CN118137887A - Alternating-current excitation system and starting method for variable-speed pumped storage unit - Google Patents
Alternating-current excitation system and starting method for variable-speed pumped storage unit Download PDFInfo
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Abstract
The application relates to a motor control technology, and provides an alternating current excitation system and a starting method for a variable-speed pumped storage unit.
Description
Technical Field
The application belongs to the technical field of motor control, and particularly relates to an alternating current excitation system, a starting method and a computer readable storage medium for a variable-speed pumped storage unit.
Background
Because the new energy grid-connected capacity is gradually improved, higher requirements are put forward on the peak regulation and frequency modulation capacity of the power grid, and the pumped storage power station is one of means for guaranteeing the stable operation of the power system as an important mode of peak regulation and valley filling.
Pumped storage systems are divided into two main categories, fixed speed pumped storage and variable speed pumped storage, using an electro-magnetic motor and a doubly-fed induction motor (Doubly Fed Induction Generators, DFIG), respectively. The variable-speed pumped storage unit can be near the rated synchronous speed, the running efficiency of the water pump turbine is improved by adjusting the rotating speed, the abrasion is reduced, the active power can be adjusted under the electric and power generation working conditions, the frequency modulation response is quick, the precision is high, and the automatic starting can be realized.
The variable-speed pumped storage unit can be started through a speed regulator under the power generation condition, the pumping condition needs the unit to be started automatically, the current self-starting method is to short-circuit a doubly-fed induction motor stator, an alternating-current excitation system is connected with the doubly-fed induction motor rotor, when the starting motor is accelerated to the rated synchronous speed, a stator side short-circuit switch is disconnected again, a stator side main switch is closed after the stator voltage is synchronous with the power grid voltage, and the starting process is completed after the stator side short-circuit switch is integrated into the power grid. However, the current method of using this self-starting has the problem that the doubly fed induction machine of the variable speed pumped storage unit typically has a stator to rotor winding turns ratio of less than 0.5 for energy conservation during steady state operation. When the alternating-current excitation system is connected with the doubly-fed induction motor rotor, leakage inductance of the motor stator and the rotor needs to be equivalent to the rotor side, and the equivalent leakage inductance is very large. This limits the capacity of the high speed section, resulting in a longer acceleration time for self-starting of the variable speed water pump set.
Disclosure of Invention
The application aims to provide an alternating current excitation system, a starting method and a computer readable storage medium for a variable speed pumped storage unit, and aims to solve the problem that in the related art, the self-starting acceleration time of the variable speed pumped storage unit is long.
In a first aspect, an embodiment of the present application provides a starting method for a variable speed pumped-storage unit, including:
in response to a unit start command, shorting the unit rotor, connecting the ac excitation system side to the unit stator;
And controlling the side of the alternating current excitation system to carry out excitation driving on the stator of the unit, so that the unit is accelerated to the grid-connected rotating speed.
In one embodiment, the controlling the ac excitation system side to perform excitation driving on the stator of the unit to increase the speed of the unit to the grid-connected rotation speed includes:
and controlling the alternating-current excitation system to output a driving signal to a stator of the unit, wherein the driving signal is used for driving the unit to rise to the grid-connected rotating speed through a constant torque current acceleration stage, a constant power acceleration stage and a constant output voltage acceleration stage in sequence.
In one of the embodiments of the present invention,
The control alternating current excitation system machine side direction unit stator output drive signal includes:
the side of the alternating current excitation system is controlled to constantly output a target torque current to a stator of the unit so as to drive the unit to enter the constant torque current acceleration stage, wherein the target torque current is as follows: ；
When the output power of the AC excitation system side reaches the rated power of the AC excitation system network side, controlling the AC excitation system side to constantly output the rated power to the unit stator so as to drive the unit to enter the constant power acceleration stage;
When the output voltage of the AC excitation system side reaches the maximum output voltage of the AC excitation system side, controlling the AC excitation system side to constantly output to the unit stator at the maximum output voltage of the AC excitation system side so as to drive the unit to rise to the grid-connected rotating speed in the constant output voltage acceleration stage;
wherein, in the constant output voltage acceleration stage, the maximum torque current of the machine side of the alternating current excitation system to the machine set stator is ；
In the above-mentioned description of the invention,For maximum output current of AC excitation system side,/>For excitation current preset based on unit parameters,/>Is stator leakage inductance,/>Is the output angular frequency target value when the stator side of the alternating current excitation system is started,/>The maximum output voltage of the alternating current excitation system is obtained.
