CN115912435B - Wind power virtual inertia optimization control method and device based on energy storage and storage medium - Google Patents
Wind power virtual inertia optimization control method and device based on energy storage and storage medium Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The application discloses a wind power virtual inertia optimization control method and device based on energy storage and a storage medium, and belongs to the technical field of fan grid connection. An energy storage device is connected in parallel on a direct current bus capacitor between a machine side converter and a net side converter of the fan, and the energy storage device comprises at least 2 groups of battery packs which are different in economic cost and can work independently. The optimization control method comprises the steps of firstly, obtaining the real-time frequency of a power grid system, and the preset starting trigger frequency of an energy storage device, a system frequency reference value under disturbance, a lower limit value of the stable frequency of the power grid system and the running cut-off frequency of the power grid; and then judging the running state of the power grid according to the acquired data, and controlling the power output of one or more battery packs in the energy storage device according to the judging result so as to adapt to different inertia supporting requirements. The application of the application can enable the power grid system to effectively cope with disturbance conditions of different sizes, promote the inertia supporting capacity of the wind storage system and ensure the stability and the safety of the wind storage system.
Description
Technical Field
The application relates to the technical field of fan grid connection, in particular to a wind power virtual inertia optimization control method and device based on energy storage and a storage medium.
Background
Along with the increasing demand of clean new energy use in the social development, the scale of wind power construction and use is rapidly increased. With the grid-connected power generation of more wind power equipment, the permeability of new energy power generation such as wind power in a power system is gradually increased, and the occupation proportion of traditional thermal power is continuously reduced. Because wind power equipment is generally directly connected into a power grid through a power electronic converter, moment of inertia cannot exist to support the inertia of the power grid like a synchronous motor in traditional thermal power, and the power grid can be subjected to inertia loss risk, which seriously threatens the safe operation of the power grid.
At present, the problem of energy sources for wind power inertia support can be solved by modifying the structure of a fan of a wind power plant and equipment thereof and additionally installing an energy storage device in the wind power plant. The essence of wind power inertia support is that the VSG technology is applied, when the wind power inertia support faces to grid disturbance, the wind power inertia support simulates an inertia response link of a traditional synchronous motor, and power compensation is provided for a grid to maintain the grid frequency stability by outputting energy stored by an energy storage device, so that the mode is supported by related researches.
However, the application of the energy storage technology on wind power inertia support is still in the development stage at present, and various energy storage batteries on the market have problems, such as relatively low service life of the energy storage battery, safety problem of use of the energy storage battery, relatively high use cost of the energy storage battery and the like, so that certain restriction is formed on the application of energy storage on wind power inertia support.
Disclosure of Invention
The application aims to provide an energy storage-based wind power virtual inertia optimization control method, an energy storage-based wind power virtual inertia optimization control device and a storage medium. The technical scheme adopted by the application is as follows.
On the one hand, the application provides a wind power virtual inertia optimization control method based on energy storage, a fan is integrated into a power grid system after passing through a machine side converter and a network side converter, an energy storage device is connected in parallel on a direct current bus capacitor between the machine side converter and the network side converter, and the energy storage device comprises at least 2 groups of battery packs which have different economic costs and can work independently;
the wind power virtual inertia optimization control method comprises the following steps:
acquiring real-time frequency f of power grid system G And a preset energy storage deviceStart trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN ；
Judging whether f is satisfied according to the acquired data G ≥f on If yes, the battery pack of the energy storage device is not started;
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Controlling all battery packs in the energy storage device to start to discharge to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min And finishing inertia support, and controlling the battery pack in the energy storage device to stop discharging.
In the above technical solution, the energy storage device starts the trigger frequency f on For the frequency of the power grid system to be reduced to a critical frequency value which is about to need inertia compensation support, if the frequency of the power grid system meets f G ≥f on And the power output of the energy storage device is not required to be triggered without virtual inertia support, and the battery pack of the energy storage device is not started.
System frequency reference f under disturbance s The method is used for distinguishing the disturbance magnitude of the power grid system, and when the real-time frequency is smaller than the system frequency reference value under the disturbance, the disturbance is represented as the disturbance with a large degree. Under the disturbance conditions of different sizes, the technical scheme of the application adopts different battery pack starting control schemes so as to realize the power output mode of the energy storage battery which accords with the actual power grid disturbance size, and simultaneously can reduce the economic cost of the energy storage device.
