New energy plant station power control method and device based on inertia support

Abstract

The embodiment of the invention relates to a new energy plant station power control method and device based on inertia support. The method comprises the steps that the current operation frequency and the current power of an alternating current system are detected; calculating the total power P of the new energy plant station for inertia support based on the current operation frequency and the current power; obtaining power parameters of each device of the new energy plant station; power direction discrimination is carried out based on the total power P of the new energy plant station and the power parameters of the devices of the new energy plant station; and power distribution is carried out based on a power direction discrimination result. According to the technical scheme provided by the embodiment of the invention, the inertia output of each device under different inertia support conditions is determined according to the capacity requirement and the network topology of each device in the new energy plant station, so that the accurate processing of each device is ensured, and the inertia capability of the new energy plant station is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of power system power control, and in particular to a power control method and device for a new energy plant based on inertial support. Background Art

[0003] At present, the secondary frequency regulation engineering field often allocates the output power of each unit in proportion to the adjustable capacity. This method is called proportional allocation, but this strategy cannot meet the optimal control requirements of the system. In addition, most of the current research on wind and solar energy participating in frequency regulation focuses on the design of controllers, the control strategies of wind farms and photovoltaic power stations themselves, and less on the coordinated control between wind and solar energy and other frequency regulation resources.

[0004] In recent years, in order to make new energy systems also have the characteristics of inertia and damping, scholars have found that virtual synchronous machine control can simulate the advantages of inertia and damping of traditional power systems. At the same time, it can realize multiple functions such as frequency regulation, voltage regulation, power distribution, etc., which greatly improves the stability of the system. At present, microgrid systems generally use multiple units in parallel to connect, but if the connection impedance and equivalent output impedance value between each VSG are different, there will be problems such as circulating reactive power and difficulty in sharing reactive power, which will reduce the stability of the system and damage the power electronic devices. Summary of the invention

[0005] Based on the above situation of the prior art, the purpose of the embodiments of the present invention is to provide a new energy plant power control method and device based on inertia support, which determines the inertia output of each device under different inertia support conditions according to the capacity requirements of each device in the new energy plant and the network topology, thereby ensuring the accurate output of each device and improving the inertia capacity of the new energy plant.

[0006] To achieve the above object, according to a first aspect of the present invention, a power control method for a new energy plant based on inertial support is provided, wherein the new energy plant is connected to an AC system, and the method comprises the steps of:

[0007] Detect the current operating frequency and current power of the AC system;

[0008] Calculate the total power P of the new energy plant for inertia support based on the current operating frequency and the current power;

[0009] Obtain the power parameters of each device in the new energy plant;

[0010] Power direction determination is performed based on the total power P of the new energy plant and the power parameters of each device of the new energy plant;

[0011] Power is allocated based on the result of power direction determination.

[0012] Further, the total power of the new energy plant for inertia support is calculated based on the current operating frequency and the current power, including calculating the total power P of the new energy plant for inertia support according to the following formula:

[0013]

[0014] Where f0 represents the current operating frequency of the AC system, fref represents the preset frequency reference value, G s represents the inertia control transfer function, and P0 represents the current power of the AC system.

[0015] Further, the new energy plant station includes new energy power generation equipment, energy storage equipment and a static VAR generator SVG, the new energy power generation equipment includes at least one new energy inverter, and the energy storage equipment includes at least one energy storage inverter;

[0016] The power parameters of each device in the new energy plant include the maximum active power P output by the new energy inverter. nmax , the maximum active power P of the energy storage inverter smax ; When inertia support is needed, the active power P output by the new energy inverter is n0 , the active power output capacity P of the energy storage system s0 ; Minimum operating active power P of new energy inverter nmin , the minimum active power P of the energy storage inverter smin .

[0017] Furthermore, the power direction is determined based on the total power P of the new energy plant and the power parameters of each device of the new energy plant, including:

[0018] Based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, as well as the relationship between the difference ΔP and the power parameters of each equipment in the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated; wherein the difference ΔP represents the difference between the total power P of the new energy plant and the current power P0 of the AC system.

