CN204928171U - A sub-harmonic reactive power generating device - Google Patents

Abstract

The utility model relates to a power grid technology field discloses an idle generating device of subharmonic, including the control unit and valves unit, wherein: the control unit for obtaining generating set's rotational speed deviation signal, and calculating according to this rotational speed deviation signal and restrain the required inferior harmonic current of subsynchronous oscillation, gain merit in proper order - idle decoupling zero and pulsewidth modulation based on dq transform pair grid voltage and required inferior harmonic current, signal driver after making uses simultaneously the valves unit, so that the inferior harmonic current that the valves unit sent is idlely, the valves unit is used for send time harmonic current under the control unit's the drive to the inferior harmonic current that will send pours into the electric wire netting into with idle form. The utility model discloses an independent control after active component among the electric power system and reactive component decoupling zero, is carried out respectively to the dq transform to it is idle to ensure that the subharmonic that sends is, has restrained subsynchronous oscillation under the idle mode of perseverance better.

Description

A sub-harmonic reactive power generating device

technical field

The utility model relates to the technical field of power grids, in particular to a sub-harmonic reactive power generating device.

Background technique

With the continuous expansion of the power grid system, the demand for ultra-high voltage direct current transmission and large-capacity generator sets is also increasing. In order to reduce line transmission loss, controllable series compensation is commonly used to increase the grid-side voltage. Although it brings huge economic benefits, but It also brings new troubles to the safe and stable operation of the generator set, and the subsynchronous oscillation of the power system is one of the more serious problems.

For this reason, many measures to suppress the subsynchronous oscillation of generators have been proposed, and the most used in the prior art are: bypass damping filter and static blocking filter composed of passive components; SVC device with power electronic devices added. However, these technologies have shortcomings such as slow response speed and poor tracking ability, and the ability to generate sub-harmonics is limited, so they cannot fundamentally solve the existing problems. In view of the shortcomings of the existing technology, such as slow response speed and poor tracking performance, a new solution needs to be proposed.

Utility model content

The purpose of the utility model is to provide a sub-harmonic reactive power generating device, which is used to realize the purpose of generating sub-harmonic current to suppress sub-synchronous oscillation.

In order to achieve the above purpose, the utility model provides a sub-harmonic reactive power generating device, including a control unit and a valve group unit, wherein: the control unit is used to obtain the speed deviation signal of the generator set, and according to the speed deviation signal Calculate the sub-harmonic current required to suppress the sub-synchronous oscillation, then perform active-reactive decoupling and pulse width modulation on the grid voltage and the required sub-harmonic current based on the dq transformation, and drive the valve with the modulated signal group unit, so that the sub-harmonic current issued by the valve group unit is reactive; Current is injected into the grid in the form of reactive power.

Preferably, it also includes a cabinet-type power supply unit, which is used to provide corresponding working power for the control unit and the valve group unit, and the power supply unit further includes: a UPS module, used to provide uninterrupted AC power supply; a power isolation module, which is connected to the UPS module and the low-voltage power distribution module, and is used to rectify the uninterrupted AC power provided by the UPS module, and provide the rectified power to the low-voltage power distribution module; and the A low-voltage power distribution module, which is connected to the control unit and the valve group unit, and is used for distributing working power to the control unit and the valve group unit.

Preferably, the control unit is a cabinet-type structure, including: an industrial computer for realizing interface display and operation; a system control module, which communicates with the industrial computer, and is used for calculating the required time for suppressing subsynchronous oscillation according to the speed deviation signal. The sub-harmonic current; and the device control module, which communicates with the industrial computer and is located downstream of the system control module, and is used to perform active-inactive sequentially on the grid voltage and the required sub-harmonic current based on dq transformation Power decoupling and modulation, and the modulated signal is used to drive the valve group unit, so that the sub-harmonic current sent by the valve group unit is reactive.

Preferably, the device control module includes: a phase-locked loop module for tracking and phase-locking the grid voltage; a voltage loop module for calculating the deviation between the DC side voltage reference value and the DC side voltage feedback value of the valve group unit signal, and perform PI adjustment and phase transformation on the deviation signal, and output the active component Two Park transformation modules, one of which is located downstream of the phase-locked loop 131 module, is used to perform dq transformation on the grid voltage to obtain the active component of the grid voltage and The other is used to perform dq transformation on the required sub-harmonic current to obtain the active component of the required sub-harmonic current and reactive component Active-reactive current decoupling control module, which is located downstream of the Park transformation module, is used to decouple all active components and reactive components obtained above, and output voltage vector The Park inverse conversion module, which is located downstream of the active-reactive current decoupling control module, is used to convert the voltage vector Transform to get a three-phase modulation signal and And the SPWM modulation module, which is located in the downstream of the Park inverse transformation module, for three-phase modulation signal and Perform SPWM modulation to obtain a corresponding PWM driving signal to drive the valve group unit.

