Cooperative control method and device for new energy system

Abstract

The present specification relates to the technical field of new energy power generation, and specifically discloses a kind of new energy system's coordinated control method and device, wherein the method comprises: obtaining the system network parameters and operating parameters of new energy system, new energy output fluctuation parameters and system power angle oscillation parameters;Based on the system network parameters and operating parameters of new energy system, new energy output fluctuation parameters and system power angle oscillation parameters, the operating short-circuit ratio before new energy grid-connected point fault and the boundary short-circuit ratio under voltage safety constraint are calculated;In the case where new energy system fault is cleared, according to the operating short-circuit ratio and boundary short-circuit ratio, combined with the new energy output fluctuation parameters and system power angle oscillation parameters, the active and reactive power coordinated control scheme of wind turbine is determined.The above-mentioned scheme can improve the voltage safety of new energy sending terminal system, and inhibit the repeated low penetration caused by voltage fluctuation.

Description

Technical Field

[0001] This specification relates to the field of new energy power generation technology, and in particular to a collaborative control method and device for a new energy system. Background Technology

[0002] With the development of new energy power generation, it plays a crucial role in carbon emission reduction and electricity supply. However, the large-scale grid connection of new energy sources increases the complexity of power system operation and poses new challenges to its safety and stability. When a system fault occurs, wind turbines generate reactive power under low-voltage ride-through control to support voltage recovery, while simultaneously reducing active power output to prevent overcurrent. After the fault is cleared, the low-voltage ride-through mode ends, the reactive power is quickly withdrawn, and active power gradually recovers. During this process, the switching of transient control of wind turbines and the power angle stability of the sending-end synchronous generator both affect the steady-state safety of the wind turbine grid connection point voltage. On the one hand, the withdrawal of reactive power compensation and the recovery of large-scale active power transmission may cause steady-state voltage safety issues; on the other hand, the shift in power angle between the sending-end and receiving-end synchronous generators can also cause a drop in the wind turbine grid connection point voltage. When the wind turbine grid connection point voltage drops below 0.9, low-voltage ride-through will be triggered again. Voltage fluctuations can lead to repeated low-voltage ride-throughs, which may even cause the unit to disconnect from the grid in severe cases.

[0003] Most transient control strategies for renewable energy units comprehensively consider the withstand capability of grid-connected converters and the reactive power support of the units to the system, aiming to improve the transient voltage stability of the system. Currently, there is no coordinated control strategy for renewable energy that comprehensively considers the transient power angle stability of the sending-end synchronous generator units and the voltage fluctuation problem at the renewable energy generator terminals.

[0004] There is currently no effective solution to the above problems. Summary of the Invention

[0005] This specification provides a collaborative control method and device for a new energy system to solve the technical problems of voltage insecurity or continuous power angle oscillation that may occur in the constant voltage or constant power control of wind turbines after fault clearance in the prior art.

[0006] This specification provides an embodiment of a collaborative control method for a new energy system, including:

[0007] Obtain the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system;

[0008] Based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system and the power angle oscillation parameters of the system, the operating short-circuit ratio before the fault at the grid connection point of the new energy and the boundary short-circuit ratio under voltage safety constraints are calculated.

[0009] When the fault in the new energy system is cleared, the active and reactive power coordinated control scheme of the wind turbine is determined based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters.

[0010] In one embodiment, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the system power angle oscillation parameters, the operating short-circuit ratio before the fault at the new energy grid connection point and the boundary short-circuit ratio under voltage safety constraints are calculated, including:

[0011] Calculate the operating short-circuit ratio and the boundary short-circuit ratio using the following formulas:

[0012]

[0013]

[0014]

[0015]

[0016]

[0017] Where OSCR is the operating short-circuit ratio, CSCR is... _0.9 P is the boundary short-circuit ratio. s Before the wind turbine failed, it had active power output, x d x is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; l δ is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; δ is the power angle of the sending-end synchronous generator relative to the receiving-end system; θ is the phase angle of the voltage at the wind turbine grid connection point.