Electric network systemLower limit f of system stable frequency G_min The lowest frequency value for the grid system operating in a relatively stable state is below which the grid is unstable. The system frequency drops to the grid operation cut-off frequency f G_MIN The power grid operation impending danger is characterized by the need of stopping operation.
Energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min Grid operation cut-off frequency f G_MIN All can be preset according to the experience value of the actual power grid system scene.
In the application, the battery packs which have different economic cost and can work independently are battery packs which adopt different materials, and comprise a lead-acid storage battery pack and a lithium iron phosphate battery pack. The economic cost of the lead-acid storage battery pack is far lower than that of the lithium iron phosphate storage battery pack, and the low-cost lead-acid storage battery pack is preferentially started when the discharge control of the energy storage device is carried out.
Optionally, the controlling the battery pack in the energy storage device to be started in order of low economic cost includes:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
Optionally, the method of the present application further comprises: and executing VSG control on the grid-side converter based on the electromechanical transient model of the synchronous generator, so that the grid-side converter can simulate inertia and damping characteristics of the synchronous generator, and control active power output by grid connection so as to provide inertia support and power compensation for a power grid system.
The VSG control part mainly comprises a power frequency controller, an excitation controller, a voltage-current double loop and a PWM generator, and can be operated in an island mode or a grid-connected mode, and the specific implementation of related control can refer to the existing off-grid and grid-connected VSG control technology.
Optionally, the energy storage device starts the trigger frequency f on Lower limit value f of stable frequency of power grid system G_min Is equal in value.
Optionally, the energy storage device further comprises a current converter and a controller, and the battery pack is connected to a direct current bus between the machine side current converter and the grid side current converter through the current converter;
the wind power virtual inertia optimization control method is executed by the controller, and the battery pack in the energy storage device is controlled to discharge by controlling the converter.
In addition, the wind power virtual inertia optimization control method can be realized by a wind power plant station end, and the station end executes control logic to output control instructions to a controller of the energy storage device to control the discharge of different battery packs according to the control instructions.
In a second aspect, the application provides an energy-storage-based wind power virtual inertia optimization control device, a fan is integrated into a power grid system after passing through a machine side converter and a grid side converter, an energy storage device is connected in parallel to a direct current bus capacitor between the machine side converter and the grid side converter, and the energy storage device comprises at least 2 groups of battery packs which are different in economic cost and can work independently;
the wind power virtual inertia optimization control device comprises:
a parameter acquisition module configured to acquire a real-time frequency f of the power grid system G And a preset energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN ；
The logic control module is configured to judge the running state of the power grid according to the acquired data, and control the battery pack in the energy storage device according to the judging result, and comprises the following steps:
judging whether or not f is satisfied G ≥f on If yes, the battery pack of the energy storage device is not started;
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Controlling all battery packs in the energy storage device to start to discharge to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min And finishing inertia support, and controlling the battery pack in the energy storage device to stop discharging.
Optionally, the logic control module controls the battery packs in the energy storage device to be started in order of low economic cost, including:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
Optionally, the wind power virtual inertia optimization control device further includes a VSG control module configured to: and executing VSG control on the grid-side converter based on the electromechanical transient model of the synchronous generator, so that the grid-side converter can simulate inertia and damping characteristics of the synchronous generator, and control active power output by grid connection so as to provide inertia support and power compensation for a power grid system.
In a third aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor, implements the wind power virtual inertia optimization control method according to the first aspect.
Advantageous effects
According to the wind power virtual inertia optimization control method, power output control of different modes is carried out on different types of battery packs in the energy storage device according to the state interval where the frequency of the real-time power grid system is located, so that optimal control of 'echelon output' of the energy storage capacity of the battery packs in the energy storage device is realized, inertia support of the system is realized, and power loss of a power grid is compensated. And the power grid disturbance of different sizes can be effectively coped with, meanwhile, the use stability and the safety of the battery are ensured, the installation and use scale of a single high-cost battery can be reduced, and the economic burden of the energy storage device in the aspects of installation and maintenance is reduced. The method can be suitable for various wind power grid-connected scenes, such as offshore wind power and the like.