[0019] Further, based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, and the relationship between the difference ΔP and the power parameters of each device of the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated, including determining the power of the new energy power generation equipment according to the following formula:

[0020] When P>P0,

[0021]

[0022] When P≤P0,

[0023]

[0024] Among them, P n Indicates the active power command value of the new energy inverter.

[0025] Further, based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, and the relationship between the difference ΔP and the power parameters of each device of the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated, including determining the power of the energy storage equipment according to the following formula:

[0026] When P>P0,

[0027]

[0028] When P≤P0,

[0029]

[0030] Among them, P s Indicates the active power command value of the energy storage inverter.

[0031] Furthermore, power allocation is performed based on the result of power direction determination, including:

[0032] Based on the determined power of the new energy power generation equipment, the active power command value of each new energy inverter is set according to the following formula:

[0033]

[0034] Among them, P nref Represents the active power command value of a single new energy inverter, Z i It represents the impedance from the new energy inverter to the PCC common connection point, and x represents the number of new energy inverters in the plant.

[0035] Furthermore, power allocation is performed based on the result of power direction determination, including:

[0036] Based on the determined power of the new energy power generation equipment, the active power command value of each energy storage inverter is set according to the following formula:

[0037]

[0038] Among them, P sref It represents the active power command value of a single energy storage inverter, and n represents the number of energy storage inverters in the plant.

[0039] Furthermore, the power distribution based on the result of power direction determination also includes controlling the reactive power output by the static VAR generator SVG:

[0040] If Q0 max ,but

[0041] If Q0 ≥ Q max , then Q ref =Q max ;

[0042] Among them, Q ref Indicates the reactive power command value output by the static VAR generator SVG, Q0 indicates the current reactive power of the static VAR generator SVG, Q max Indicates the maximum output reactive power of the static VAR generator SVG, U ref Indicates the AC voltage reference value of the AC system, G g Indicates the voltage regulation factor.

[0043] According to another aspect of the present invention, a power control device for a new energy plant based on inertial support is provided, wherein the new energy plant is connected to an AC system, and the device comprises:

[0044] An operation detection module is used to detect the current operating frequency and current power of the AC system;

[0045] A total power acquisition module, used to calculate the total power P of the new energy plant for inertia support based on the current operating frequency and the current power;

[0046] Equipment parameter acquisition module, used to obtain the power parameters of each equipment in the new energy plant;

[0047] A power direction determination module, used for determining the power direction based on the total power P of the new energy plant and the power parameters of each device of the new energy plant;

[0048] The power distribution module is used to distribute power based on the result of power direction determination.

[0049] ​In summary, the embodiment of the present invention provides a power control method and device for a new energy plant based on inertia support, the method comprising the steps of: detecting the current operating frequency and current power of the AC system; calculating the total power P of the new energy plant for inertia support based on the current operating frequency and current power; obtaining the power parameters of each device in the new energy plant; determining the power direction based on the total power P of the new energy plant and the power parameters of each device in the new energy plant; and allocating power based on the result of the power direction determination. The technical solution provided by the embodiment of the present invention, on the one hand, determines the output priority and capacity requirements of each inertia support device by determining the spare capacity of each device in the new energy plant, comprehensively considers various factors, determines the inertia output of each device under different inertia support conditions, and gives full play to the inertia capacity of the new energy plant; on the other hand, through the determined inertia capacity of each device in the new energy plant, according to the network topology of the new energy plant, the output of each unit inertia support is determined, thereby achieving the accurate output of each unit module in each device. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the overall configuration of the new energy plant;

[0051] Figure 2 It is a flow chart of a new energy plant power control method based on inertial support provided by an embodiment of the present invention;

[0052] Figure 3 It is a control block diagram of a new energy plant power control method based on inertial support provided by an embodiment of the present invention;

[0053] Figure 4 It is a control block diagram for active power control in the prior art;

[0054] Figure 5 It is a control block diagram for reactive power control in the prior art. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0056] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in one or more embodiments of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0057] At present, the inertia support capacity of new energy plants in the engineering field mainly considers the energy storage equipment configured in the new energy plants, but cannot play the role of the overall inertia support of the new energy system, including the inertia adjustment capability of the new energy inverter and SVG inverter. Usually, the inertia link and damping link are set for active power, and the droop coefficient is considered for reactive power. By detecting the changes in active power and reactive power, the AC frequency and AC voltage are adjusted, and a certain inertia time constant is given during the adjustment process to simulate the change characteristics of traditional generators. Figure 4 The control block diagram for active power control is shown in FIG. Figure 5 A control block diagram for reactive power control is shown in FIG.