In one embodiment, the method further comprises:
responding to the acceleration of the unit to the grid-connected rotation speed, controlling the side of the alternating current excitation system to stop excitation driving of the unit stator, and disconnecting the short circuit of the unit rotor and the connection between the side of the alternating current excitation system and the unit stator;
The side of the alternating current excitation system is controlled to carry out excitation driving on the unit rotor to finish grid connection;
Entering into the water pumping control stage.
In one embodiment, the controlling the ac excitation system side to perform excitation driving on the unit rotor to complete grid connection includes:
responding to the complete demagnetization of the unit, controlling the side of the alternating current excitation system to be connected with the unit rotor and performing excitation driving on the unit rotor;
Adjusting excitation drive to synchronize the amplitude, frequency and phase of the stator side voltage of the unit and the voltage of a stator power grid;
And connecting a stator power grid with a stator of the unit to complete grid connection.
In one embodiment, the adjusting the excitation drive to synchronize the magnitude, frequency, phase of the unit stator side voltage with the stator grid voltage includes:
Adjusting exciting current according to the amplitude difference value of the stator side voltage of the unit and the stator power grid voltage, so that the amplitude of the stator side voltage of the unit and the amplitude of the stator power grid voltage are synchronous;
the output frequency of the AC excitation system side is regulated so that the voltage phase of the stator of the unit and the voltage phase of the stator power grid are synchronous.
In one embodiment, before shorting the unit rotor, the method further includes:
and starting an alternating current excitation system to charge the direct current bus, so that the bus voltage is increased to the rated voltage and maintained.
In one embodiment, the starting the ac excitation system charges the dc bus to increase the bus voltage to the rated voltage, including:
Pre-charging the direct current bus to a pre-charging voltage through a soft start circuit;
connecting the network side of the alternating current excitation system with an excitation power grid;
and controlling the network side of the alternating current excitation system to charge the direct current bus to rated voltage and maintain the direct current bus.
In a second aspect, an embodiment of the present application further provides an ac excitation system for a variable speed pumped storage unit, including a controller, and an ac excitation incoming line breaker, a grid-side converter, a rotor-side output breaker, a rotor short circuit breaker, a stator start-up breaker, a stator main breaker and a phase change switch, which are respectively connected to the controller, wherein the grid-side converter is connected to the side converter through a dc bus, the grid-side converter is connected to an excitation grid through the ac excitation incoming line breaker, the side converter is connected to a unit rotor through the rotor-side output breaker, the rotor short circuit breaker is used for shorting the unit rotor, the side converter is connected to a unit stator through the stator start-up breaker, the phase change switch is connected to the stator main breaker, the stator main breaker is used for connecting the unit stator, and the phase change switch is further used for connecting the stator grid, and the controller is used for executing the steps of the above-mentioned start-up method for the variable speed pumped storage unit.
In a third aspect, embodiments of the present application also provide a computer readable storage medium storing a computer program which, when executed by a controller, performs the steps of the start-up method for a variable speed pumped-hydro energy storage unit as described above.
Compared with the related art, the embodiment of the application has the beneficial effects that: the starting method for the variable-speed pumped storage unit is characterized in that a unit rotor is short-circuited when the variable-speed pumped storage unit is started, the side of an alternating current excitation system is controlled to carry out excitation driving on a unit stator so as to enable the unit to speed up, the influence of leakage inductance of the motor stator and the rotor is reduced, the starting speed of the unit is accelerated, the self-starting acceleration time of the unit is shortened, and the minimum grid-connected rotating speed can be reached.