Preferably, the device control module further includes a carrier phase shift module located downstream of the SPWM modulation module, for performing carrier phase shift processing on the PWM driving signal.

Preferably, the valve group unit is a chain structure corresponding to a three-phase three-wire power grid, and several IEGT phase modules are connected in series in each phase.

Preferably, the IEGT phase module includes: a switching device IEGT1 and a switching device IEGT2, the switching device IEGT1 is connected in parallel with a freewheeling diode D1, the switching device IEGT2 is connected in parallel with a freewheeling diode D2, the switching device IEGT1 and the switching device IEGT2 are connected in series, and the middle The connection end leads out to be the output end.

Preferably, the IEGT phase module further includes a buffer absorption circuit, the buffer absorption circuit includes two series connected inductors L1, L2, a resistor R, a diode D3 and a capacitor C, the positive terminal of the diode D3 is connected to the inductor L2, and the negative terminal of the diode D3 It is connected to one end of the resistor R, and the other end of the resistor R is connected to the inductor L1; the negative end of the diode D3 is also connected to one end of the capacitor C, and the other end of the capacitor C is connected to the negative end of the power supply.

Preferably, it also includes: a heat dissipation unit, used for heat dissipation of the valve group unit.

Preferably, the heat dissipation unit adopts a water cooling system.

Through the above-mentioned technical scheme, the beneficial effect of the utility model is: the utility model adopts dq transformation, after decoupling the active component and the reactive component in the electric power system, carry out independent control respectively, to ensure that the sub-harmonic waves emitted are all reactive , the subsynchronous oscillation is better suppressed in constant var mode. In general, the sub-harmonic reactive power generating device of the present invention has the advantages of fast response speed, wide adjustable range, large capacity, etc., and can well suppress the sub-synchronous oscillation phenomenon in the power system.

Other features and advantages of the present utility model will be described in detail in the following specific embodiments.

Description of drawings

The accompanying drawings are used to provide a further understanding of the utility model, and constitute a part of the description, together with the following specific embodiments, are used to explain the utility model, but do not constitute a limitation to the utility model. In the attached picture:

Fig. 1 is a structural schematic diagram of a sub-harmonic reactive power generating device in an embodiment of the present invention, and simultaneously illustrates the connection between the sub-harmonic reactive power generating device and the power grid;

Fig. 2 is the structural representation of control unit in the embodiment of the present utility model;

Fig. 3 is a schematic structural view of a device control module in an embodiment of the present invention;

Fig. 4 is a schematic structural view of a valve group unit in an embodiment of the present invention;

Fig. 5 is a schematic structural diagram of an IEGT phase module in an embodiment of the present invention.

Explanation of reference signs

1. Sub-harmonic reactive power generating device;

10. Control unit; 20. Valve group unit; 30. Power supply unit; 40. Cooling unit;

101. Industrial computer; 102. System control module; 103. Device control module;

1031. Phase-locked loop module; 1032. Voltage loop module; 1033. Park conversion module; 1034. Active-reactive current decoupling control module; 1035. Park inverse conversion module; 1036. SPWM modulation module.

301. UPS module; 302. Power isolation module; 303. Low-voltage power distribution module.

Detailed ways

The specific embodiment of the utility model will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the utility model, and are not intended to limit the utility model.

As shown in Figure 1, in the power system, the generator set transmits electric energy to the grid through the transformer and the transmission line. In order to reduce the transmission loss of the transmission line, the method of increasing the series compensation is often used to improve the transmission capacity of the transmission line. However, this method of increasing series compensation may also cause the problem of subsynchronous oscillation, causing the generator set to operate at an oscillation frequency lower than the synchronous frequency, which seriously affects the safety of the power system. Therefore, many devices to suppress subsynchronous oscillation are used in power plants.

The purpose of this embodiment is to suppress sub-synchronous oscillation by generating sub-harmonic current, and a sub-harmonic reactive power generating device 1 is provided, as shown in Figure 1, which is set between the generator set and the power grid, including control The unit 10 and the valve group unit 20, wherein: the control unit 10 is used to obtain the speed deviation signal of the generator set, and determine the sub-harmonic current required to suppress the subsynchronous oscillation according to the speed deviation signal, and then based on the dq transformation pair The grid voltage and the required sub-harmonic current are sequentially subjected to active-reactive decoupling and pulse width modulation, and the modulated signal is used to drive the valve group unit, so that the sub-harmonic current emitted by the valve group unit is Reactive power: the valve group unit 20 is used to generate sub-harmonic current under the drive of the control unit, and inject the generated sub-harmonic current into the grid in the form of reactive power.