[0018] In one embodiment, based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the renewable energy output fluctuation parameters and the system power angle oscillation parameters, a wind turbine active and reactive power coordinated control scheme is determined, including:

[0019] Determine whether the operating short-circuit ratio is greater than the boundary short-circuit ratio;

[0020] If it is determined that the operating short-circuit ratio is greater than the boundary short-circuit ratio, the active power priority control scheme is determined to be the wind turbine active power and reactive power coordinated control scheme.

[0021] If it is determined that the operating short-circuit ratio is not greater than the boundary short-circuit ratio, the reactive power priority control scheme is determined as the wind turbine active and reactive power coordinated control scheme.

[0022] The active power priority control scheme and the reactive power priority control scheme are pre-set based on the power output fluctuation parameters of the new energy source and the power angle oscillation parameters of the system.

[0023] In one embodiment, the active power priority control scheme includes:

[0024] I pref =I p_original -MK1ω-a;

[0025]

[0026] Among them, I pref I is the reference value for the active current of the wind turbine. p_original The original power control command is ω, where ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator, M is the inertia of the sending-end synchronous generator, and K1 is the adjustment parameter, which is set to K1>0.

[0027] I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3。

[0028] In one embodiment, the reactive power priority control scheme includes:

[0029] I qref =K2(1-V)I N ;

[0030]

[0031] Among them, I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3;

[0032] I pref I is the reference value for the active current of the wind turbine. p_original The original power control command is ω, where ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator, M is the inertia of the sending-end synchronous generator, and K1 is the adjustment parameter, which is set to K1>0.

[0033] In one embodiment, after determining the active and reactive power coordinated control scheme of the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters, the method further includes:

[0034] The aforementioned active and reactive power coordinated control scheme for the wind turbine is executed to perform coordinated control.

[0035] The collaborative control ends when the preset conditions are met.

[0036] In one embodiment, the preset condition includes at least one of the following:

[0037] The voltage error is within the preset range;

[0038] The control time exceeds the preset time limit.

[0039] This specification also provides a collaborative control device for a new energy system, comprising:

[0040] The acquisition module is used to acquire the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system.

[0041] The calculation module is used to calculate the operating short-circuit ratio before the fault at the grid connection point of the new energy system and the boundary short-circuit ratio under voltage safety constraints, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system and the system power angle oscillation parameters.

[0042] The determination module is used to determine the active and reactive power coordinated control scheme of the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the power output fluctuation parameters of the new energy system and the power angle oscillation parameters, when the fault of the new energy system is cleared.

[0043] This specification also provides a computer device, including a processor and a memory for storing processor-executable instructions, wherein the processor executes the instructions to implement the steps of the collaborative control method for the new energy system described in any of the above embodiments.

[0044] This specification also provides a computer-readable storage medium storing computer instructions that, when executed, implement the steps of the collaborative control method for the new energy system described in any of the above embodiments.

[0045] This specification provides a method for coordinated control of a new energy system. It acquires the system network parameters and operating parameters, new energy output fluctuation parameters, and system power angle oscillation parameters of the new energy system. Based on these parameters, the method calculates the operating short-circuit ratio before a grid connection point fault and the boundary short-circuit ratio under voltage safety constraints. After the new energy system fault is cleared, a coordinated active and reactive power control scheme for the wind turbine is determined based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters. In this embodiment, by comparing the operating short-circuit ratio of the new energy grid-connected system with the boundary short-circuit ratio constrained by voltage safety, a control strategy prioritizing active or reactive power is switched to, allowing real-time adjustment of the wind turbine's active and reactive currents. This method, considering the influence of new energy output fluctuations and system power angle oscillations, determines a coordinated active and reactive power control scheme for the wind turbine that improves the voltage safety of the new energy grid connection point, avoiding potential voltage insecurity or continuous power angle oscillations that may occur with traditional constant voltage or constant power control of the wind turbine after fault clearance. Compared with the traditional method of reactive power withdrawal and active current constant rate ramp recovery control after low-voltage breakdown, the solution in this embodiment can effectively suppress voltage fluctuations after fault clearance, thereby improving the voltage safety of the new energy transmission system and suppressing repeated low-voltage breakdowns caused by voltage fluctuations. Attached Figure Description