Drawings
FIG. 1 is a topology diagram of a multi-energy-storage wind power virtual inertia control system according to an embodiment of the present application;
FIG. 2 is a schematic flow chart of a method for controlling virtual inertia of multi-energy-storage wind power according to an embodiment of the application;
FIG. 3 is a schematic diagram illustrating logic control of a method for controlling virtual inertia of multi-energy-storage wind power according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a frequency trace plan interval including a threshold;
FIG. 5 is a schematic diagram illustrating verification of expected effects of waveform changes of power system frequencies using the multi-energy storage wind power virtual inertia control method of the present application in one embodiment;
fig. 6 is a schematic diagram illustrating verification of an expected effect of waveform change of active power of a power system using the multi-energy-storage wind power virtual inertia control method according to an embodiment of the present application.
Detailed Description
The technical conception of the application is as follows: on one hand, the power output of the energy storage battery is optimized to cope with frequency disturbance of different sizes, required inertia support is provided for a power grid, the safety and stability of energy storage use are improved, the preparation cost of energy storage is reduced, and on the other hand, the inertia response link of a traditional synchronous motor is simulated when the grid-connected inverter is controlled, and effective power compensation is provided for the power grid.
Further description is provided below in connection with the drawings and the specific embodiments.
Example 1
The embodiment introduces a wind power virtual inertia optimization control method based on energy storage.
Referring to fig. 1, the wind turbine in this embodiment is a permanent magnet direct-drive wind turbine, and the application scenario may be an offshore wind power grid-connected scenario. The permanent magnet direct-drive fan PMSG generally works in a maximum power state, and can normally grid-connected to generate electricity to directly output active power after passing through a three-phase rectifying circuit and a three-phase inverter circuit. The PMSG can be connected with the BESS part in parallel after passing through the rectifying circuit to be used as a wind storage combined power output system, and the wind storage system can be used as a whole for grid-connected power generation through a grid-connected inverter. Because the energy storage battery works in a direct current mode, when the energy storage device is added to reform the fan, the battery energy storage device can be connected in parallel on a direct current bus of the system after a three-phase rectifying circuit of the fan, and can be used as an energy storage source of inertia support during wind power grid connection.
In the wind power grid-connected system architecture applicable to the method, the permanent magnet direct-driven fan PMSG is filtered by the machine side converter and the grid side converter LC and then is combined into a power grid system, and an energy storage device is connected in parallel to a direct-current bus capacitor between the machine side converter and the grid side converter, wherein the energy storage device comprises at least 2 groups of battery packs which are different in economic cost and can work independently.
The battery packs with different economic cost are battery packs with different materials, such as lead-acid battery pack and lithium iron phosphate battery pack respectively, each battery pack can be provided with one or more battery packs, as shown in figure 1, the two battery packs can respectively output active power P b1 And P b2 After the output voltage of the energy storage battery is increased to the voltage value required by grid connection through the respective DC-DC boost circuits, the output voltage is controlled by the controller executing the method of the embodimentAnd a direct current bus is input in a parallel mode.
The wind power virtual inertia optimization control method of the embodiment comprises the following steps: acquiring real-time frequency f of power grid system G And a preset energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN The method comprises the steps of carrying out a first treatment on the surface of the And then judging the running state of the power grid according to the acquired data, and controlling the battery pack in the energy storage device according to a judging result.
The scheme is that the real-time frequency f of the power grid is adopted G And comparing the power grid disturbance value with each critical value set in the frequency track planning interval, judging the power grid disturbance value, obtaining the required quantity of corresponding inertia support, selecting a proper energy storage battery pack according to the required quantity, and controlling the energy storage battery pack to output the stored electric energy.