Drawings
FIG. 1 is a schematic diagram of an AC excitation system for a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 2 is a flow chart of a method for starting a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 3 is a flow chart of a method for starting a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 4 is a timing diagram of a circuit breaker actuation command for a method of actuation of a variable speed pumped-storage unit in accordance with one embodiment of the present application;
FIG. 5 is a DC bus charge control loop diagram for a startup method of a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 6 is a waveform diagram of a rotor-side self-starting simulation execution process of an AC excitation system according to the prior art;
FIG. 7 is a waveform diagram depicting a simulated implementation of a starting method for a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 8 is a flow chart of a method for starting a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 9 is a diagram of a grid-tie control loop for a method of starting a variable speed pumped-storage unit according to an embodiment of the present application;
FIG. 10 is a pumping control loop diagram of a method for starting a variable speed pumped-storage unit according to an embodiment of the present application;
Fig. 11 is a schematic structural diagram of an ac excitation system for a variable speed pumped-storage unit according to an embodiment of the present application.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
It will be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
It is to be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are merely for convenience in describing and simplifying the description based on the orientation or positional relationship shown in the drawings, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the application.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
As shown in fig. 1, an ac excitation system for a variable-speed pumped-storage unit according to an embodiment of the present application includes a controller (not shown), and ac excitation line breakers K1, a grid-side inverter 110, a side inverter 120, a rotor-side output breaker K2, a rotor shorting breaker K3, a stator starting breaker K4, a stator main breaker K5, and a phase change switch K6, which are respectively connected to the controller, the grid-side inverter 110 and the side inverter 120 are connected through a dc bus, the grid-side inverter 110 is connected to an excitation grid through the ac excitation line breakers K1, the side inverter 120 is connected to a unit rotor through the rotor-side output breakers K2, the rotor shorting breaker K3 is used for shorting the unit rotor, the side inverter 120 is connected to the unit stator through the stator starting breakers K4, the phase change switch K6 is connected to a stator main breaker K5, the stator main breaker K5 is used for connecting the unit stator, and the phase change switch K6 is also used for connecting the stator grid. The phase change switch K6 does not act in the starting process, and the phase change switch K6 is used for switching between a water pumping working condition and a power generating working condition. In this embodiment, the ac excitation system of the variable speed pumped storage unit (abbreviated as unit) is used for controlling the doubly-fed induction motor.
In some embodiments, a dc Chopper circuit 130 is connected to a dc bus of the ac excitation system side (i.e., the side converter 120), and the dc Chopper circuit 130 is used to discharge energy when the power grid is high or low. In alternative embodiments, the dc chopper circuit 130 may also be replaced with an ac Crowbar (Crowbar) circuit to consume energy when the grid is high or low.
In some embodiments, a stator side of the doubly-fed induction machine (hereinafter referred to as a unit) is provided with a stator voltage sampling device TV1 and a stator current sampling device TA1, a grid side of the ac excitation system (i.e., a grid side converter 110) is provided with an excitation grid voltage sampling device TV2 and an excitation grid current sampling device TA2, the stator grid side is provided with a stator grid voltage sampling device TV3, the ac excitation system side is provided with an output current sampling device TA3, and a dc bus voltage sampling device TV4 is provided on a dc bus.
As shown in fig. 2, an embodiment of the present application further provides a starting method for a variable speed pumped-storage unit based on the ac excitation system of any one of the above embodiments, including:
Step S110, in response to the unit start command, shorting the unit rotor, connecting the ac excitation system side to the unit stator.
The circuit breakers are in an open state, the alternating current excitation system receives a unit starting command issued by the controller, for example, the alternating current excitation system is used for pumping working conditions, and the voltage frequency of the excitation power grid collected by the excitation power grid voltage sampling device TV2 meets the starting condition.
And when the unit rotor is short-circuited, the unit rotor forms a loop when the unit stator is excited and driven. The machine side of the alternating current excitation system is connected to the machine set stator so as to carry out excitation driving on the machine set stator.
And step S120, controlling the side of the alternating current excitation system to carry out excitation driving on the stator of the unit, so that the unit is accelerated to the grid-connected rotating speed.
Specifically, the controller sends waves to the machine side converter 120, so that the machine side converter 120 converts power of a power grid provided by an excitation power grid to an alternating current excitation system into excitation driving current, and the closed-loop vector control drives a unit stator, so that a unit rotor rises to a grid-connected rotating speed, and quick starting of the unit is completed. The grid-connected rotating speed refers to the rotating speed of a unit rotor of an alternating-current excitation system capable of realizing grid connection of a variable-speed pumped storage unit.
According to the technical scheme provided by the embodiment of the application, the machine set rotor is short-circuited during starting, and the machine set stator is controlled to be excited and driven by the side of the alternating-current excitation system to increase the speed of the machine set, so that the influence of leakage inductance of the motor stator and the rotor is reduced, the starting speed of the machine set is accelerated, the self-starting acceleration time of the machine set is shortened, and the lowest grid-connected rotating speed can be achieved.
In one embodiment, the starting method in step S110 further includes, before shorting the unit rotor: and starting an alternating current excitation system to charge the direct current bus, so that the bus voltage is increased to the rated voltage and maintained. So that the side converter 120 can obtain stable driving power from the dc bus.
As shown in fig. 3, in one embodiment, starting the ac excitation system to charge the dc bus to raise the bus voltage to the rated voltage and maintain it, includes:
step S210, the direct current bus is precharged to a precharge voltage through a soft start circuit.
