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CN-122026402-A - Energy storage power station frequency modulation method under control of virtual synchronous machine

CN122026402ACN 122026402 ACN122026402 ACN 122026402ACN-122026402-A

Abstract

The invention relates to the technical field of operation and control of electric power systems, and discloses a frequency modulation method of an energy storage power station under the control of a virtual synchronous machine, wherein the energy storage power station is connected with an alternating current power grid through a virtual synchronous machine control converter and consists of a plurality of energy storage units connected in parallel through a public direct current bus; S1, power grid frequency tracking and instruction generation, namely controlling a converter based on a virtual synchronous machine, sensing the frequency of an alternating current power grid, and generating a primary frequency modulation active power instruction according to the frequency. According to the invention, the direct-current bus voltage deviation is used as a core control variable, and a deviation threshold-based dual-mode dynamic decision mechanism is set, so that the disturbance intensity can be rapidly identified within millisecond time when the power grid frequency disturbance occurs, and the rapid power support mode can be immediately entered, so that the fastest and most sufficient response to the power shortage is realized, the frequency minimum point is remarkably improved, the frequency drop rate is effectively restrained, and the system recovery time is shortened.

Inventors

  • HE JIANRONG
  • WANG YONG

Assignees

  • 合邦电力科技有限公司

Dates

Publication Date
20260512
Application Date
20260413

Claims (10)

  1. 1. The energy storage power station frequency modulation method under the control of the virtual synchronous machine is characterized in that the energy storage power station is connected with an alternating current power grid through a virtual synchronous machine control converter and consists of a plurality of energy storage units connected in parallel through a public direct current bus, and the method executes the following control flow: S1, grid frequency tracking and instruction generation, namely controlling a converter based on a virtual synchronous machine, sensing the frequency of an alternating current grid, and generating a primary frequency modulation active power instruction according to the frequency; s2, setting a direct current side target voltage, namely integrating a primary frequency modulation active power instruction and the actual output power of the energy storage power station, and setting a target voltage reference value of a public direct current bus; s3, dynamically deciding an operation mode, namely dynamically switching between a fast power support mode and a state of charge equalization mode according to the deviation between the real-time voltage of the public direct current bus and a target voltage reference value of the public direct current bus and a preset threshold condition; S4, power multi-mode coordination distribution, namely generating corresponding power distribution instructions for all energy storage units according to the operation mode determined in the step S3, wherein the rapid power support mode takes the maximum frequency modulation response speed as a priority target, and the state-of-charge equalization mode takes the state of charge of each energy storage unit as a priority target; And S5, performing power instruction execution and closed-loop control, namely adjusting the charge and discharge power of each energy storage unit through local control according to the power instruction distributed by each energy storage unit, so that the actual voltage of the common direct current bus is stabilized near a target voltage reference value, and realizing active support of the total output power of the energy storage power station on the frequency of the power grid.
  2. 2. The method according to claim 1, wherein the power-voltage droop relationship according to which the target voltage reference value is set in the step S2 is: , Wherein, the As a reference value for the voltage, the reference value, Is the rated voltage of the public direct current bus, For a target total active power containing a primary frequency modulation instruction, The active power is rated to be output for the energy storage power station, Is a sagging coefficient, and <0。
  3. 3. The method of claim 2, wherein the sag factor The value of the energy storage power station is dynamically adjusted by the equivalent inertia time constant and the frequency modulation dead zone set value of the on-line identification, specifically, when the identified equivalent inertia time constant is reduced, I is increased I is reduced when the frequency modulation dead zone set value is reduced And (3) taking the value, so that the suppression capability of the high-frequency disturbance component of the power grid is adaptively enhanced on the premise of maintaining the stability of the direct-current voltage.
  4. 4. The method according to claim 1, wherein in the step S4, in the fast power support mode, the current maximum chargeable and dischargeable power capacity according to which the power command is allocated to each energy storage unit is updated in real time by an online optimization model including dynamic relaxation variables, the model uses the total available power adjustment margin of the whole energy storage units as an optimization target, uses the state of charge safety interval, the temperature limit value and the instantaneous overload capacity of the converter of each unit as constraints, and solves and updates the capacity value every short period.
  5. 5. The method according to claim 1, wherein the amount of compensation power allocated to each energy storage unit in the state of charge equalization mode in step S4 is not only positively related to the degree to which the state of charge of the unit deviates from the average, but also negatively related to the current accumulated charge-discharge cycle fatigue of the unit, wherein the fatigue F is evaluated according to the following formula: , Wherein, the For the accumulated throughput capacity of the energy storage unit, For the purpose of its rated capacity, As the weight coefficient of the light-emitting diode, And the average charge-discharge multiplying power is obtained according to the historical operation data statistics of the unit.
  6. 6. The method of claim 1, wherein the local control of each energy storage unit in step S5 adopts an anti-saturation adaptive voltage outer loop structure based on an interference observer, the structure estimates and feed-forward compensates the common DC bus voltage coupling interference caused by the power mutation of the adjacent units in real time through the interference observer, and automatically adjusts the voltage loop controller parameters to prevent integral saturation when the local power command reaches the limit.
  7. 7. The method according to claim 1, wherein in step S1, a feedforward compensation term based on the prediction of the rate of change of frequency is introduced when generating the primary active power command, and specifically comprising the steps of: S1a, acquiring alternating current power grid frequency sampling values of a plurality of control periods of a current preamble and a preamble in real time; S1b, constructing and solving a least square fitting curve describing the current dynamic process of the system, and taking the slope of the curve as a predicted value of the power grid frequency change rate in a future control period; s1c, acquiring total available rotary spare capacity of the energy storage power station at the current moment; s1d, multiplying the frequency change rate predicted in the step S1b by a dynamic gain coefficient proportional to the total available rotation reserve capacity in the step S1c to obtain the feedforward compensation term; S1e, superposing the feedforward compensation item on a fundamental wave instruction generated based on an active-frequency droop control link to jointly form the primary frequency modulation active power instruction; wherein the dynamic gain coefficient Determined by the following formula: , In the formula, In order to adjust the proportionality coefficient, For the total available rotational reserve capacity at the current time acquired in step S1c, Is the rated power of the energy storage power station.
  8. 8. The method of claim 1, wherein the step S2 of obtaining the actual output power of the energy storage power station is implemented by a multi-rate data fusion method, and specifically includes that high-speed sampling and processing are performed on the ac side electrical quantity of the control converter of the virtual synchronous machine to obtain a first power estimation, low-speed sampling and processing are performed on the dc side electrical quantity of each energy storage unit to obtain a second power estimation, and then the first power estimation and the second power estimation are fused by using a kalman filter to obtain an actual output power value for setting a target voltage reference value.
  9. 9. The method according to claim 1, wherein the threshold condition preset in the step S3 is adaptively adjusted according to the dynamic process of the grid frequency, in which the threshold is adjusted to extend the triggering range of the fast power support mode in the initial stage of the rapid change of the grid frequency, and in which the threshold is adjusted to extend the triggering range of the state of charge equalization mode in the recovery stage of the frequency tending to stabilize.
  10. 10. The method of claim 1, wherein the steps S3 and S4 are performed using a hybrid driving mechanism of event triggering and time triggering, wherein the mode decision and power allocation are triggered immediately when a significant change of the absolute value of the common dc bus voltage deviation across a preset threshold is detected, and the periodic triggering is performed with a preset basic period if there is no significant change.