[0046] The accompanying drawings, which are included to provide a further understanding of this specification and form part of it, do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 A flowchart of a collaborative control method for a new energy system in one embodiment of this specification is shown;

[0048] Figure 2 A flowchart of a collaborative control method for a new energy system according to an embodiment of this specification is shown;

[0049] Figure 3 A control strategy block diagram of a collaborative control method for a new energy system according to an embodiment of this specification is shown;

[0050] Figure 4 This specification shows a topology diagram of a wind and fire bundling and delivery system according to one embodiment;

[0051] Figure 5 This specification shows a diagram illustrating the active and reactive current output curves of the controlled new energy source in one embodiment.

[0052] Figure 6 This specification shows the active and reactive current output curves of the new energy source after control in one embodiment.

[0053] Figure 7 This specification shows a voltage curve diagram of the new energy generator before and after control in one embodiment;

[0054] Figure 8 A schematic diagram of a collaborative control device for a new energy system according to one embodiment of this specification is shown;

[0055] Figure 9 A schematic diagram of a computer device according to one embodiment of this specification is shown. Detailed Implementation

[0056] The principles and spirit of this specification will now be described with reference to several exemplary embodiments. It should be understood that these embodiments are given merely to enable those skilled in the art to better understand and implement this specification, and are not intended to limit the scope of this specification in any way. Rather, these embodiments are provided to make this disclosure more thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0057] Those skilled in the art will recognize that the embodiments described in this specification can be implemented as a system, apparatus, method, or computer program product. Therefore, the disclosure of this specification can be specifically implemented in the following forms: entirely hardware, entirely software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0058] Unlike conventional DC characteristics, new energy power generation equipment can provide reactive power support to the AC grid in addition to transmitting active power. To suppress voltage fluctuations, the active and reactive power control of wind turbines should be coordinated: on the one hand, providing reactive power support to the grid during voltage fluctuations after fault clearance; on the other hand, adjusting active power to improve the system's power angle stability, thereby ensuring the safety of the sending-end voltage. This is of great significance for further improving the limit of clean energy transmission.

[0059] Most transient control strategies for renewable energy units comprehensively consider the withstand capability of grid-connected converters and the reactive power support of the units to the system, aiming to improve the transient voltage stability of the system. Currently, there is no coordinated control strategy for renewable energy that comprehensively considers the transient power angle stability of the sending-end synchronous units and the voltage fluctuation problem at the renewable energy generator terminals. Considering that the short-circuit ratio is an important tool for measuring the grid strength of power electronic equipment grid-connected systems and analyzing system stability margins, comparing the system's operating short-circuit ratio with its critical short-circuit ratio can determine the system's operating state and assess the system's voltage support strength, helping to control the impact of renewable energy grid connection. However, currently, there is a lack of a short-circuit ratio index as a reference in renewable energy transient reactive power control strategies. Therefore, this specification's embodiments design active and reactive power control schemes for wind turbines after fault clearance. By comparing the sending-end system's operating short-circuit ratio with the boundary short-circuit ratio constrained by voltage safety, it determines how the control strategy should be switched, thereby improving the safety of the renewable energy sending-end voltage and suppressing repeated low-voltage breakdowns caused by voltage fluctuations. In this embodiment, the boundary short-circuit ratio can be derived with a voltage of 0.9pu as the operating boundary. When the operating short-circuit ratio of the system is lower than the boundary short-circuit ratio, it means that the voltage insecurity is relatively strong, and the control should prioritize reactive power support. When the operating short-circuit ratio is higher than the boundary short-circuit ratio, active power control should be prioritized to improve the system power angle stability and avoid the voltage of new energy grid connection from dropping due to the swing of the power angle of the sending end synchronous machine.