The network side soft start switch of the alternating current excitation system is closed, and the excitation power grid charges the direct current bus through the soft start resistor and the network side anti-parallel diode. When the direct current voltage is greater than the pre-charge voltage (for example, any value between 0.4pu and 0.7 pu) by 0.6pu, and the soft start switch is turned off after a certain time. It will be appreciated that the pre-charge voltage is related to the voltage amplitude of the excitation grid.
And step S220, connecting the network side of the alternating current excitation system with an excitation power grid. I.e. to control the closing of the ac excitation line breaker K1, see fig. 4.
And step S230, controlling the network side of the alternating current excitation system to charge the direct current bus to the rated voltage and maintain the direct current bus.
Illustratively, the controller modulates the wave generation on the network side of the alternating-current excitation system, and continues to charge the direct-current bus until the rated voltage is reached and the bus voltage is maintained constant.
In one embodiment, the network side control of the ac excitation system for charging the dc bus is shown in fig. 5, and may be divided into links such as a dc bus loop, a phase-locked loop, an active current loop, a reactive current loop, and a modulated wave generation.
The bus voltage given value and the bus voltage feedback value are sent to the input end of the direct current bus ring, and the bus ring controller (such as a PI controller) calculates the bus voltage given value and the bus voltage feedback value according to the difference pole of the bus voltage given value and the bus voltage feedback value to obtain an active current reference value.
The reactive current reference value is from a user setting. The exciting network current sample sampled by the exciting network current sampling device TA2 is subjected to vector directional decomposition (for example, clarke-Park conversion) to obtain an active current feedback value and a reactive current feedback value, and the phase-locked loop angle is obtained by the vector directional angle. The phase-locked loop (Phase Locked Loop, PLL) sets the phase-locked loop angle from the grid-side voltage sampled by the excitation grid voltage sampling device TV 2.
The difference between the active current reference value and the active current feedback value is sent to the active current loop input end, and the difference between the reactive current reference value and the reactive current feedback value is sent to the reactive current loop input end. Output of active current loop controller overlaps d-axis voltage feedforward quantity of AC excitation system net side; Output of reactive current loop controller is overlapped with network side q-axis voltage/>, of alternating current excitation systemThe power device driving pulse signal is output by the modulation wave generation link as the power device driving pulse signal of the AC excitation system network side, the DC bus is charged until the bus voltage reaches a steady state, and then the third phase of the unit starting acceleration phase is switched.
In one embodiment, step S120 includes: and controlling the alternating-current excitation system to output a driving signal to the stator of the unit, wherein the driving signal is used for driving the unit to rise to the grid-connected rotating speed through a constant torque current acceleration stage, a constant power acceleration stage and a constant output voltage acceleration stage in sequence.
In this process, the rotor-side output breaker K2 and the stator main breaker K5 are controlled to maintain an open state, see fig. 4.
In one embodiment, controlling the ac excitation system machine to output a drive signal to the unit stator includes:
the side of the alternating current excitation system is controlled to constantly output target torque current to a stator of the unit so as to drive the unit to enter a constant torque current acceleration stage, wherein the target torque current is as follows: ；
When the output power of the AC excitation system side reaches the rated power of the AC excitation system network side, controlling the AC excitation system side to constantly output the rated power to a stator of the unit so as to drive the unit to enter a constant power acceleration stage;
When the output voltage of the AC excitation system side reaches the maximum output voltage of the AC excitation system side, controlling the AC excitation system side to constantly output the maximum output voltage of the AC excitation system side to a stator of the unit so as to drive the unit to rise to a rated rotation speed in an acceleration stage of the constant output voltage;
Wherein, in the constant output voltage acceleration stage, the maximum torque current of the alternating current excitation system side to the machine set stator is 。
In the above-mentioned method, the step of,For maximum output current of AC excitation system side,/>Given by exciting current corresponding to unit parameters,/>Is stator leakage inductance,/>Is the output angular frequency target value when the alternating current excitation system stator side starts,The maximum output voltage of the alternating current excitation system is obtained.
In the process that the machine side of the alternating current excitation system drives the machine set stator to increase the machine set rotating speed, the machine side output voltage and active power of the alternating current excitation system are gradually increased, and when the machine side output power of the alternating current excitation system reaches the rated power of the machine side of the alternating current excitation system, the machine side drive machine set stator automatically enters a power limiting acceleration stage.