The content of the frequency track planning section specifically referred to above is shown in fig. 4: taking the theoretical value of the stable frequency of the power grid as 50Hz as an example, the actual frequency of the power grid is jogged within the range of 50Hz plus or minus 0.1Hz, namely, a relatively stable lowest frequency value f of the power grid exists G_min Energy storage device starting trigger frequency f for triggering energy storage to provide inertia support on The numerical value of (2) can be according to f G_min Setting, e.g. to be equal to f G_min . If the real-time frequency f of the power grid G Greater than f on Representing that the grid is operating in a relatively stable state, i.e. the inertia supporting function of the energy storage device does not need to be activated. When the real-time frequency f of the power grid G Less than f on When the inertia supporting function of the energy storage device needs to be started, the control mode of a plurality of battery packs in the energy storage device needs to be determined according to the disturbance, namely the degree of certainty of the frequency of the power grid.
Frequency limit f when small limit frequency of power grid is missing is formulated s This value, the system frequency reference under disturbance, is also the switching frequency value chosen for replacement of the battery. As shown in connection with fig. 1 and 2, if the grid frequency drops to the safe frequency limit f s Before, i.e. when the power grid system faces a small limit frequency missing event, controlThe logic "POS" will prefer a lower cost lead acid battery pack output energy to compensate for the power deficiency. In the discharging process of the low-cost battery pack, the system frequency of the power grid can be acquired in real time, and the system frequency meets f G ≥f G_min The discharge of the low-cost battery pack is stopped. If the low-cost battery pack is completely discharged, the real-time frequency f of the power grid system G The callback is still not ideal, i.e. the relatively stable lowest frequency value f of the power grid is not reached G_min The control logic "POS" will continue to select the high cost lithium iron phosphate battery to output energy again to make up for the power loss. If the real-time power grid frequency has larger dropping degree, the safety frequency limit value f is directly broken through s After that, i.e. the grid system is facing a large-limit frequency missing event, the control logic 'POS' can indifferently start all the battery packs and output all the stored energy to make up for the power missing of the grid as much as possible.
Referring to fig. 2, in combination with fig. 4, the optimization control method of the present application includes the steps of:
first, judging whether f is satisfied G ≥f on If yes, the battery pack of the energy storage device is not started; otherwise the first set of parameters is selected,
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Controlling all battery packs in the energy storage device to start to discharge to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min And finishing inertia support, and controlling the battery pack in the energy storage device to stop discharging.
The controlling the battery pack in the energy storage device to start according to the order of low economic cost in the above steps comprises:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
Fig. 3 shows a simplified control logic block diagram of the control logic POS section of fig. 2, which is divided into three sections, consisting essentially of a decision section "Judge" and a selection section "Switch". Firstly, POS obtains a real-time frequency value f of a power grid at any time G And is connected with the energy storage device to start the trigger frequency value f on The comparison is made to determine whether the energy storage device is triggering operation for power output. Once f G Less than f on Judge1 outputs a trigger signal, switch1 receives the trigger signal to turn on the power output of Bat1, i.e. POS first selects Bat1, i.e. the lead-acid storage battery pack, to output electric energy. At the same time, switch2 also receives the trigger signal to turn on Judge2, i.e. the real-time frequency value f of the power grid G Frequency limit f for small disturbances to the grid s A size judgment link. The purpose of this is to ensure that the POS will prefer Bat1 when facing a small disturbance of the grid, and that the output work trigger of Bat2 must occur after Bat 1. Then, if the power grid frequency breaks through the frequency limit value f of small disturbance in the falling process s I.e. once f G Less than f s The Judge2 outputs a trigger signal, the Switch3 receives the trigger signal to turn on the power output of the Bat2, namely, when the power grid is disturbed to a larger extent, the POS immediately selects the Bat2, namely, the lithium iron phosphate battery pack to output electric energy, and whether the Bat1 is discharged or not is not considered. If f in the Bat1 discharge process G Always not smaller than f s Then Judge2 does not output a trigger signal, i.e. Bat2 does not turn on the discharge. Of course, the electric energy stored in Bat1 will be discharged eventually and certainly, ifAfter the electric energy of the Bat1 is discharged, the power grid frequency callback is not ideal, and the POS is required to start the Bat2 again to output power. Therefore, the POS portion also receives the Bat1 SOC signal in real time and compares it to the SOC value at which the Bat1 discharge event is completed. When Bat1 discharge is completed, i.e. socb1=0, judge3 outputs a trigger signal, and Switch4 receives the trigger signal to turn on Judge4, i.e. the real-time frequency f of the power grid G Minimum frequency value f relatively stable to the grid G_min A size judgment link. If f at this time G Not less than f G_min If the power grid frequency callback is ideal, the POS does not select Bat2 to output power; if f at this time G Less than f G_min I.e. the grid frequency callback is not ideal, POS will choose Bat2 again for power output.
