Basler DECS-200-2L excitation system

3.4 Power factor regulation (PF)

Maintain a constant power factor during grid connection, with an accuracy of ± 0.02 PF (within the range of 10% to 100% active power). For example, setting PF=0.80, the actual adjustment range is 0.78-0.82.

3.5 Parallel compensation method

Reactive Droop: Reduce the voltage setting value proportionally based on the reactive current, with an adjustment range of 0-30% (rated voltage).

Reactive Differential: By using an external CT (1A or 5A) to detect the difference in reactive current between each machine, adjust the excitation to evenly distribute the reactive power. If the CT burden is less than 1VA, existing quantitative CT can be utilized.

Line voltage drop compensation: shares parameters with sag, with an adjustment range of -30% to 0.

3.6 Setpoint control mode

DECS-200 supports multiple external setpoint adjustments:

Up/down contact input (dry contact)

Auxiliary analog input (4-20mA or ± 10Vdc)

RS-232 (ASCII command)

RS-485（Modbus）

The traversal speed of each operation mode is independently adjustable, allowing users to customize the speed and feel. In addition, the pre positioning input function can drive the current mode to the preset operating point, and the "hold" or "release" mode can be selected.

Limiter and protection function

DECS-200 integrates multiple limiters to protect the generator and exciter.

4.1 Overexcitation Limit (OEL)

OEL works in all modes (except FCR) to prevent overheating of the magnetic field winding. Provide two types:

Summing Point:

Online: Three current levels: high, medium, and low. High and medium levels can be set with duration limits (0-10 seconds, 0-120 seconds) respectively, while low levels can operate continuously.

Offline: There are two current levels, high and low, and the high level can be set with a time limit (0-10 seconds).

Takeover: Adopting inverse time characteristics, users can set high/low current values and time scales (Time Dial), and different curves can be selected online/offline.

4.2 Underexcitation Limit (UEL)

Prevent the generator from stepping out of step or overheating of the end iron core due to excessive phase advance. Optional:

Internally generated curve (based only on reactive power value at 0kW)

Customizable 5-point polyline (power reactive power) to match the generator capacity curve.

4.3 Stator current limit (SCL)

Monitor the stator current to prevent overheating of the stator winding. The high current level can be set with a time limit (0-60 seconds), while the low current level can operate continuously. SCL only alarms without restrictions in FCR mode.

4.4 volts per hertz limit (V/Hz) or underfrequency limit

Optional:

Underfrequency limiter: slope adjustable from 0 to 3.0 P.U./Hz, transition frequency adjustable from 45 to 65Hz.

V/Hz ratio limiter: Adjust the set point based on the set slope clamp.

4.5 Excitation diode monitoring (EDM)

Detect open/short circuit faults in the rotating diode of the brushless generator. Users are required to input the number of main poles of the generator and the number of poles of the exciter (2-20 each, even numbers), set the ripple threshold and delay (10-60 seconds for open circuit and 5-30 seconds for short circuit). EDM is achieved by analyzing specific harmonic components in the excitation current.

4.6 Generator protection function

Protection function setting range

Generator overvoltage (59) 0-30kV, delay 0.1-60 seconds

Generator undervoltage (27) 0-30kV, delay 0.5-60 seconds

Demagnetization (40) 0-3000Mvar, delay 0.1-9.9 seconds

Loss of test (60FL) 0-100% rated voltage, delay 0-30 seconds

Magnetic field overvoltage (59F) 1-325Vdc, inverse time delay 0.2-30 seconds

Magnetic field overcurrent 0-16Adc, inverse time limit (ANSI C50.13)

Sequential event recording and waveform recording

5.1 Sequential Event Recording (SER)

DECS-200 monitors changes in I/O status, system operation status, and alarm events, and can store 127 time stamped events, which can be read through BESTCOMS software. The time format supports 12/24 hours and daylight saving time, and the date format is d-m-y or m/d/y.

5.2 Oscillography

It can store 8 waveform records, with a maximum of 6 variables per record (such as generator voltage, current, frequency, kW, power factor, excitation voltage, excitation current). Sampling rate: Each record contains 600 data points, and the number of pre trigger points can be adjusted from 0 to 599. The sampling interval is 4ms to 10 seconds (total recording time is 2.4 seconds to 6000 seconds). Trigger method: BESTCOMS manual, logic trigger, level trigger (such as excitation current exceeding limit) or alarm trigger. The recorded data complies with the IEEE COMTRADE standard and can be viewed using Basler BESTwave software.

Communication and software tools

6.1 BESTCOMS ™  Configure software

Comes with Windows based PC software, including:

PID parameter selection program (recommended stability settings based on excitation system type)

Read and write all parameters

Real time monitoring (12 parameters including voltage, current, frequency, power factor, etc.)

Remote control (excitation, mode switching, set point adjustment)