In a constant power acceleration stage, namely in a limited power acceleration stage, the power output by the side of the alternating current excitation system to the stator of the unit is constant as the rated power of the alternating current excitation system. The rotating speed of the random group rises, the side output voltage of the alternating-current excitation system and the leakage inductance voltage drop of the motor are gradually increased, and the voltage level of the stator power grid of the variable-speed pumped storage system is far greater than the side output voltage capacity of the alternating-current excitation system, so that the insulation problem of a machine set is not worried. When the output voltage of the AC excitation system side reaches the maximum value, the phase of reducing the torque current and accelerating is automatically entered.
In the constant output voltage acceleration stage, namely the torque-reducing current acceleration stage, the output voltage of the machine set stator of the alternating-current excitation system side is constant to the maximum output voltage of the alternating-current excitation system side, and the maximum torque current is。
Wherein, the rated voltage of the stator of the unitOpen-circuit voltage of unit rotor/>Actual voltage of unit stator/>Grid frequency is/>The lowest grid-connected rotation speed is/>The highest grid-connected rotation speed is/>。
For example, a true waveform diagram of a rotor side self-starting simulation execution process of an ac excitation system in the prior art is shown in fig. 6, the rotation speed is basically stable after the rotor side self-starting simulation execution process is started for half an hour (between the zone bits X1 and X2 in fig. 6), the traction torque and the load torque of the unit are approximately equal, at this time, the rotation speed is about 349RPM (revolutions per minute), the minimum grid-connected rotation speed requirement of the system is not met, and self-starting cannot be realized.
The simulation waveform diagram of the executing process of the starting method for the unit provided by the embodiment of the application is shown in fig. 7, and after the unit is started for 11.3 minutes (between the zone bits X1 and X2 in fig. 7), the traction torque and the load torque of the unit are approximately equal, and the rotating speed is about 550RPM, is greater than the lowest grid-connected rotating speed and is less than the maximum grid-connected rotating speed, so that the minimum grid-connected rotating speed requirement of the system is met.
Therefore, compared with the driving of the alternating current excitation system from the stator side driving unit, the alternating current excitation system is started from the rotor side, the starting speed is higher, and the lowest grid-connected rotating speed can be achieved.
As shown in fig. 8, in one embodiment, the starting method further includes:
And step S310, in response to the unit speed up to the grid-connected rotating speed, the short circuit of the unit rotor and the connection between the side of the alternating current excitation system and the unit stator are disconnected.
Namely, the rotor shorting breaker K3 and the stator starting breaker K4 are turned off. It will be appreciated that the ac excitation system side should be controlled to stop excitation driving the stator of the unit, i.e. to stop outputting the driving signal, before the rotor shorting breaker K3 is turned off and the stator starting breaker K4.
And step S320, controlling the side of the alternating current excitation system to carry out excitation driving on the unit rotor to finish grid connection.
Specifically, the voltage on the stator side of the unit is driven to synchronize with the amplitude, frequency and phase of the voltage of the stator power grid, and after synchronization is completed, the stator main circuit breaker K5 (see fig. 5) is closed, and the grid connection process is finished.
Step S330, entering a pumping control stage.
And the normal vector control of the unit is performed by entering an alternating current excitation system. The normal vector control is used in the pumping control stage, decoupling is realized by active power and reactive power, a user can freely set the active power set value and the reactive power set value, and the active power pumping energy storage of the power grid can be absorbed, and the reactive power can be sent to the power grid.
In one embodiment, step S320 includes:
and in response to the complete demagnetization of the unit, controlling the side of the alternating current excitation system to be connected with the unit rotor and carrying out excitation driving on the unit rotor. Specifically, the exciting current is controlled to be constant by open loop to carry out exciting driving.
And adjusting excitation drive to synchronize the amplitude, frequency and phase of the stator side voltage of the unit with the voltage of a stator power grid. So as to reduce the impact of the machine set to the power grid or the impact of the power grid to the machine set.
And connecting a stator power grid with a stator of the unit to complete grid connection. I.e. closing the stator main breaker K5.
In one embodiment, adjusting the excitation drive to synchronize the magnitude, frequency, phase of the unit stator side voltage with the stator grid voltage includes:
Adjusting exciting current according to the amplitude difference value of the stator side voltage of the unit and the stator power grid voltage, so that the amplitude of the stator side voltage of the unit and the amplitude of the stator power grid voltage are synchronous;
the output frequency of the AC excitation system side is regulated so that the voltage phase of the stator of the unit and the voltage phase of the stator power grid are synchronous.
