An excitation device for optimizing the dynamic response performance of a generator

Abstract

The present invention discloses an excitation device for optimizing the dynamic response performance of a generator, which includes: series resonance, a voltage and current detection unit, a thyristor voltage regulation unit, a magnetically coupled rectifier transformer, an automatic voltage regulator, a starting magnetizing unit, a BOOST excitation unit, and a rectifier diode. The advantages are: on the one hand, during the starting process of the generator, especially when the residual magnetism of the rotor disappears due to long-term non-startup, the generator can be magnetized for a short time by the starting magnetizing unit, thereby providing an initial voltage for the generator resonance voltage building, greatly improving the reliability of the nuclear power diesel generator set. On the other hand, when the generator is suddenly loaded, the energy provided by the magnetically coupled rectifier transformer to the excitation system is forcibly increased due to the increase in the current component. At the same time, the BOOST excitation unit can quickly increase the terminal voltage at both ends of the exciter, which can not only shorten the response time of voltage recovery after the sudden load, but also suppress the large voltage fluctuations, thereby improving the dynamic response performance of the system.

Description

Technical Field

[0001] The present invention relates to a generator excitation system, in particular to an excitation device for optimizing the dynamic response performance of a generator, and belongs to the technical field of power generation equipment. Background Art

[0002] The generators used in diesel generator sets of nuclear power plants are an important component to ensure the safe operation of nuclear power plants. The loads they carry are mainly composed of electric pumps, fans, valves, etc. The sudden addition and removal of these inductive loads will have a certain impact on the stability of the terminal voltage of the generator, especially small generators.

[0003] Small generator sets used in nuclear power mostly adopt self-excitation mode, and the excitation power source is mostly taken from the generator terminal voltage. The generator relies entirely on the residual magnetism of the rotor winding in the initial stage of voltage building. Small diesel generator sets in nuclear power plants are often started once a month or even longer. There is a possibility that the residual magnetism of the generator disappears and the voltage cannot be built normally, which has a negative impact on the reliability of the unit and the safety of the nuclear power plant.

[0004] During the loading process of small nuclear power generator sets, the load power accounts for a large proportion of the rated power of the unit, and the adjustment ability of the generator excitation system is limited, resulting in large fluctuations in the generator terminal voltage and a long recovery time.

[0005] The existing generator excitation system's strong excitation link uses a large-capacity current transformer to absorb the generator end current for strong excitation regulation when the generator is suddenly overloaded or short-circuited. The intensity or proportion of the regulation is not controlled by the voltage regulator, which can easily cause a large overshoot of the generator end voltage. Summary of the Invention

[0006] The purpose of the present invention is to propose an excitation device that optimizes the dynamic response performance of the generator, improve the reliability of the excitation system of a small generator, shorten the response time of voltage recovery after a sudden load is added to the generator, effectively suppress large voltage fluctuations, and improve the dynamic response performance of the system.

[0007] According to the technical solution of the present invention, an excitation device for optimizing the dynamic response performance of a generator includes: series resonance, a voltage and current detection unit, a thyristor voltage regulation unit, a magnetically coupled rectifier transformer, an automatic voltage regulator, a starting magnetizing unit, a BOOST excitation unit, and a rectifier diode; the generator output voltage is connected to the magnetically coupled rectifier transformer through series resonance, and the generator output current and the series resonance output voltage are coupled in the magnetically coupled rectifier transformer; the secondary side of the magnetically coupled rectifier transformer is output to the rectifier diode after passing through the thyristor voltage regulation link, the output end of the rectifier diode is connected to the input end of the BOOST excitation unit, and the output end of the BOOST excitation unit and the starting magnetizing unit are connected in parallel and output to the exciter stator; the excitation voltage is input to the generator rotor through the rotating rectifier diode by the excitation rotor; the generator stator output voltage is adopted to the automatic voltage regulator through a voltage and current transformer, and the automatic voltage regulator controls the BOOST excitation unit and the thyristor voltage regulation unit according to the output voltage and current values ​​to improve the voltage dynamic steady-state performance.

[0008] The starting magnetizing unit consists of a diode, an energy storage capacitor, a current limiting resistor and a normally open contact. 10 seconds (the time is adjustable) after the generator receives the start command, if the generator cannot successfully build voltage due to the disappearance of residual magnetism, the automatic voltage regulator will send a signal to close the normally open contact so that the energy storage capacitor charges the exciter stator, thereby improving the reliability of the generator voltage building.

[0009] When the generator is running, if the voltage across the energy storage capacitor is lower than a certain value, the normally open contacts of the magnetizing unit close the excitation unit to charge the energy storage capacitor.

[0010] The main circuit of the BOOST excitation unit consists of an inductor, IGBT, diode and capacitor. When the generator is operating normally, the IGBT is always in the off state and the BOOST excitation unit is in the exit state. When the generator load suddenly increases, the IGBT starts working to increase the stator voltage of the exciter and shorten the response time of voltage recovery.