[0058] The above-mentioned virtual inertia control method can ensure the stable output of the virtual inertia of a single new energy equipment system. However, in a multi-parallel system, it is impossible to accurately guarantee the virtual inertia output of each unit, and even cause oscillation and circulation between the devices in the system. At the same time, the current system only considers the inertia support capacity of the energy storage equipment, and does not comprehensively consider the overall external effect of the inertia support capacity of the new energy power generation equipment and the static VAR generator SVG, and cannot give full play to the inertia support capacity of the new energy plant. In response to the above technical problems, an embodiment of the present invention provides a new energy plant power control method and device based on inertia support.

[0059] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. An embodiment of the present invention provides a power control method for a new energy plant based on inertial support. Figure 1 The overall configuration diagram of the new energy plant is shown in Figure . Figure 1As shown, the new energy plant station includes new energy power generation equipment, energy storage equipment and static VAR generator SVG. Among them, the new energy power generation equipment is, for example, wind power generation equipment, photovoltaic power generation equipment, etc., and each new energy power generation equipment includes at least one new energy inverter. The energy storage equipment includes at least one energy storage inverter, which is used to smooth the voltage output from the new energy power generation equipment to the AC system. The new energy plant station is interconnected with the AC system through the busbar. The PCC point of the new energy plant station is the point of common coupling, which usually refers to the load connection point of more than one user in the power system.

[0060] Figure 2 FIG. 4 is a flow chart of a method for controlling power of a new energy plant based on inertial support according to an embodiment of the present invention. Figure 3 FIG. 4 is a control block diagram of a power control method for a new energy plant based on inertial support according to an embodiment of the present invention. Figure 2 and Figure 3 As shown, the method comprises the following steps:

[0061] S202: Detect the current operating frequency and current power of the AC system. The current operating frequency and current power of the AC system can be obtained by detecting parameters such as the operating voltage and the operating current of the AC system.

[0062] S204, calculating the total power P of the new energy plant for inertial support based on the current operating frequency and current power. According to the current operating frequency and current power of the AC system,

[0063] f ref =f0-G s (P-P0)

[0064] Where f0 represents the current operating frequency of the AC system, fref represents the preset frequency reference value, G s represents the inertia control transfer function, and P0 represents the current power of the AC system.

[0065] The above formula can be used to obtain the total power P of the new energy plant for inertia support:

[0066]

[0067] S206: Obtain power parameters of each device in the new energy plant. The power parameters of each device in the new energy plant include the maximum active power P output by the new energy inverter. nmax , the maximum active power P of the energy storage inverter smax ; When inertia support is needed, the active power P output by the new energy inverter is n0 , the active power output capacity P of the energy storage system s0; Minimum operating active power P of new energy inverter nmin , the minimum active power P of the energy storage inverter smin .

[0068] S208. Determine the power direction based on the total power P of the new energy plant and the power parameters of each device in the new energy plant. In this embodiment of the present invention, the power of the new energy power generation equipment and the energy storage equipment is allocated based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, and the relationship between the difference ΔP and the power parameters of each device in the new energy plant; wherein the difference ΔP represents the difference between the total power P of the new energy plant and the current power P0 of the AC system. Specifically, the allocation can be performed according to the following formula:

[0069] When P>P0,

[0070]

[0071] When P≤P0,

[0072]

[0073] Among them, P n Represents the active power command value of the new energy inverter, P s Indicates the active power command value of the energy storage inverter.

[0074] In the embodiment of the present invention, by determining the output priority and capacity requirements of inertia-supported new energy equipment, energy storage equipment and SVG, various factors are comprehensively considered, and the inertia output of each device is determined under different inertia support conditions, so that the inertia capacity of the new energy plant can be fully utilized.