Active power output P of energy storage device BESS as a whole bat The source of (2) will be selected and controlled by the POS, and P is shown in FIGS. 2 and 3 bat There are four output scenarios:
as shown in fig. 4, the frequency track planning intervals and the critical values of each interval are given to classify the frequency disturbance of the power grid, and are used as references for "judgment and selection" logic links in the "POS" power output selection control. Considering the related regulations, the allowable shortage of the power supply frequency in the normal state of the power system is as follows: if the installed capacity of the power grid is 300 kilowatts or more, the shortage is 0.2Hz; if the installed capacity of the power grid is below 300 kilowatts, the shortage is 0.5Hz. Taking a Jiangsu coastal wind farm group as an example, the installed capacity of a single wind farm is generally different in hundreds of thousands of kilowatt-hours, and the allowable frequency loss limit during grid connection can be 0.5Hz.
The lowest frequency value f of the power grid in a relatively stable state can be formulated G_min 49.9Hz, when f G_min ≤f G ≤f G_ref When the power grid is in a safe frequency interval, namely in a relative safe state. f (f) G_min Expressed as the lowest frequency value in the relatively stable state of the power grid, when f G Start to be lower than f G_min When the power grid is considered to generate relatively unsafe frequency disturbance, the energy storage device is required to provide power compensation and inertia support, so that the trigger starting frequency value f of the energy storage device for starting discharging and power output can be formulated on Equal to f G_min 49.9Hz. Taking an offshore wind power grid-connected scene as an example, because the allowable frequency loss limit of an offshore wind power plant is 0.5Hz at maximum, a cutoff frequency value f of impending danger of grid operation is formulated G_MIN If the frequency is 49.5Hz, the power system can be specified to be in a dangerous frequency interval, namely a dangerous operation state when the lowest point of the real-time frequency of the power grid is lower than 49.5Hz, namely the loss limit of the power grid frequency is larger than 0.5Hz. When f G_MIN ≤f G ＜f on When the power grid operates in a safety-lacking state requiring the energy storage device to provide virtual inertia support, a switching frequency value f of the energy storage battery in power output optimization control is set in the interval s 49.8Hz. When f s ≤f G ＜f on When the power grid frequency disturbance degree is relatively small, namely the power grid is in a small limit frequency disturbance interval; when f G_MIN ≤f G ＜f s When the power grid frequency disturbance degree is relatively large, namely the power grid is in a large limit frequency disturbance interval.
On the other hand, the wind storage parallel system is integrally connected with the grid through a three-phase inverter circuit, namely a grid-side converter, the link is a part for executing a VSG control technology, and the VSG control technology can enable the three-phase inverter circuit to simulate a motion equation of a synchronous generator rotor during grid connection so as to control the grid connection output active power of the wind storage system to finish an inertia supporting task on a power grid. If the power electronic converter of the wind storage system is a voltage type converter, a direct current bus capacitor C can be connected to a direct current bus of the wind storage system and used for buffering reactive power, protecting the inverter from instantaneous peak impact of a power grid and the like. The specific implementation of the relevant control can refer to the existing off-grid and grid-connected VSG control technology.
Effect verification
In the case of selecting two battery packs of different materials, i.e., a lead-acid storage battery and a lithium iron phosphate battery, as shown in fig. 5 and 6, the expected effect of waveform variation control of frequency and power in the process of optimizing control of wind power virtual inertia of the various energy storage battery packs is respectively given, so as to verify the feasibility of the virtual inertia optimizing control method.