[0060] In this embodiment, 0.9pu is the per-unit voltage value, and the reference value is the rated value of the line voltage. Generally speaking, 0.9pu can be used as the safety constraint for steady-state voltage after a fault. Of course, other values ​​can also be set according to actual needs, in which case the derivation needs to be redone.

[0061] Based on this, the embodiments of this specification provide a collaborative control method for a new energy system. Figure 1 A flowchart of a collaborative control method for a new energy system according to an embodiment of this specification is shown. While this specification provides method operation steps or apparatus structures as illustrated in the following embodiments or figures, more or fewer operation steps or module units may be included in the method or apparatus based on conventional or non-inventive effort. In steps or structures where there is no logically necessary causal relationship, the execution order of these steps or the module structure of the apparatus is not limited to the execution order or module structure described in the embodiments and figures of this specification. When the method or module structure is applied in actual devices or terminal products, it can be executed sequentially or in parallel according to the method or module structure shown in the embodiments or figures (e.g., in a parallel processor or multi-threaded processing environment, or even a distributed processing environment).

[0062] Specifically, such as Figure 1 As shown, a collaborative control method for a new energy system provided in one embodiment of this specification may include the following steps:

[0063] Step S101: Obtain the system network parameters and operating parameters of the new energy system, the new energy output fluctuation parameters, and the system power angle oscillation parameters.

[0064] Step S102: Based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system, calculate the operating short-circuit ratio before the fault at the new energy grid connection point and the boundary short-circuit ratio under voltage safety constraints.

[0065] The method in this embodiment can be applied to computer equipment. It can acquire the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the system power angle oscillation parameters.

[0066] In one embodiment, the power output fluctuation parameters and system power angle oscillation parameters of the new energy system may include at least one of the following: the power angle, angular velocity, and angular acceleration signals of the sending-end synchronous generator relative to the receiving-end system of the new energy system, and the voltage and phase angle of the wind turbine grid connection point. In one embodiment, the system network parameters and operating parameters of the new energy system may include at least one of the following: the active power output before the wind turbine failure, the inertia of the sending-end synchronous generator, the rated capacity of the converter, the equivalent reactance of the sending-end synchronous generator from the new energy grid connection point, and the equivalent reactance of the sending-end and receiving-end synchronous generators from the new energy grid connection point.

[0067] The power angle, angular velocity, and angular acceleration signals of the sending-end synchronous generator relative to the receiving-end system, as well as the voltage and phase angle of the wind turbine grid connection point, can be detected in real time. This allows for the real-time acquisition of these signals. Subsequently, based on system network parameters and operating parameters, the operating short-circuit ratio before a fault at the renewable energy grid connection point and the boundary short-circuit ratio under voltage safety constraints can be calculated.

[0068] In some embodiments of this specification, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the system power angle oscillation parameters, the calculation of the operating short-circuit ratio before the fault at the grid connection point of the new energy and the boundary short-circuit ratio under voltage safety constraints may include calculating the operating short-circuit ratio and the boundary short-circuit ratio according to the following formulas:

[0069]

[0070]

[0071]

[0072]

[0073]

[0074] Where OSCR is the operating short-circuit ratio, CSCR is... _0.9 P is the boundary short-circuit ratio. s Before the wind turbine failed, it had active power output, x d x is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; l δ is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; δ is the power angle of the sending-end synchronous generator relative to the receiving-end system; θ is the phase angle of the voltage at the wind turbine grid connection point. In this embodiment, the boundary short-circuit ratio can be derived with a voltage of 0.9 as the operating boundary.