Description

Energy storage power station frequency modulation method under control of virtual synchronous machine Technical Field The invention relates to the technical field of operation and control of power systems, in particular to a frequency modulation method of an energy storage power station under the control of a virtual synchronous machine. Background With the large-scale grid connection of high-proportion renewable energy sources represented by wind power and photovoltaics, the inertia level and the frequency regulation capability of an electric power system are obviously weakened, in order to solve the challenge, the virtual synchronous machine technology is widely applied to power electronic interface equipment such as an energy storage converter and the like, virtual inertia and damping are provided for the system through a rotor motion equation of an analog synchronous generator, so that the frequency of a power grid is supported stably, however, the traditional virtual synchronous machine control method has inherent limitations when dealing with rapid and large-scale power disturbance of the power grid, and a typical improvement scheme, such as a 'model prediction virtual synchronous machine control-based energy storage frequency modulation method' disclosed by an authorized bulletin No. CN113890055B, is characterized in that rolling optimization is performed by establishing a cost function containing frequency increment and power increment and utilizing model prediction control so as to improve the frequency dynamic characteristic. Disclosure of Invention The invention aims to provide an energy storage power station frequency modulation method under the control of a virtual synchronous machine so as to solve the problems in the background technology. The energy storage power station frequency modulation method under the control of the virtual synchronous machine, wherein the energy storage power station is connected with an alternating current power grid through a virtual synchronous machine control converter and consists of a plurality of energy storage units connected in parallel through a public direct current bus; the method executes the following control flow: S1, grid frequency tracking and instruction generation, namely controlling a converter based on a virtual synchronous machine, sensing the frequency of an alternating current grid, and generating a primary frequency modulation active power instruction according to the frequency; s2, setting a direct current side target voltage, namely integrating a primary frequency modulation active power instruction and the actual output power of the energy storage power station, and setting a target voltage reference value of a public direct current bus; s3, dynamically deciding an operation mode, namely dynamically switching between a fast power support mode and a state of charge equalization mode according to the deviation between the real-time voltage of the public direct current bus and a target voltage reference value of the public direct current bus and a preset threshold condition; S4, power multi-mode coordination distribution, namely generating corresponding power distribution instructions for all energy storage units according to the operation mode determined in the step S3, wherein the rapid power support mode takes the maximum frequency modulation response speed as a priority target, and the state-of-charge equalization mode takes the state of charge of each energy storage unit as a priority target; And S5, performing power instruction execution and closed-loop control, namely adjusting the charge and discharge power of each energy storage unit through local control according to the power instruction distributed by each energy storage unit, so that the actual voltage of the common direct current bus is stabilized near a target voltage reference value, and realizing active support of the total output power of the energy storage power station on the frequency of the power grid. As a preferred technical solution of the present invention, the power-voltage droop relationship according to which the target voltage reference value is set in the step S2 is as follows: , Wherein, the As a reference value for the voltage, the reference value,Is the rated voltage of the public direct current bus,For a target total active power containing a primary frequency modulation instruction,The active power is rated to be output for the energy storage power station,Is a sagging coefficient, and<0。 As a preferable embodiment of the invention, the sagging coefficientThe value of the energy storage power station is dynamically adjusted by the equivalent inertia time constant and the frequency modulation dead zone set value of the on-line identification, specifically, when the identified equivalent inertia time constant is reduced, I is increasedI is reduced when the frequency modulation dead zone set value is reducedAnd (3) taking the value, so that the suppression ca