As shown in Figure 2, the control unit is a control unit 10 of a cabinet structure, which may include: an industrial computer 101 for realizing interface display and operation; a system control module 102 for communicating with the industrial computer 11 for Calculating the sub-harmonic current required to suppress the sub-synchronous oscillation according to the speed deviation signal; and the device control module 103, which communicates with the industrial computer 101 and is located downstream of the system control module, and is used to adjust the grid voltage based on dq transformation Active-reactive decoupling and modulation are performed sequentially with the required sub-harmonic current, and the modulated signal is used to drive the valve group unit, so that the sub-harmonic current emitted by the valve group unit is all reactive. In addition, according to the site conditions, the control unit 10 can also be configured with a switch, which is used in conjunction with the industrial computer, so that the application range of the industrial computer is wider.

The system control module mainly completes operation logic, signal measurement, system control (power factor compensation, oscillation suppression control) and the like. It is well known in the art that the speed change of the generator set is closely related to the subsynchronous oscillation, so there are many algorithms for calculating the subharmonic current required to suppress the subsynchronous oscillation according to the speed deviation signal. Generally, the speed deviation signal is used to Perform modal filtering, extract the modal component related to the sub-harmonic current that is concerned, and then perform phase-locking, proportional amplification, phase shifting and calculation on the modal component to obtain the amplitude and phase of the required sub-harmonic current , combined with the shafting torsional vibration frequency of the generator set, the corresponding sub-harmonic current is calculated.

The device control module 103 has a dq decoupling control function, the structure of the device control module in this embodiment is preferably the structure shown in Figure 3, which includes: a phase-locked loop module 1031 for tracking and monitoring the grid voltage Phase-locked; voltage loop module 1032, used to calculate the deviation signal of the DC side voltage reference value and the DC side voltage feedback value of the valve group unit, and perform PI adjustment and phase conversion on the deviation signal, and output the active component Two Park transformation modules 1033, one of which is located downstream of the phase-locked loop 131 module, is used to perform dq transformation on the grid voltage to obtain the active component of the grid voltage and The other is used to perform dq transformation on the required sub-harmonic current to obtain the active component of the required sub-harmonic current and reactive component Active-reactive current decoupling control module 1034, which is located downstream of the Park transformation module 1033, is used to decouple all active components and reactive components obtained above, and output voltage vector The Park inverse conversion module 1035, which is located downstream of the active-reactive current decoupling control module 1034, is used to convert the voltage vector Transform to get a three-phase modulation signal and And the SPWM modulation module 1036, which is located at the downstream of the Park inverse transformation module 1035, for three-phase modulation signal and Perform SPWM modulation to obtain a corresponding PWM driving signal to drive the valve group unit.

Referring to Figure 3, the function realization of the device control module mainly includes the following links:

(1) Phase-locked loop (PLL)

Phase-locked loop is used to track A, B, C phase system voltage Its fundamental wave phase θ can be obtained, as well as the sine and cosine values of the system voltage phase.

(2) Voltage ring

Calculate DC link voltage reference value and DC side voltage feedback value The deviation signal, after the deviation signal is adjusted by PI and phase transformed, the active component is output

(3) Park transformation

The desired subharmonic current After Park transformation, we get active component and reactive components power voltage Also through the Park coordinate transformation from the abc coordinate system to the dq coordinate system, we get and

(4) Current decoupling control

Input the amount obtained after the above transformation into the active and reactive current decoupling controller, and combine the corresponding phase transformation to output the voltage vector The three-phase modulation signal is obtained through Park inverse transformation and The modulated signal outputs the PWM drive signal through the SPWM generator, so that the new sub-harmonic reactive power generator outputs the required reactive power.

The control unit of this embodiment adopts the dq control strategy, after decoupling the active component and the reactive component in the system, they respectively perform independent closed-loop control. The dq decoupling control has the advantages of good tracking performance and small steady-state error.