Specifically, the excitation drive is regulated to enable the amplitude, frequency and phase synchronization of the stator side voltage of the unit and the stator power grid voltage to be divided into 4 states, wherein the 1 st state is a constant excitation current state, and the excitation current of the side of the open-loop control alternating current excitation system is constant; the 2 nd state is an amplitude synchronization state, and excitation current is regulated in a closed loop according to the difference between the voltage value of a stator voltage (of a machine set) and the voltage of a stator power grid, so that the voltage value of the stator voltage and the module value (including the amplitude) of the voltage of the stator power grid are synchronized; the 3 rd state is a phase angle synchronous state, and the side output frequency of the alternating current excitation system is finely adjusted so that the phases of the stator voltage of the unit and the voltage of the stator power grid are synchronous; and the 4 th state is a grid-connected state, and the stator main breaker K5 is closed to finish grid connection.
For the grid-connected stage of step S320, the ac excitation system side starting control block diagram is shown in fig. 9, and includes links such as a torque current loop, an excitation current loop, a stator voltage module value loop, a stator voltage phase angle loop, and modulation ripple. The torque current reference value is constant at 0, and the exciting current reference value is determined by the stator voltage module value loop output.
The stator voltage sampled by the stator voltage sampling device TV1 is calculated by a phase-locked loop and a module value to obtain a stator voltage module value and a stator voltage phase angle, and the stator power grid voltage sampled by the stator power grid voltage sampling device TV3 is calculated by the phase-locked loop and the module value to obtain a stator power grid voltage module value and a stator power grid voltage phase angle.
The difference value between the stator power grid voltage value and the stator voltage value is calculated and output to an excitation current reference value through a stator voltage value loop controller.
And adding a compensation angle to the difference between the voltage phase angle of the stator power grid and the voltage phase angle of the stator, calculating and outputting stator frequency through a stator voltage phase angle loop controller, and obtaining a stator frequency integral value through an integrator. The difference between the stator frequency and the rotor angle is the rotor flux angle. The output current sampled by the output current sampling device TA3 is vector-directionally decomposed (for example, clarke-Park conversion) into a torque current feedback value and an exciting current feedback value.
The difference between the torque current reference value and the torque current feedback value is sent to the torque current loop input end, and the difference between the exciting current reference value and the exciting current feedback value is sent to the exciting current loop input end.
Output of torque current loop controller superimposes q-axis voltage feedforward quantity of AC excitation systemOutput of excitation current loop controller is overlapped with d-axis voltage feedforward quantity/>, of alternating current excitation systemThe modulated wave generating link is input together with the angle of the rotor flux linkage, and the modulated wave generating link outputs power device driving pulses of the side of the alternating current excitation system. The stator voltage and the stator grid voltage can be synchronized through the control, and preparation is made for grid connection. Wherein the network side of the alternating current excitation system uses the q-axis voltage feedforward quantity/>D-axis voltage feedforward amount/>And the adaptability of the power grid is enhanced, and the d and q axes are decoupled.
In the pumping control stage, a vector control block diagram of the side of the alternating current excitation system is shown in fig. 10, and the vector control block diagram comprises links such as a torque current loop, an excitation current loop, a speed loop, a reactive power loop, a modulation wave generation and the like.
The difference between the set speed value and the speed feedback value of the unit is calculated by the speed loop controller to output a torque current reference value. The difference between the reactive power given value and the reactive power calculated value is calculated and output an exciting current reference value through the reactive power loop controller.
The stator voltage and stator current sampled by the stator voltage sampling device TV1 and the stator current of the stator current sampling device TA1 output reactive power through reactive power calculation. The stator voltage outputs a stator voltage vector angle through the phase-locked loop. The stator voltage vector angle and the integral of the rotational speed feedback value by the integrator are the rotor magnetic chain angle. The output current of the output current sampling device is directionally decomposed into a torque current feedback value and an exciting current feedback value through vectors.
The difference between the torque current reference value and the torque current feedback value is sent to the torque current loop input end, and the difference between the exciting current reference value and the exciting current feedback value is sent to the exciting current loop input end.
Output of torque current loop controller superimposes q-axis voltage feedforward quantity of AC excitation systemOutput of excitation current loop controller is overlapped with d-axis voltage feedforward quantity/>, of alternating current excitation systemThe modulated wave generating link is input together with the angle of the rotor flux linkage, and the modulated wave generating link outputs power device driving pulses of the side of the alternating current excitation system. The control strategy is responsible for the operation control after the grid connection of the side of the alternating current excitation system is finished.