The mass energy density of the lithium iron phosphate battery pack on the market is about four times that of a lead-acid battery pack, the output nominal voltage of the lithium iron phosphate battery pack is higher than that of the lead-acid battery pack, the lithium iron phosphate battery pack has no charge-discharge memory, and the price of the lithium iron phosphate battery pack is naturally more expensive. The electrical energy capacity of the lithium iron phosphate battery is theoretically higher than that of the lead acid battery under the condition of equal quality, and the electrical energy stored in the lithium iron phosphate battery is about four times that stored in the lead acid battery. Therefore, the lithium iron phosphate battery pack is more suitable for larger-amplitude frequency disturbance, and has stronger inertia supporting force and better stability during inertia supporting.
In Matlab-Simulink, modeling and simulation are carried out on the wind power virtual inertia optimization control system containing various energy storage battery packs, wherein Bat1 is a lead-acid storage battery pack, and Bat2 is a lithium iron phosphate battery pack. According to the characteristics of both batteries, the upper SOC limit of Bat2 is set to four times Bat1, and the output voltage value of Bat2 is set to two times Bat 1. Assuming that the system is operated in parallel, the system initially provides a steady active power output of 10kW to the grid step by step, while at 2.5s a slightly lower value than f is given s The frequency disturbance of the value is monitored by a POS part in the system, then all energy storage battery packs are opened to discharge, active power output of the system is increased, power compensation and inertia support are carried out on the power grid, and then the power grid frequency is adjusted back and gradually returns to a stable frequency value. As can be seen from fig. 5, by using the wind power virtual inertia optimization control system and method including multiple energy storage battery packs, when the wind power virtual inertia optimization control system and method is used for coping with power grid frequency disturbance, the required battery packs can be effectively and freely selected according to the size of the inertia support to output power, so that the high efficiency and stability of the inertia support of the system are improved, and the expected effect is ideal.
Example 2
Based on the same inventive concept as that of embodiment 1, this embodiment introduces a wind power virtual inertia optimization control device based on energy storage.
Referring to fig. 1 as well, in the controlled wind-storage combined system, a permanent magnet direct-driven fan is integrated into a power grid system after passing through a machine side converter and a grid side converter, an energy storage device is connected in parallel on a direct-current bus capacitor between the machine side converter and the grid side converter, the energy storage device comprises at least 2 groups of battery packs which are different in economic cost and can work independently, a controller and a converter are arranged in the energy storage device, the battery packs are connected into the direct-current bus between the machine side converter and the grid side converter through the converter, and the controller realizes discharge control on different battery packs through controlling the converter.
The wind power virtual inertia optimization control device of the embodiment can be realized as a controller in an energy storage device, or a wind power plant station end control, when the wind power plant station end control is realized as the controller, the station end control executes corresponding control logic to output a control instruction to the controller of the energy storage device, and the controller controls the converter according to the control instruction, so that the corresponding battery pack is controlled to discharge according to the interval where the real-time system frequency is located, and inertia support is provided.
The wind power virtual inertia optimization control device comprises:
a parameter acquisition module configured to acquire a real-time frequency f of the power grid system G And a preset energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN ；
The logic control module is configured to judge the running state of the power grid according to the acquired data, and control the battery pack in the energy storage device according to the judging result, and comprises the following steps:
judging whether or not f is satisfied G ≥f on If yes, the battery pack of the energy storage device is not started;
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfies the requirements therebetweenf G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Controlling all battery packs in the energy storage device to start to discharge to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
also included is a VSG control module configured to: and executing VSG control on the grid-side converter based on the electromechanical transient model of the synchronous generator, so that the grid-side converter can simulate inertia and damping characteristics of the synchronous generator, and control active power output by grid connection so as to provide inertia support and power compensation for a power grid system. .
Specific functional implementation of each of the functional modules described above refers to the content of the related method in embodiment 1, and is specifically noted as follows: the logic control module controls the battery pack in the energy storage device to be started in sequence from low to high according to the economic cost, and the logic control module comprises the following steps:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
Example 3
This embodiment describes a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the wind power virtual inertia optimization control method as described in embodiment 1.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The embodiments of the present application have been described above with reference to the accompanying drawings, but the present application is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present application and the scope of the claims, which are all within the protection of the present application.