In addition, the control unit of this embodiment also adopts a carrier phase shifting technology, and a carrier phase shifting module is arranged downstream of the SPWM modulation module to perform carrier phase shifting on the PWM driving signal processed by the SPWM modulation module, Specifically, it includes: a control algorithm for generating PWM waves by moving multiple carriers at a certain angle on the time axis, and series connection of N-level power units requires N triangular carriers. The carrier phase-shifting technology can realize the effect of higher switching frequency at lower device switching frequency, and increase the equivalent switching frequency through the mutual cancellation of switching sub-harmonics, instead of simply shifting the harmonics to high-order, so it has the advantages of Good harmonic characteristics, while increasing the capacity of the device, effectively reduces the output harmonics and improves the signal transmission bandwidth of the entire device. In addition, the carrier phase shifting technology also has a series of advantages such as good linearity and superior control performance.

As shown in Figure 4, the valve group unit 20 in this embodiment is preferably a chain structure corresponding to a three-phase three-wire power grid, and each phase is connected in series with several IEGT phase modules. Preferably, each phase is composed of six IEGT phase modules. Module cascade composition. In Figure 4, the valve group unit is connected to the power grid through a reactor in a star connection mode, and various high-order characteristic harmonics in the sub-harmonic reactive power generation device are filtered out through the reactor. In addition, each IEGT phase module is connected in parallel with a capacitor, and the capacitor acts as a bypass protection function. In this embodiment, the sub-harmonic current is superimposed on the reactive axis to ensure that the sub-harmonics emitted by the device are all reactive without affecting the capacitor voltage of the valve group unit.

Figure 5 shows a preferred structure of the IEGT phase module, which includes: a switching device IEGT1 and a switching device IEGT2, the switching device IEGT1 is connected in parallel with a freewheeling diode D1, the switching device IEGT2 is connected in parallel with a freewheeling diode D2, and the switching device IEGT1 It is connected in series with the switching device IEGT2, and the intermediate connection end is taken out as an output end.

The IEGT phase module described in this embodiment adopts closed installation, water cooling and heat dissipation technology, and meets the relevant requirements of the IEGT power phase module for installation, heat dissipation, electromagnetic compatibility, high voltage insulation, and modular design.

In addition, the IEGT phase module also includes a buffer absorption circuit, also shown in Figure 5, the buffer absorption circuit includes two series connected inductors L1, L2, resistor R, diode D3 and capacitor C, the positive end of the diode D3 is connected to the inductor L2 The negative end of diode D3 is connected to one end of resistor R, and the other end of resistor R is connected to inductor L1; the negative end of diode D3 is also connected to one end of capacitor C, and the other end of capacitor C is connected to the negative end of the power supply.

In addition, as shown in FIG. 1 , the sub-harmonic reactive power generating device of this embodiment also includes a power supply unit 30 with a cabinet structure, and the power supply unit 30 is used to provide power for the control unit 10 and the valve group unit 20, etc. Provide corresponding working power supply, and this power supply unit comprises again: UPS module 301, is used for providing uninterrupted AC power supply; The uninterrupted AC power provided is rectified, and the rectified power is provided to the low-voltage power distribution module 303; and the low-voltage power distribution module 303 is connected to the control unit and the valve group unit for supplying The control unit and the valve group unit distribute working power.

In this embodiment, the power isolation module can use a power isolation cabinet, which can convert the 380V power into the required power and has an isolation function. The UPS module is also equipped with a battery to ensure that it can directly provide power to the valve group unit in the event of a mains power failure to avoid device damage. The low-voltage power distribution module described in this embodiment is also a cabinet structure, mainly for dual-circuit power supply, the working power supply is three-phase four-wire 380VAC/50HZ, adopts ATS automatic switching system, and the output voltage is AC380V/50HZ and AC220/50HZ. kind. The main function of the low-voltage power distribution module is to distribute AC power for the electrical equipment of the sub-harmonic generator, collect UPS feedback power, and distribute UPS power. The AC loads output by it are mainly valve group units, control units, and cooling units.

At the same time, in order to dissipate heat from the valve group unit 20, the sub-harmonic reactive power generating device of this embodiment also includes a heat dissipation unit 40, which is used to dissipate heat from the valve group unit to ensure long-term stable operation of the system. In this embodiment, the heat dissipation unit is preferably a water cooling system.

In summary, the sub-harmonic reactive power generating device of the present invention can operate in constant reactive power mode to suppress the sub-synchronous oscillation of the generating set, and has the advantages of fast response speed and good tracking performance.

The preferred embodiment of the utility model has been described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the specific details of the above-mentioned embodiment, and within the scope of the technical concept of the utility model, the technical solution of the utility model can be carried out in many ways. These simple modifications all belong to the protection scope of the present utility model.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, the utility model will not further describe various possible combinations.

