[0028] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other if there is no conflict. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.
[0029] Reference figure 1 The gas turbine generator set of the present invention is a small gas turbine generator set, which as a whole includes a gas turbine 2, a reducer 3, a generator G and a separately excited DC motor XM arranged on the base 1. In this preferred embodiment, the generator G uses a brushed generator, and the separately excited DC motor XM uses a standard separately excited DC motor. The gas turbine 2 is coaxially installed and connected with the generator G through the reducer 3. Separately excited DC motor XM and generator G are installed coaxially with the same rated speed.
[0030] Reference figure 2 with image 3 The starting and excitation system of the gas turbine generator set of the preferred embodiment of the present invention uses a standard separately excited DC motor as the starter of a small gas turbine generator set. After the start is completed, the separately excited DC motor switches to the DC generator working mode. The direct current generated by the motor provides power to the automatic excitation device AVR while providing excitation to the generator. figure 2 The principle diagram of the main circuit of the starting and excitation system of the gas turbine generator set of the present invention is shown in the figure, wherein each contactor is shown as a main contact. image 3 Shown in figure 2 The schematic diagram of the corresponding secondary circuit, where each contactor is shown as an auxiliary contact.
[0031] In this preferred embodiment, the starting and excitation system of the gas turbine generator set includes: DC switching power supply PS1, starting control module 100, automatic excitation device AVR, separately excited DC motor XM, generator G, first contactor KM1, second contact KM2 and the third contactor KM3. The DC switching power supply PS1 is connected to the excitation winding of the separately excited DC motor XM through the first contactor KM1, and is used to provide the excitation current for the separately excited DC motor XM during the start of the unit. The starting control module 100 is connected to the main winding of the separately excited DC motor XM through the second contactor KM2, and is used to provide a starting current for the separately excited DC motor XM during the start of the unit. The output end of the automatic excitation device AVR is connected to the excitation winding of the separately excited DC motor XM through the first contactor KM1, which is used to provide excitation for the separately excited DC motor XM after the unit is started. The main winding of the separately excited DC motor XM is connected to the excitation winding of the generator G through the normally open main contact of the third contactor KM3, and also connected to the input of the automatic excitation device AVR through the second contactor KM2. The separately excited DC motor XM is used as an exciter to provide excitation current for generator G after the unit is started, and at the same time to provide power to the automatic excitation device AVR.
[0032] The invention uses the separately excited DC motor XM as the starter of the gas turbine generator set. After the start is completed, the separately excited DC motor XM serves as the exciter to provide excitation for the generator G while supplying power to the automatic excitation device AVR, which can effectively reduce the similar The installation space of the unit is simpler than the traditional excitation scheme structure and circuit, which can reduce the cost.
[0033] Further, the first contactor KM1 includes two normally open main contacts and two normally closed main contacts, as the system excitation switching control contactor. The output end of the DC switching power supply PS1 is respectively connected to both ends of the excitation winding of the separately excited DC motor XM through the two normally open main contacts of the first contactor KM1. The two output terminals of the automatic excitation device AVR are respectively connected to the two ends of the excitation winding of the separately excited DC motor XM through the two normally closed main contacts of the first contactor KM1.
[0034] Further, a demagnetization resistor R1 is also connected in series between the output terminal of the DC switching power supply PS1 and the normally open main contact of the first contactor KM1. The demagnetization resistor R1 is used to control the starting excitation current of the separately excited DC motor XM, so that the separately excited DC motor XM can start smoothly. In this embodiment, the resistance value of the demagnetization resistor R1 is equal to the voltage of the DC switching power supply PS1 divided by the rated excitation current of the separately excited DC motor XM minus the resistance of the excitation winding of the separately excited DC motor XM.
[0035] A circuit composed of three freewheeling diodes D1, D2, and D3 is connected in parallel at both ends of the excitation winding of the separately excited DC motor XM. The three diodes are used to absorb the separately excited DC motor XM when the separately excited DC motor XM stops. The residual current on the field winding, three diodes in series can effectively share the transient reverse excessive induced voltage and improve the reliability of the loop.