[0075] S210, perform power distribution based on the result of power direction determination. Through the above calculation, the power distribution ratio of the energy storage device and the new energy device can be determined, and based on the distribution ratio result, the active power of each new energy inverter and energy storage inverter in the energy storage device and the new energy device can be set.

[0076] The active power of the new energy inverter is set based on the power of the determined new energy equipment. Considering the distributed characteristics of new energy equipment, the influence of the wiring impedance of distributed new energy equipment on power distribution needs to be considered. The active power command value of each new energy inverter is set according to the following formula:

[0077]

[0078] Among them, P nref Represents the active power command value of a single new energy inverter, Z iIt represents the impedance from the new energy inverter to the PCC common connection point, and x represents the number of new energy inverters in the plant.

[0079] The active power of the energy storage inverter is set based on the determined power of the energy storage device. Since the energy storage device is usually configured in a centralized manner, the power of each energy storage inverter of the energy storage device can be distributed in a power-sharing manner. The active power command value of each energy storage inverter is set according to the following formula:

[0080]

[0081] Among them, P sref It represents the active power command value of a single energy storage inverter, and n represents the number of energy storage inverters in the plant.

[0082] The above distribution method provided in the embodiment of the present invention is used to distribute power to each inverter of the new energy equipment and the energy storage equipment, and determine the output of the inertia support of each unit, so as to ensure the accurate output of each inverter unit.

[0083] According to some optional embodiments, the power distribution is performed based on the result of the power direction determination, and further includes controlling the reactive power output by the static VAR generator SVG:

[0084] If Q0 max ,but

[0085] If Q0 ≥ Q max , then Q ref =Q max ;

[0086] Among them, Q ref Indicates the reactive power command value output by the static VAR generator SVG, Q0 indicates the current reactive power of the static VAR generator SVG, Q max Indicates the maximum output reactive power of the static VAR generator SVG, U ref Indicates the AC voltage reference value of the AC system, G g Indicates the voltage regulation factor.

[0087] An embodiment of the present invention further provides a new energy plant power control device based on inertial support, wherein the new energy plant is connected to an AC system, and the device comprises:

[0088] An operation detection module is used to detect the current operating frequency and current power of the AC system;

[0089] A total power acquisition module, used to calculate the total power P of the new energy plant for inertia support based on the current operating frequency and the current power;

[0090] ​Equipment parameter acquisition module, used to obtain the power parameters of each equipment in the new energy plant;

[0091] A power direction determination module, used for determining the power direction based on the total power P of the new energy plant and the power parameters of each device of the new energy plant;

[0092] The power distribution module is used to distribute power based on the result of power direction determination.

[0093] Among them, the specific process of each module in the inertial support-based new energy plant power control device to realize its function is the same as the steps of the inertial support-based new energy plant power control method involved in the above-mentioned embodiment of the present invention, and its repeated description will be omitted here.

[0094] In summary, the embodiment of the present invention relates to a power control method and device for a new energy plant based on inertia support, the method comprising the steps of: detecting the current operating frequency and current power of the AC system; calculating the total power P of the new energy plant for inertia support based on the current operating frequency and current power; obtaining the power parameters of each device in the new energy plant; determining the power direction based on the total power P of the new energy plant and the power parameters of each device in the new energy plant; and allocating power based on the result of the power direction determination. The technical solution provided by the embodiment of the present invention, on the one hand, determines the output priority and capacity requirements of each inertia support device by determining the spare capacity of each device in the new energy plant, comprehensively considers various factors, determines the inertia output of each device under different inertia support conditions, and gives full play to the inertia capacity of the new energy plant; on the other hand, through the determined inertia capacity of each device in the new energy plant, according to the network topology of the new energy plant, determines the output of each unit inertia support, thereby achieving the accurate output of each unit module in each device.