In addition, any combination of various implementations of the present invention can also be made, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (10)

1. A sub-harmonic reactive power generator, characterized in that it comprises a control unit and a valve group unit, wherein: The control unit is used to obtain the speed deviation signal of the generator set, and calculate the sub-harmonic current required to suppress the sub-synchronous oscillation according to the speed deviation signal, and then sequentially calculate the grid voltage and the required sub-harmonic current based on the dq transformation Perform active-reactive power decoupling and pulse width modulation, and drive the valve group unit with the modulated signal, so that the subharmonic currents sent by the valve group unit are all reactive; The valve group unit is used to generate sub-harmonic current under the drive of the control unit, and inject the generated sub-harmonic current into the grid in the form of reactive power. 2. The sub-harmonic reactive power generating device according to claim 1, further comprising a power supply unit of a cabinet structure, which is used to provide corresponding work for the control unit and the valve group unit power supply, and the power supply unit in turn includes: UPS module for providing uninterrupted AC power; A power isolation module, which is connected to the UPS module and the low-voltage power distribution module, is used to rectify the uninterrupted AC power provided by the UPS module, and provide the rectified power to the low-voltage power distribution module; and The low-voltage power distribution module is connected to the control unit and the valve group unit, and is used for distributing working power to the control unit and the valve group unit. 3. The sub-harmonic reactive power generating device according to claim 1, wherein the control unit is a cabinet structure, comprising: Industrial computer, used to realize interface display and operation; A system control module, which communicates with the industrial computer, and is used to calculate the subharmonic current required to suppress subsynchronous oscillation according to the speed deviation signal; and The device control module, which communicates with the industrial computer and is located downstream of the system control module, is used to sequentially perform active-reactive decoupling and modulation on the grid voltage and the required sub-harmonic current based on dq transformation, and use The modulated signal drives the valve group unit, so that the sub-harmonic currents sent by the valve group unit are all reactive. 4. The sub-harmonic reactive power generating device according to claim 3, wherein the device control module comprises: Phase-locked loop module for tracking and phase-locking the grid voltage; The voltage loop module is used to calculate the deviation signal of the DC side voltage reference value and the DC side voltage feedback value of the valve group unit, and perform PI adjustment and phase conversion on the deviation signal, and output the active component Two Park transformation modules, one of which is located downstream of the phase-locked loop 131 module, is used to perform dq transformation on the grid voltage to obtain the active component of the grid voltage and The other is used to perform dq transformation on the required sub-harmonic current to obtain the active component of the required sub-harmonic current and reactive component Active-reactive current decoupling control module, which is located downstream of the Park transformation module, is used to decouple all active components and reactive components obtained above, and output voltage vector The Park inverse conversion module, which is located downstream of the active-reactive current decoupling control module, is used to convert the voltage vector Transform to get a three-phase modulation signal and as well as SPWM modulation module, which is located in the downstream of the Park inverse transformation module, for three-phase modulation signal and Perform SPWM modulation to obtain a corresponding PWM driving signal to drive the valve group unit. 5. The sub-harmonic reactive power generating device according to claim 4, wherein the device control module also includes a carrier phase-shifting module positioned downstream of the SPWM modulation module for carrier-shifting the PWM drive signal Phase processing. 6. The sub-harmonic reactive power generating device according to claim 1, characterized in that, the valve unit is a chain structure corresponding to a three-phase three-wire power grid, and each phase has several IEGT phase modules connected in series. 7. The sub-harmonic reactive power generating device according to claim 6, wherein the IEGT phase module comprises: a switching device IEGT1 and a switching device IEGT2, the switching device IEGT1 is connected in parallel with a freewheeling diode D1, and the switching device IEGT2 is connected in parallel There is a freewheeling diode D2, the switching device IEGT1 and the switching device IEGT2 are connected in series, and the intermediate connecting end is drawn out as an output end. 8. The sub-harmonic reactive power generating device according to claim 7, characterized in that, the IEGT phase module also includes a buffer absorption circuit, which includes two series-connected inductors L1, L2, resistor R, and diode D3 and capacitor C, the positive end of diode D3 is connected to inductor L2, the negative end of diode D3 is connected to one end of resistor R, and the other end of resistor R is connected to inductor L1; the negative end of diode D3 is also connected to one end of capacitor C, and the other end of capacitor C One end is connected to the negative end of the power supply. 9. The sub-harmonic reactive power generator according to any one of claims 1 to 8, further comprising: The heat dissipation unit is used for heat dissipation of the valve group unit. 10. The sub-harmonic reactive power generating device according to claim 9, characterized in that the heat dissipation unit adopts a water cooling system.