[0036] Further, the second contactor KM2 includes two normally open main contacts and two normally closed main contacts, which serve as system start-up and excitation switching contactors. The starting control module 100 is connected to the main winding of the separately excited DC motor XM through the two normally open main contacts of the second contactor KM2. The input end of the automatic excitation device AVR is connected to the main winding of the separately excited DC motor XM through the two normally closed main contacts of the second contactor KM2.
[0037] Further, the starting control module 100 includes a three-phase full-bridge rectifier module 101, a thyristor power controller 102, and a DC reactor 103. The three-phase full-bridge rectifier module 101 is connected to the AC mains and is used for rectifying and converting the AC into DC. The thyristor power controller 102 is connected in series with the three-phase full-bridge rectifier module 101 for controlling the starting time and the voltage rising slope during the starting of the unit. The DC reactor 103 is connected in series with the thyristor power controller 102, and its other end is connected to the two normally open contacts of the second contactor KM2, which is used to eliminate the output ripple of the starting control module 100 and suppress harmonics.
[0038] In this preferred embodiment, the third contactor KM3 includes a set of normally open main contacts and a set of normally closed main contacts, which serve as the de-excitation switch of the generator G. The normally closed main contact of the third contactor KM3 is connected in series with the demagnetization resistance R2 of the generator G to both ends of the excitation winding of the generator G as the demagnetization switch of the generator G. At the same time, the normally open main contact of the third contactor KM3 is used to disconnect the separately excited DC motor XM and the generator G during the starting process, which can disconnect the connection between the separately excited DC motor XM and the generator G to ensure effective and reliable Start. The third contactor KM3 will act after the start is completed. Its normally open main contact is closed and conducted at the same time the normally closed main contact is disconnected. The output of the separately excited DC motor XM can be supplied to the excitation winding of the generator G to realize the control of the generator. Excitation of G. When the unit is stopped, the third contactor KM3 loses power, and the normally closed main contact that is separated during operation is closed again. The excitation winding of the generator G is conducted through KM3 and the demagnetization resistor R2 to realize the demagnetization of the generator G.
[0039] Further, a series circuit of a de-excitation resistor R2 and the normally closed main contact of the third contactor KM3 is connected in parallel at both ends of the excitation winding of the generator G. The de-excitation resistor R2 can quickly absorb the magnetic energy of the excitation winding of the generator G when the generator G cuts off the excitation circuit, slow down the rotor current change speed of the generator G, reduce the rotor self-induced electromotive force, and thereby suppress the rotor overvoltage and demagnetization. The automatic excitation device AVR is connected to the voltage transformer PT and/or current transformer CT on the output circuit of the generator G. This structure can realize the automatic excitation device AVR monitors the voltage and current of the generator G through the voltage transformer PT and the current transformer CT, and then automatically controls the output current through the measured voltage and current, thereby controlling the output of the exciter XM. In turn, the output voltage, active and reactive power of the generator G are controlled.
[0040] The starting and excitation system of the gas turbine generator set of the present invention also includes a control panel and an instrument for the operator to set control parameters and input commands. In addition, it also includes a control system, which is used to issue a start command, an excitation command, and control the action of each contactor.
[0041] The present invention also provides a method for starting and excitation of a gas turbine generator set, which is performed by using the above-mentioned starting and excitation system for a gas turbine generator set, and the method includes:
[0042] During the start of the unit, the DC switching power supply PS1 provides excitation current for the separately excited DC motor XM, and the starting control module 100 provides the starting current for the separately excited DC motor XM;
[0043] After the unit is started, the separately-excited DC motor XM and generator G are driven by the gas turbine through a reducer to achieve coaxial rated speed operation. The automatic excitation device AVR provides excitation for the separately-excited DC motor XM, and then the output DC power of the separately-excited DC motor XM Provide excitation current for generator G, and at the same time provide power supply for automatic excitation device AVR. At this time, the separately excited DC motor XM is transformed from a motor to an exciter to provide excitation for generator G.