Referring to fig. 1 and 11, in a second aspect, an embodiment of the present application further provides an ac excitation system for a variable-speed pumped-storage unit, including a controller 111, and an ac excitation line breaker K1, a grid-side converter 110, a machine-side converter 120, a rotor-side output breaker K2, a rotor shorting breaker K3, a stator starting breaker K4, a stator main breaker K5, and a phase change switch K6, which are respectively connected to the controller, the grid-side converter 110 is connected to the machine-side converter 120 through a dc bus, the grid-side converter 110 is connected to an excitation grid through the ac excitation line breaker K1, the machine-side converter 120 is connected to a unit rotor through the rotor-side output breaker K2, the rotor shorting breaker K3 is used for shorting the unit rotor, the machine-side converter 120 is connected to a unit stator through the stator starting breaker K4, the phase change switch K6 is connected to the stator main breaker K5, the stator main breaker K5 is used for connecting the unit stator, and the phase change switch K6 is also used for connecting to the stator grid. The controller 111 is configured to control the steps of performing the start-up method for the variable speed pumped-storage unit described above. It will be appreciated that the ac excitation system 11 also includes a memory 112 and a computer program 1121 stored in the memory 112 and operable on the controller 111.
It will be appreciated by those skilled in the art that fig. 11 is merely an example of an ac excitation system 11 and is not meant to be limiting of the ac excitation system 11, and may include more or fewer components than shown, or may combine certain components, or may include different components, such as input-output devices, network access devices, etc.
The controller 111 may be a central processing unit (Central Processing Unit, CPU), the controller 111 may also be other general purpose controllers, digital signal controllers (DIGITAL SIGNAL Processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), off-the-shelf Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. The general purpose controller may be a microcontroller or may be any conventional controller.
The memory 112 may be an internal storage unit of the ac excitation system 11 in some embodiments, such as a hard disk or a memory of the ac excitation system 11. The memory 112 may also be an external storage device of the ac excitation system 11 in other embodiments, such as a plug-in hard disk, a smart memory card (SMART MEDIA CARD, SMC), a Secure Digital (SD) card, a flash memory card (FLASH CARD) or the like, which are provided on the ac excitation system 11. Further, the memory 112 may also include both an internal memory unit and an external memory device of the ac excitation system 11. The memory 112 is used to store an operating system, application programs, boot Loader (Boot Loader), data, and other programs, etc. The memory 112 may also be used to temporarily store data that has been output or is to be output.
The embodiment of the present application also provides a computer-readable storage medium storing a computer program 1121, which when executed by the controller 111, can implement the steps in the above-described respective method embodiments.
Embodiments of the present application provide a computer program product which, when run on a computer, causes the computer to perform the steps of the various method embodiments described above.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the present application may implement all or part of the flow of the above-described method embodiments, and may be implemented by instructing the relevant hardware by the computer program 1121, where the computer program 1121 may be stored in a computer-readable storage medium, and where the computer program 1121, when executed by the controller 111, may implement the steps of the above-described method embodiments. The computer program 1121 includes computer program 1121 code, where the computer program 1121 code may be in the form of source code, object code, executable files, some intermediate form, or the like. The computer readable medium may include at least: any entity or device capable of carrying the computer program 1121 code to a photographing apparatus/terminal device, a recording medium, a computer Memory 112, a ROM (Read-Only Memory 112), a RAM (Random Access Memory, random access Memory 112), a CD-ROM (Compact Disc Read-Only Memory), a magnetic tape, a floppy disk, an optical data storage device, and so forth. The computer readable storage medium mentioned in the present application may be a non-volatile storage medium, in other words, a non-transitory storage medium.
It should be understood that all or part of the steps to implement the above-described embodiments may be implemented by software, hardware, firmware, or any combination thereof. When implemented in software, it may be implemented in whole or in part in the form of a computer program 1121 product. The computer program 1121 product includes one or more computer instructions. The computer instructions may be stored in the computer-readable storage medium described above.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus/electronic device and method may be implemented in other manners. For example, the apparatus/electronic device embodiments described above are merely illustrative, e.g., the division of modules or units is merely a logical functional division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection via interfaces, devices or units, which may be in electrical, mechanical or other forms.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
The above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application, and are intended to be included in the scope of the present application.
Claims (10)
1. A method of starting a variable speed pumped-storage unit comprising:
in response to a unit start command, shorting the unit rotor, connecting the ac excitation system side to the unit stator;
And controlling the side of the alternating current excitation system to carry out excitation driving on the stator of the unit, so that the unit is accelerated to the grid-connected rotating speed.
