Abstract In order to further improve the stability of the power grid operation and improve the power quality of the power grid, a primary frequency modulation online test function was added to the Dongfang-Mitsubishi M701DA gas turbine control system, and this function was analyzed. Keywords primary frequency modulation; online testing; improvement
CLC classification number TK477 Document identification code A Article number 1673-9671-(2012)071-0160-02
1 Overview
The combined cycle unit of Jiangsu Huadian Qishuyan Co., Ltd. consists of a gas turbine, a steam turbine, a waste heat boiler and two generators. The gas turbine is model M701DA designed by Japan's Mitsubishi Heavy Industries. It is a dry, low-NOX emission heavy-duty gas turbine manufactured by Dongfang Turbine Factory. The gas turbine consists of a 19-stage compressor, 18 premixed low-NOX burners and a 4-stage turbine. The gas turbine has a rated load of 144 MW under standard operating conditions.
At present, the daily management of the primary frequency regulation function of the generator set by the power grid only uploads a "generator set primary frequency regulation input/out" signal to the provincial regulation EMS system for monitoring. It cannot be monitored like the provincial regulation EMS system. Like the AGC function of the generator set, it provides online real-time monitoring of the primary frequency regulation function of the generator set. The "generator unit primary frequency regulation input/off" signal may not accurately reflect the commissioning and control quality of the generator unit's primary frequency regulation.
In order to further improve the stability of the power grid operation, improve the power quality of the power grid, and strengthen the power grid company's supervision and management of primary frequency regulation of grid-connected units, the M701DA gas turbine control system adds a primary frequency regulation online test function. Reliable data on the primary frequency regulation capacity of the unit obtained through online testing of the unit's primary frequency regulation can make a more accurate prediction of the total load of the unit's primary frequency regulation in the power grid, providing a reference for the safe and stable operation of the power grid.
2 Function improvements
In order to meet the requirements of primary frequency modulation online testing, the control system adds a hard wiring point.
1) One frequency modulation entry test;
2) One frequency modulation load increase test;
3) One frequency modulation load reduction test;
4) One frequency modulation characteristic parameter test;
5) One frequency modulation exit test;
The signal contact relationship is shown in Figure 1.
Figure 1 Simplified diagram of the signal connection between the provincial regulation and the control system
"Primary frequency modulation enters test" is sent by the provincial regulation. This signal switches the primary frequency modulation function of the control system to the test mode. The primary frequency regulation function of the power plant exits actual operation and no longer responds to changes in the grid cycle.
After the control system receives the "increased load test", the primary frequency modulation function automatically generates a maximum negative frequency difference of 0.1083Hz, and the unit load response is increased to test the performance of the unit's primary frequency modulation and load increase.
After the control system receives the "load reduction test", the primary frequency modulation function automatically generates a maximum forward frequency difference of 0.1083Hz, and the unit load response is reduced to test the unit's primary frequency modulation load reduction performance.
"Primary frequency modulation exit test" is sent by the provincial regulator. This signal switches the primary frequency modulation function of the control system to the normal mode, and the primary frequency modulation function of the power plant is put into actual operation again. After a frequency modulation load increase or decrease test is completed, the signal can be sent out by the provincial modulator.
The "primary frequency modulation characteristic parameter test" is sent from the provincial regulation to the power plant control system to conduct a test of the frequency modulation characteristic function. Obtain the primary frequency modulation capability of the unit.
"Frequency" is the grid frequency value used in primary frequency regulation of the unit. When performing characteristic parameter testing, the signal is a simulated frequency value.
"Primary frequency regulation load command" is the load command response generated by the unit to the current frequency difference value.
When testing the characteristic parameters of the control system, the signal is the primary frequency modulation load command value of the control system. According to the functional relationship between the frequency difference and the primary frequency modulation load command, the primary frequency modulation characteristic function set in the control system can be obtained, and the primary frequency modulation dead value can be obtained. Area, maximum amplitude, inequality and other parameters.
The flow chart of the online test function in the control system is shown in Figure 2.
When a load increase or decrease command is received, the primary frequency modulation function automatically generates a maximum forward frequency difference of 0.1083HZ, and the unit load responds by increasing. When a load reduction command is received, the unit load responds by decreasing. Small, test the load increasing and decreasing performance of one frequency modulation.
3 Test results after function improvement
3.1 Increased load test
When the provincial regulator issues an increased load test command, the primary frequency modulation test logic automatically switches the frequency difference To the maximum forward frequency difference value of 0.1083 HZ, one frequency modulation generates a load command of 5,625 MW. 45 seconds after the load increase command is issued, the test logic automatically restores the maximum deviation of 0.1083 Hz to zero, the load command generated by primary frequency modulation returns to zero, and the load increase test ends. The curve is shown in Figure 3.
Figure 3 Load increase test
3.2 Load reduction test
When the provincial regulator issues a load reduction test command, the primary frequency regulation test logic automatically switches the frequency difference to The maximum forward frequency difference value is -0.1083 HZ, and one frequency modulation generates a load command of -5,625 MW. 45 S after the load reduction command is issued, the test logic automatically restores the maximum deviation of -0.1083 Hz to zero, the load command generated by primary frequency modulation returns to zero, and the load reduction test ends. The curve is shown in Figure 4.
3.3 Primary frequency modulation characteristic parameter test
After the provincial dispatcher sends out the "primary frequency modulation characteristic parameter test", the dispatcher can remotely obtain the primary frequency modulation characteristic function in the gas turbine control system and the test results Consistent with the control system logic.
Figure 4 Load reduction test
4 Conclusion
By adding a primary frequency modulation online test function to the control system, the provincial regulator can obtain primary frequency modulation performance data and pass the primary frequency modulation test function. Testing of frequency regulation parameters, provincial regulation can obtain the primary frequency regulation characteristic parameters in the gas turbine control system, and obtain parameters such as primary frequency regulation dead zone, droop, maximum amplitude, etc., to meet the power grid's supervision and management of primary frequency regulation of grid-connected units.
References
[1] Dongfang Steam Turbine Co., Ltd., Primary Frequency Modulation Test Procedure [M].
[2] Mitsubishi Heavy Industries, Gas Turbine Control System Logic [M].