Claims (10)
1. The wind power virtual inertia optimizing control method based on energy storage is characterized in that a fan is integrated into a power grid system after passing through a machine side converter and a network side converter, and an energy storage device is connected in parallel to a direct current bus capacitor between the machine side converter and the network side converter, wherein the energy storage device comprises at least 2 groups of battery packs which are different in economic cost and can work independently;
the wind power virtual inertia optimization control method comprises the following steps:
acquiring real-time frequency f of power grid system G And a preset energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN ；
Judging whether f is satisfied according to the acquired data G ≥f on If yes, the battery pack of the energy storage device is not started;
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Controlling all battery packs in the energy storage device to start to discharge to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min And finishing inertia support, and controlling the battery pack in the energy storage device to stop discharging.
2. The method of claim 1, wherein the battery packs that are economically different and are capable of operating independently of each other are battery packs that employ different materials, including lead-acid battery packs and lithium iron phosphate battery packs.
3. The method of claim 1, wherein controlling the battery pack in the energy storage device to start in a low cost to high order comprises:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
4. The method of claim 1, wherein the energy storage device is activated at a trigger frequency f on Lower limit value f of stable frequency of power grid system G_min Is equal in value.
5. The method according to claim 1, wherein the method further comprises: and executing VSG control on the grid-side converter based on the electromechanical transient model of the synchronous generator, so that the grid-side converter can simulate inertia and damping characteristics of the synchronous generator, and control active power output by grid connection so as to provide inertia support and power compensation for a power grid system.
6. The method of claim 1, wherein the energy storage device further comprises a converter and a controller, a battery being connected to a dc bus between the machine side converter and the grid side converter via the converter;
the wind power virtual inertia optimization control method is executed by the controller, and the battery pack in the energy storage device is controlled to discharge by controlling the converter.
7. The wind power virtual inertia optimizing control device based on energy storage is characterized in that a fan is integrated into a power grid system after passing through a machine side converter and a network side converter, and an energy storage device is connected in parallel to a direct current bus capacitor between the machine side converter and the network side converter, and comprises at least 2 groups of battery packs which are different in economic cost and can work independently;
the wind power virtual inertia optimization control device comprises:
a parameter acquisition module configured to acquire a real-time frequency f of the power grid system G And a preset energy storage device start trigger frequency f on System frequency reference value f under disturbance s Lower limit value f of stable frequency of power grid system G_min And a grid operation cut-off frequency f G_MIN ；
The logic control module is configured to judge the running state of the power grid according to the acquired data, and control the battery pack in the energy storage device according to the judging result, and comprises the following steps:
judging whether or not f is satisfied G ≥f on If yes, the battery pack of the energy storage device is not started;
if f G <f on And satisfy f G ≥f s The battery pack in the energy storage device is controlled to be started in order from low to high according to the economic cost so as to discharge the battery pack to the direct current bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging;
if f G <f on And satisfy f G_MIN <f G <f s Then all the batteries in the energy storage device are controlledGroup start to discharge to DC bus until the real-time frequency f of the power grid system G Lower limit value f of stable frequency of power grid system G_min Satisfy f between G ≥f G_min And finishing inertia support, and controlling the battery pack in the energy storage device to stop discharging.
8. The wind power virtual inertia optimizing control device of claim 7, wherein the logic control module controls the battery packs in the energy storage device to be started in a sequence from low to high in economic cost, comprising:
controlling the low-cost battery pack to start, comparing the real-time frequency of the power grid system with the lower limit value of the stable frequency of the power grid system in the discharging process of the battery pack, and if f is satisfied G ≥f G_min The inertia support is completed, and the battery pack in the energy storage device is controlled to stop discharging; if all low cost battery packs are discharged, and f is still not satisfied G ≥f G_min The high-cost battery pack is controlled to start until the real-time frequency of the power grid system meets f G ≥f G_min And finishing inertia support, and controlling the battery pack of the energy storage device to stop discharging.
9. The wind-powered virtual inertia optimal control device of claim 7, further comprising a VSG control module configured to: and executing VSG control on the grid-side converter based on the electromechanical transient model of the synchronous generator, so that the grid-side converter can simulate inertia and damping characteristics of the synchronous generator, and control active power output by grid connection so as to provide inertia support and power compensation for a power grid system.
10. A computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements a wind power virtual inertia optimization control method according to any one of claims 1-6.
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