[0011] The thyristor voltage regulating unit consists of a thyristor and a current limiting resistor, which are connected in series and then connected to the three-phase winding on the secondary side of the magnetically coupled rectifier transformer. Each phase winding is independently connected to a thyristor and a current limiting resistor, and they are not shared with each other.

[0012] The magnetic coupling rectifier transformer combines the primary side high voltage and current through magnetic coupling and then induces them to the secondary side, thereby avoiding direct electrical connection between the primary side and the secondary side and improving the safety of the excitation system.

[0013] The automatic voltage regulator detects the voltage and current of the generator, and uses a digital PID control method to control the thyristor conduction angle and IGBT duty cycle to achieve dynamic and steady-state regulation of the generator output voltage.

[0014] The advantages of the present invention are:

[0015] The self-excited excitation system contains energy storage capacitors. When the residual magnetism of the nuclear power diesel generator set disappears due to long-term non-use, the stator of the excitation machine is charged through the energy storage capacitors, thereby improving the reliability of the nuclear power diesel generator set pressure.

[0016] The automatic voltage regulator can effectively control the BOOST link and adjust the duty cycle of the IGBT according to the size of the generator terminal voltage. It can not only shorten the response time of voltage recovery after a sudden load, but also suppress large voltage fluctuations and improve the dynamic response performance of the system.

[0017] The excitation power source is effectively isolated by a magnetically coupled rectifier transformer, effectively avoiding direct electrical connection between the primary side of the generator and the excitation control system, thereby improving the safety of the system.

[0018] The thyristor voltage regulating unit synchronously regulates the output three-phase voltage of the magnetically coupled rectifier transformer, which will expand the voltage adjustment range of the generator and improve the stability of the output DC voltage after the rectifier diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in further detail below with reference to the accompanying drawings.

[0020] Figure 1 This is the excitation system block diagram of the present invention

[0021] Figure 2 This is the overall circuit schematic diagram of the present invention DETAILED DESCRIPTION

[0022] like Figure 1 As shown, the present invention includes: series resonance, voltage and current detection unit, thyristor voltage regulation unit, magnetic coupling rectifier transformer, automatic voltage regulator, starting magnetizing unit, BOOST excitation unit and rectifier diode; the generator output voltage is connected to the magnetic coupling rectifier transformer through series resonance, and the generator output current and the series resonance output voltage are coupled in the magnetic coupling rectifier transformer; the secondary side of the magnetic coupling rectifier transformer is output to the rectifier diode after passing through the thyristor voltage regulation link, and the output end of the rectifier diode is connected to the input end of the BOOST excitation unit. The output end of the BOOST excitation unit and the starting magnetizing unit are connected in parallel and output to the exciter stator; the excitation voltage of the exciter rotor is input to the generator rotor after passing through the rotating rectifier diode; the generator stator output voltage is adopted to the automatic voltage regulator through the voltage and current transformer, and the automatic voltage regulator controls the BOOST excitation unit and the thyristor voltage regulation unit according to the output voltage and current values ​​to improve the voltage dynamic steady-state performance.

[0023] like Figure 2As shown, each phase of the series resonant unit consists of an inductor and a capacitor. Pin 1 of inductor L1 is connected to the generator terminal voltage A, pin 1 of inductor L2 is connected to the generator terminal voltage B, and pin 1 of inductor L3 is connected to the generator terminal voltage C. Pin 2 of the inductor is connected to pin 1 of capacitors C1, C2, and C3, respectively, and to pin 3 of T1, T2, and T3, respectively. Pin 2 of C1, C2, and C3 is short-circuited, and pin 4 of T1, T2, and T3 is short-circuited and grounded. Pins 1 and 2 of the magnetically coupled rectifier transformers T1, T2, and T3 are connected in series to the generator output voltage main circuit. Pin 5 of the secondary output of T1, T2, and T3 is connected to terminals A, B, and C of the rectifier bridge Z1, respectively, and is also connected in parallel to pin 1 of the current-limiting resistor of the thyristor voltage regulator unit. Pin 6 of T1, T2, and T3 is short-circuited and grounded.

[0024] like Figure 2 As shown, the A pins of the thyristors VT1, VT2, and VT3 in the thyristor voltage regulating unit are connected to the 2 pins of R1, R2, and R3 respectively, and are connected in parallel to the A1, A2, and A3 pins of the UC1 voltage regulator. The G pins of the thyristors VT1, VT2, and VT3 are connected to the G1, G2, and G3 of UC1 respectively. UC1 controls the conduction angles of the thyristors VT1, VT2, and VT3 through G1, G2, and G3. The K pins of the thyristors are short-circuited with each other and then grounded. The thyristor unit adjusts the output voltage of the generator by controlling the conduction angles of VT1, VT2, and VT3.