[0044] Furthermore, during the start-up of the unit,
[0045] After receiving the start command, the first contactor KM1 and the second contactor KM2 are controlled to act, and the third contactor KM3 is prohibited from acting. The control loop of the third contactor KM3 is connected in series with the normally closed auxiliary contact of the first contactor KM1. At this point, the DC switching power supply PS1 provides the excitation current for the separately excited DC motor XM through the series demagnetization resistor R1, and the AC mains provides the starting current for the separately excited DC motor XM via the starting control module 100, so that the separately excited DC motor XM starts;
[0046] When the separately-excited DC motor XM drives the gas turbine generator set to complete the start, it receives a disconnect start command. At this time, the gas turbine drives the separately-excited DC motor XM and the generator G to achieve coaxial rated speed operation.
[0047] After receiving the excitation command, the third contactor KM3 is controlled to be turned on, the first contactor KM1 and the second contactor KM2 are forbidden to operate, and the third contactor KM1 and the second contactor KM2 are connected in series in the control loop. The normally closed auxiliary contact of the contactor KM3 makes the separately excited DC motor XM switch from the motor mode to the exciter working mode. The voltage generated by the residual magnetic field of the separately excited DC motor XM starts the automatic excitation device AVR, and the automatic excitation device AVR The output provides excitation current to the excitation winding of the separately excited DC motor XM, and the output DC power of the separately excited DC motor XM provides the excitation current for the generator G, and at the same time provides the power supply for the automatic excitation device AVR.
[0048] After the unit is started, the automatic excitation device AVR simultaneously monitors the voltage and current of the generator G through the voltage transformer PT and current transformer CT on the output circuit of the generator G, and automatically controls the power generation through the measured voltage and current The output voltage, active power, and reactive power of generator G are used to realize the power generation control of the unit.
[0049] A specific implementation process of the starting and excitation method of the present invention is given below.
[0050] During the starting process, the gas turbine generator set starting and excitation system of the present invention receives the starting command issued by the control system. At this time, KM1 and KM2 act, and KM3 is prohibited from acting, so that the two normally open main contacts of KM1 are closed and the two normally closed The main contact is disconnected, the two normally open main contacts of KM2 are closed, and the two normally closed main contacts are disconnected. In this state, the DC switching power supply PS1 is connected in series with the demagnetization resistor R2 to provide excitation to the separately excited DC motor XM via KM1, and the external 380VAC AC power passes through the three-phase full-bridge rectifier module 101, the thyristor power controller 102 and the DC reactor 103 output is given to the separately excited DC motor XM via KM2, and the starting time and the slope of the voltage rise are set in the thyristor power controller 102 to control the starting of the separately excited DC motor XM. After the separately excited DC motor XM is started, because it is coaxially connected with the generator G, and the generator G and the gas turbine are installed coaxially through the reducer, it will drive the gas turbine to start and rotate. After the start is completed, the control system disconnects the start command, and the unit reaches the rated speed through the gas turbine output. At this time, the starter motor XM and the generator G are driven by the gas turbine through the reducer to achieve coaxial rated speed operation.
[0051] During the excitation process, the system receives the excitation command sent by the control system, KM3 acts, KM1 and KM2 are forbidden to act, so that the normally open main contact of KM3 is normally closed and the main contact is disconnected, and the two normally open main contacts of KM1 are disconnected. Open, the two normally closed main contacts are closed, the two normally open main contacts of KM2 are open, and the two normally closed main contacts are closed. At this time, the separately excited DC motor XM turns to the exciter working mode, and the voltage generated by the residual magnetic field of the separately excited DC motor XM starts the automatic excitation device AVR through the normally closed contact of KM2. The automatic excitation device AVR provides excitation to the separately excited DC motor XM through the normally closed contacts of KM1, and the output voltage of the separately excited DC motor XM gradually increases. The output power of the separately excited DC motor XM provides excitation to the generator G and at the same time to the automatic excitation device AVR provides power supply (it can be understood as a self-shunt excitation system using the output of the exciter). The output voltage of the exciter is not high and just within the tolerance of the AVR, thus eliminating the need for the excitation transformer in the traditional brushless generator excitation system . The automatic excitation device AVR also monitors the voltage and current of the generator G through the voltage transformer PT and current transformer CT, and automatically controls the output voltage, active and reactive power of the generator through the measured voltage and current to realize the generation control of the unit .
[0052] The above are only preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc., made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
