpoint PI controller maximum output. [p.u.]
Frequency setpoint loop - PI - Lower limit	w_sp_lowLim	Frequency setpoint PI controller minimum output. [p.u.]
Frequency setpoint loop - P droop	P_droop	Frequency setpoint active power droop.
Frequency setpoint loop - P rising rate	P_rise	Frequency setpoint active power reference rising rate. [p.u./s]
Frequency setpoint loop - P falling rate	P_fall	Frequency setpoint active power reference falling rate. [p.u./s]
Frequency setpoint loop - w droop	w_droop	Frequency setpoint speed droop.
Frequency setpoint loop - w rising rate	w_rise	Frequency setpoint speed reference rising rate. [p.u./s]
Frequency setpoint loop - w falling rate	w_fall	Frequency setpoint speed reference falling rate. [p.u./s]
Governor - Accepted nominal speed difference	delta_wn	Accepted speed difference between the actual speed and the nominal speed to start synch check control. [%]
Governor - inner w droop	inner_w_droop	Governor inner speed droop.
Governor - inner w rise	inner_w_rise	Governor inner speed reference rising rate. [p.u./s]
Governor - inner w fall	inner_w_fall	Governor inner speed reference falling rate. [p.u./s]

Tab: "8 - Adv. 3"

In this component tab, you can specify advanced parameters for the power factor control and exciter inputs used in the Diesel Genset.

Figure 9. Diesel Genset "8 - Adv. 3" parameters.

Table 11. Diesel Genset "8 - Adv. 3" parameters
Parameter	Code name	Description
Power factor loop - PI - Kp	pf_Kp	Power factor PI controller proportional gain Kp.
Power factor loop - PI - Ki	pf_Ki	Power factor PI controller integral gain Ki.
Power factor loop - PI - Upper limit	pf_upLim	Power factor PI controller maximum output.
Power factor loop - PI - Lower limit	pf_lowLim	Power factor PI controller minimum output.
Exciter - start speed	exc_dwn	Minimum mechanical speed to start exciter. [%]
Exciter - V rising rate	V_rise	Exciter voltage reference rising rate. [p.u./s]
Exciter - V falling rate	V_fall	Exciter voltage reference falling rate. [p.u./s]
Exciter - V inner droop	V_inner_droop	Exciter inner voltage droop.

Example

Overall behavior and control methodologies can be better understood with the use of the given Diesel Genset example:

Model name: diesel_genset.tse

SCADA interface: SCADA_Panel.cus

Path: /examples/models/microgrid/diesel_genset/