[0025] like Figure 2 As shown, the output of the rectifier bridge Z1 is connected to the input of the strong excitation BOOST unit through terminals X1 and X2, pin 1 of the inductor L4 is connected to pin A of the diode VD1, and is connected in parallel to the collector C of the IGBT, the gate G of the IGBT is connected to G4 of UC1, and the emitter E is connected to E4 of UC1 through terminal X2. The K pin of the diode VD1 is connected to pin 1 of the capacitor C4 as the positive electrode of the BOOST output, and the 2 pin of the capacitor C4 is connected to the collector E of the IGBT as the negative electrode of the BOOST output. The BOOST unit does not participate in voltage regulation when the load is not suddenly increased or the output is short-circuited.

[0026] like Figure 2 As shown, the output of the strong excitation BOOST unit is used as the input of the starting magnetizing unit. When the generator is in normal operation and non-starting state, the starting magnetizing unit K3 is turned on, the K pin of VD2 is connected to the 33-node of the switch K3, the 34-node of K3 is connected to the 1-pin of the adjustable resistor R4, the 2-pin of R4 is connected to the 1-pin of the energy storage capacitor C5, and the 2-pin is connected in parallel to the negative pole of the excitation voltage. The positive pole of the starting magnetizing unit output is connected to the exciter stator F+, and the negative pole of the output is connected to the exciter stator F-.

[0027] like Figure 2 As shown, the primary side of detection current transformer T4 is connected in series with the generator output phase V. Secondaries S1 and S2 are connected to terminals I1 and COM of the UC1 voltage regulator, respectively. UC1's voltage measurement is derived from the secondary side of voltage transformer T5. T5's primary side is connected to the generator's three-phase output phases U, V, and W, respectively. Secondaries a, b, and c are connected to terminals Ua, Ub, and Uc of UC1. UC1 accepts digital starting signals, boost, and voltage buildup signals. Furthermore, magnetizing switch coil K3 is controlled to magnetize the exciter stator windings based on whether the generator successfully builds voltage during the starting process. PI regulation of the thyristors and IGBTs is implemented based on fluctuations in the generator's voltage and current, improving the system's excitation dynamic and steady-state performance.

[0028] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An excitation device for optimizing the dynamic response performance of a generator, characterized in that: include: Series resonance, voltage and current detection unit, thyristor voltage regulation unit, magnetic coupling rectifier transformer, automatic voltage regulator, starting magnetization unit, BOOST excitation unit and rectifier diode; the generator output voltage is connected to the magnetic coupling rectifier transformer through series resonance, and the generator output current and the series resonance output voltage are coupled in the magnetic coupling rectifier transformer; The secondary side of the magnetic coupling rectifier transformer is output to the rectifier diode after passing through the thyristor voltage regulation link. The output end of the rectifier diode is connected to the input end of the BOOST strong excitation unit. The output end of the BOOST strong excitation unit is connected in parallel with the starting magnetizing unit and then output to the exciter stator; the exciter rotor inputs the excitation voltage to the generator rotor after passing through the rotating rectifier diode; the generator stator output voltage is sampled by the voltage and current transformer and then transmitted to the automatic voltage regulator. The automatic voltage regulator controls the BOOST strong excitation unit and the thyristor voltage regulation unit according to the output voltage and current values ​​to improve the voltage dynamic and steady-state performance; the starting magnetizing unit is composed of a diode, an energy storage capacitor, a current limiting resistor and a normally open contact. Ten seconds after the generator receives the start command, if the generator fails to successfully build voltage due to the loss of residual magnetism, the automatic voltage regulator will send a signal to close the normally open contacts, allowing the energy storage capacitor to charge the exciter stator, improving the reliability of the generator voltage building. During the operation of the generator, if the voltage across the energy storage capacitor falls below a certain value, the normally open contacts will close and the excitation unit will charge the energy storage capacitor. The main circuit of the BOOST excitation unit consists of an inductor, IGBT, diode, and capacitor. During normal operation of the generator, the IGBT is always in the off state, and the BOOST excitation unit is in the off state. In the event of a sudden increase in the generator load, the IGBT will start to work to increase the exciter stator voltage, shortening the voltage recovery response time. The thyristor voltage regulation unit consists of a thyristor and a current-limiting resistor. The thyristor and the current-limiting resistor are connected in series to the three-phase winding on the secondary side of the magnetically coupled rectifier transformer. Each phase winding is independently connected to a thyristor and a current-limiting resistor, and they are not shared with each other. The thyristor synchronously adjusts the output voltage of the magnetically coupled rectifier transformer, which can greatly widen the voltage adjustment range of the generator terminal. Especially in the case of sudden load unloading of the generator, the three groups of thyristor voltage regulation devices operate simultaneously, improving the dynamic response performance of the excitation system.

2. The excitation device for optimizing the dynamic response performance of a generator according to claim 1, characterized in that: The magnetically coupled rectifier transformer combines the high voltage and current on the primary side and then senses them to the secondary side through magnetic coupling, avoiding direct electrical connection between the primary and secondary sides and improving the safety of the excitation system.

3. The excitation device for optimizing the dynamic response performance of a generator according to claim 1, characterized in that: The automatic voltage regulator detects the voltage and current of the generator, and uses the digital PID control method to control the thyristor conduction angle and IGBT duty cycle to achieve dynamic and steady-state regulation of the generator output voltage.

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