[0095] It should be understood that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention (including claims) is limited to these examples; under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of one or more embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. The above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A power control method for a new energy plant based on inertia support, characterized in that: The new energy plant is connected to an AC system, and the method comprises the steps of: Detect the current operating frequency and current power of the AC system; Calculate the total power P of the new energy plant for inertia support based on the current operating frequency and the current power; Obtain the power parameters of each device in the new energy plant; Power direction determination is performed based on the total power P of the new energy plant and the power parameters of each device of the new energy plant; Power is allocated based on the result of power direction determination.

2. The method according to claim 1, characterized in that: The total power of the new energy plant for inertia support is calculated based on the current operating frequency and the current power, including calculating the total power P of the new energy plant for inertia support according to the following formula: Where f0 represents the current operating frequency of the AC system, fref represents the preset frequency reference value, G s represents the inertia control transfer function, and P0 represents the current power of the AC system.

3. The method according to claim 1, characterized in that The new energy plant station includes a new energy power generation device, an energy storage device and a static VAR generator SVG, wherein the new energy power generation device includes at least one new energy inverter, and the energy storage device includes at least one energy storage inverter; The power parameters of each device in the new energy plant include the maximum active power P output by the new energy inverter. nmax , the maximum active power P of the energy storage inverter smax ; When inertia support is needed, the active power P output by the new energy inverter is n0 , the active power output capacity P of the energy storage system s0 ; Minimum operating active power P of new energy inverter nmin , the minimum active power P of the energy storage inverter smin .

4. The method according to claim 3, characterized in that: The power direction is determined based on the total power P of the new energy plant and the power parameters of each device of the new energy plant, including: Based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, as well as the relationship between the difference ΔP and the power parameters of each equipment in the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated; wherein the difference ΔP represents the difference between the total power P of the new energy plant and the current power P0 of the AC system.

5. The method according to claim 4, characterized in that Based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, and the relationship between the difference ΔP and the power parameters of each device of the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated, including determining the power of the new energy power generation equipment according to the following formula: When P>P0, When P≤P0, Among them, P n Indicates the active power command value of the new energy inverter.

6. The method according to claim 4, characterized in that Based on the relationship between the total power P of the new energy plant and the current power P0 of the AC system, and the relationship between the difference ΔP and the power parameters of each device of the new energy plant, the power of the new energy power generation equipment and the energy storage equipment is allocated, including determining the power of the energy storage equipment according to the following formula: When P>P0, When P≤P0, Among them, P s Indicates the active power command value of the energy storage inverter.

7. The method according to claim 5, characterized in that Power allocation is performed based on the result of power direction determination, including: Based on the determined power of the new energy power generation equipment, the active power command value of each new energy inverter is set according to the following formula: Among them, P nref Represents the active power command value of a single new energy inverter, Z i It represents the impedance from the new energy inverter to the common connection point PCC, and x represents the number of new energy inverters in the plant.

8. The method according to claim 6, characterized in that Power allocation is performed based on the result of power direction determination, including: Based on the determined power of the new energy power generation equipment, the active power command value of each energy storage inverter is set according to the following formula: Among them, P sref It represents the active power command value of a single energy storage inverter, and n represents the number of energy storage inverters in the plant.

9. The method according to claim 7 or 8, characterized in that: Power distribution is performed based on the result of power direction determination, and the reactive power output by the static VAR generator SVG is controlled: If Q0 max ,but ​ If Q0 ≥ Q max , then Q ref =Q max ; Among them, Q ref Indicates the reactive power command value output by the static VAR generator SVG, Q0 indicates the current reactive power of the static VAR generator SVG, Q max Indicates the maximum output reactive power of the static VAR generator SVG, U ref Indicates the AC voltage reference value of the AC system, G g Indicates the voltage regulation factor.

10. A new energy plant power control device based on inertial support, characterized in that: The new energy plant is connected to an AC system, and the device includes: An operation detection module is used to detect the current operating frequency and current power of the AC system; A total power acquisition module, used to calculate the total power P of the new energy plant for inertia support based on the current operating frequency and the current power; Equipment parameter acquisition module, used to obtain the power parameters of each equipment in the new energy plant; A power direction determination module, used for determining the power direction based on the total power P of the new energy plant and the power parameters of each device of the new energy plant; The power distribution module is used to distribute power based on the result of power direction determination.

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