2. The starting method according to claim 1, wherein the controlling the ac excitation system side to excitation-drive the stator of the unit to increase the unit speed to the grid-connected rotational speed comprises:
and controlling the alternating-current excitation system to output a driving signal to a stator of the unit, wherein the driving signal is used for driving the unit to rise to the grid-connected rotating speed through a constant torque current acceleration stage, a constant power acceleration stage and a constant output voltage acceleration stage in sequence.
3. The method of starting up of claim 2, wherein controlling the ac excitation system machine side machine set stator output drive signals comprises:
the side of the alternating current excitation system is controlled to constantly output a target torque current to a stator of the unit so as to drive the unit to enter the constant torque current acceleration stage, wherein the target torque current is as follows: ；
When the output power of the AC excitation system side reaches the rated power of the AC excitation system network side, controlling the AC excitation system side to constantly output the rated power to the unit stator so as to drive the unit to enter the constant power acceleration stage;
When the output voltage of the AC excitation system side reaches the maximum output voltage of the AC excitation system side, controlling the AC excitation system side to constantly output to the unit stator at the maximum output voltage of the AC excitation system side so as to drive the unit to rise to the grid-connected rotating speed in the constant output voltage acceleration stage;
wherein, in the constant output voltage acceleration stage, the maximum torque current of the machine side of the alternating current excitation system to the machine set stator is ；
In the above-mentioned description of the invention,For maximum output current of AC excitation system side,/>For excitation current preset based on unit parameters,/>Is stator leakage inductance,/>Is the output angular frequency target value when the stator side of the alternating current excitation system is started,/>The maximum output voltage of the alternating current excitation system is obtained.
4. A start-up method as claimed in any one of claims 1 to 3, further comprising:
Responding to the acceleration of the unit to the grid-connected rotating speed, and disconnecting the short circuit of the unit rotor and the connection between the side of the alternating current excitation system and the unit stator;
The side of the alternating current excitation system is controlled to carry out excitation driving on the unit rotor to finish grid connection;
Entering into the water pumping control stage.
5. The starting method of claim 4, wherein the controlling the ac excitation system side to perform excitation driving on the unit rotor to complete grid connection comprises:
responding to the complete demagnetization of the unit, controlling the side of the alternating current excitation system to be connected with the unit rotor and performing excitation driving on the unit rotor;
Adjusting excitation drive to synchronize the amplitude, frequency and phase of the stator side voltage of the unit and the voltage of a stator power grid;
And connecting a stator power grid with a stator of the unit to complete grid connection.
6. The method of starting up of claim 5, wherein said adjusting the excitation drive to synchronize the magnitude, frequency, phase of the unit stator side voltage with the stator grid voltage includes:
Adjusting exciting current according to the amplitude difference value of the stator side voltage of the unit and the stator power grid voltage, so that the amplitude of the stator side voltage of the unit and the amplitude of the stator power grid voltage are synchronous;
the output frequency of the AC excitation system side is regulated so that the voltage phase of the stator of the unit and the voltage phase of the stator power grid are synchronous.
7. A starting method according to any one of claims 1 to 3, wherein before shorting the unit rotor, further comprises:
and starting an alternating current excitation system to charge the direct current bus, so that the bus voltage is increased to the rated voltage and maintained.
8. The method of starting up according to claim 7, wherein said starting up the ac excitation system to charge the dc bus to raise the bus voltage to the rated voltage includes:
Pre-charging the direct current bus to a pre-charging voltage through a soft start circuit;
connecting the network side of the alternating current excitation system with an excitation power grid;
and controlling the network side of the alternating current excitation system to charge the direct current bus to rated voltage and maintain the direct current bus.
9. An ac excitation system for a variable speed pumped storage unit, comprising a controller, and an ac excitation incoming line breaker, a grid side converter, a rotor side output breaker, a rotor shorting breaker, a stator starting breaker, a stator main breaker and a phase change switch respectively connected to the controller, the grid side converter being connected to the side converter by means of a dc bus, the grid side converter being connected to an excitation grid by means of the ac excitation incoming line breaker, the side converter being connected to a unit rotor by means of the rotor side output breaker, the rotor shorting breaker being used for shorting the unit rotor, the side converter being connected to a unit stator by means of the stator starting breaker, the phase change switch being connected to the stator main breaker being used for connecting the unit stator, the phase change switch also being used for connecting the stator grid, the controller performing the steps of the starting method for a variable speed pumped storage unit according to any one of claims 1 to 8.
10. A computer readable storage medium, characterized in that it stores a computer program which, when executed by a controller, implements the steps of the starting method for a variable speed pumped-storage unit according to any one of claims 1 to 8.
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