Basler DECS-250 Excitation System Debugging Guide

Transformers tab

Generator VT Configuration (single-phase/open delta/three wire star/four wire star), VT Primary/Secondary voltage.

Bus VT Configuration (similar, with Dual Breaker option).

Generator CT Primary/Secondary current (1A or 5A).

Cross current CT primary/secondary current.

Excitation tab

Soft Start Initial Voltage (%), Soft Start Time (seconds).

Overexcitation Voltage Setpoint and Time Delay.

Loss of Excitation Current Setpoint and Delay.

Rotating Diode Fault parameters (number of main poles, number of excitation poles, detection level and delay of on/off diodes).

Excitation Select (PMG or Shun), PMG Phase Select (single-phase or three-phase).

Volts/Hz tab

Upper/Lower Knee Frequency and Upper/Lower Slope can be viewed by clicking on "Validate&Graph".

OEL tab

Check 'Overexcitation Limiting Enable' and set the high, medium, and low current settings and time limits for online/offline OEL. Please note that there are three levels of online OEL and two levels of offline OEL.

UEL tab

Check 'Underexcitation Limiting Enable' and enter 5 (power, reactive power) points to construct a polyline limit curve.

Gain tab

PID parameters (Kp, Ki, Kd, Td) and Overall Gain Kg for AVR/FCR.

Proportional gain (Ki) and total gain (Kg) controlled by PF and Var.

Integral gain (Ki) and total gain (Kg) of OEL and UEL.

Cross Current Gain, AVR/FCR Auxiliary Gain PF/Var Auxiliary Gain。

These gain parameters are stored in the Unscheduled Write data table and need to be written to DECS-250 using the MSG instruction.

Tracking tab

Internal Tracking Enable, Tracking Rate, Tracking Delay - used for undisturbed tracking during mode switching.

Redundant Tracking Rate, Redundant Tracking Delay - Redundant Hot Spare Tracking.

Traverse Rates (AVR, PF, Var, FCR) - Set the transition time from the tracking value to the target value after switching modes.

Synch tab

The high and low limits and acceptance delay of Frequency/Voltage/Phase Match.

Voltage Multiplier and Phase Offset for Bus A/B are used to compensate for PT ratio and wiring phase differences (e.g. 30 ° offset required for Δ - Y conversion).

Dead Bus Limits (frequency, voltage upper and lower limits).

Generator/Bus Rotation (ABC or ACB).

Load Share tab

Full Scale Voltage (LS output voltage at full load, usually 5V), Limit (maximum load sharing error), Rate (error change rate).

Voltage tab

Overvoltage Setpoint/Delay、Undervoltage Setpoint/Delay。

Droop Percentage (reactive power droop coefficient, 0-30%).

Line Drop Compensation (0-10%).

Current tab

Overcurrent Setpoint (overcurrent setting,% rated current), Overcurrent Curve (16 inverse time curves+time limit), Time Dial, Voltage Braking Setpoint (voltage braking coefficient).

Frequency tab

Overfrequency/Underfrequency Setpoint and Delay.

Power tab

Reverse kW Setpoint and Delay, Reverse kvar Setpoint and Delay.

Fault Relay tab

Check the type of fault that needs to trigger the output of the fault relay (overvoltage, undervoltage, overclocking, reverse power, etc.).

3.3 Configure data writing mechanism

The Configuration data table (including most of the above parameters) is automatically written to DECS-250 in the following two situations: ① when the connection is first established; ② After clicking Apply/OK (excitation must be disabled).

The Gain tab and Line Drop Compensation belong to the Unscheduled Write data table and must be sent by the user program through the MSG command. The example cascade is shown in Figure 6-1 (MSG can be triggered using XIC UnschdWriteRcvd, with the target element being "Module Name: C. UnschWrite").

When the Configuration reception is completed, the position of Config Rcvd is 1; When the Unscheduled Write reception is completed, UnschdWriteRcvd position 1. After both bits are set to 1, DECS-250 accepts the Scheduled Write data and allows excitation.

Detailed explanation of operation mode

The adjustment mode of DECS-250 is selected by the label in the output table, and all modes must meet the following requirements: hardware excitation enable (EX-D+terminal has 24V), software excitation enable (SoftwareExcEn=1), and ControlNet connection is normal.

4.1 Field Current Regulation (FCR)

FCR is in manual mode and directly controls the excitation current. Applicable scenarios: Temporary voltage maintenance during machine testing and AVR faults. Activation condition: AVR-FCR_Select=1 (FCR select), FCRSetpt writes the target current (Adc). In FCR mode, AVR, PF, Var, and all limiters (OEL/UEL) do not work.

4.2 Automatic Voltage Regulation (AVR)

AVR is the default mode, maintaining a constant voltage at the generator terminal. Activation conditions: AVR-FCR_Select=0, V_Droop En=0 (droop disabled), set AVRSetpt (voltage value). The soft start function takes effect in AVR mode: after excitation, the voltage rises from SoftStart_SnitLevel to the set value in a ramp manner according to SoftStartTime.

4.3 Power factor regulation (PF)

PF mode adjusts the excitation to track the power factor to the set value. Activation conditions: AVR-FCR_Select=0, V_DrooopEn=1, Drooop_CCC_Select=0 (select droop), PF_VAR_ En=1, PF_VAR_Select=0 (select PF), set PFSetpt (-0.5~+0.5). PF_Ki and PF_Kg gains need to be configured.