[0075] Step S103: In the case of clearing the fault in the new energy system, based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters, determine the active and reactive power coordinated control scheme of the wind turbine.

[0076] In the event of a fault clearing in a renewable energy system, a coordinated active and reactive power control scheme for the wind turbines can be determined based on the operating short-circuit ratio and the boundary short-circuit ratio. In one embodiment, the coordinated active and reactive power control scheme can be determined as either an active power priority scheme or a reactive power priority scheme, based on the magnitude of these ratios. This allows the wind turbines to provide reactive power support to the grid during voltage fluctuations after the fault is cleared, adjusting active power to improve system power angle stability and thus ensuring the safety of the sending-end voltage. Specifically, active power priority means that the converter prioritizes generating active power, and only after meeting active power demand does it generate reactive power based on remaining capacity. Reactive power priority means that only after meeting reactive power demand does it generate active power based on remaining capacity.

[0077] In the above embodiments, based on a comparison between the operating short-circuit ratio of the renewable energy grid-connected system and the boundary short-circuit ratio constrained by voltage safety, a control strategy prioritizing active power or reactive power is switched to. This allows for real-time adjustment of the active and reactive currents of the wind turbines. By considering the system network parameters and operating parameters, as well as the impact of renewable energy output fluctuations and system power angle oscillations, a coordinated active and reactive power control scheme for wind turbines that enhances voltage safety at the renewable energy grid connection point can be determined. This avoids the voltage insecurity or continuous power angle oscillations that may occur with traditional constant voltage or constant power control of wind turbines after fault clearance. Compared to traditional reactive power withdrawal and constant rate ramp recovery control of active current after low-voltage breakdown, the scheme in this embodiment effectively suppresses voltage fluctuations after fault clearance, thereby improving the voltage safety of the renewable energy sending-end system and suppressing repeated low-voltage breakdowns caused by voltage fluctuations.

[0078] In some embodiments of this specification, determining a wind turbine active and reactive power coordinated control scheme based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the renewable energy output fluctuation parameters and the system power angle oscillation parameters, may include: determining whether the operating short-circuit ratio is greater than the boundary short-circuit ratio; if the operating short-circuit ratio is greater than the boundary short-circuit ratio, determining the active power priority control scheme as the wind turbine active and reactive power coordinated control scheme; if the operating short-circuit ratio is not greater than the boundary short-circuit ratio, determining the reactive power priority control scheme as the wind turbine active and reactive power coordinated control scheme; wherein the active power priority control scheme and the reactive power priority control scheme are preset based on the renewable energy output fluctuation parameters and the system power angle oscillation parameters.

[0079] It can be determined whether the operating short-circuit ratio is greater than the boundary short-circuit ratio. If the operating short-circuit ratio is greater than the boundary short-circuit ratio, the active power priority control scheme is determined as the wind turbine active and reactive power coordinated control scheme. If the operating short-circuit ratio is not greater than the boundary short-circuit ratio, the reactive power priority control scheme is determined as the wind turbine active and reactive power coordinated control scheme. Active power priority means that the converter prioritizes generating active power, and only generates reactive power based on the remaining capacity after meeting the active power demand. Reactive power priority means that only generates active power based on the remaining capacity after meeting the reactive power demand. When the system's operating short-circuit ratio is lower than the boundary short-circuit ratio, it means that the voltage insecurity is relatively strong, and control should prioritize reactive power support; when the operating short-circuit ratio is higher than the boundary short-circuit ratio, active power control should be prioritized to improve the system's power angle stability and prevent the grid-connected voltage of new energy sources from dropping due to the swing of the power angle of the sending-end synchronous machine.

[0080] In some embodiments of this specification, the active power priority control scheme may include:

[0081] I pref =I p_original -MK1ω-a;

[0082]

[0083] Among them, I pref I is the reference value for the active current of the wind turbine. p_original The original active power control command (the original active power control command refers to the active current recovering at a constant rate ramp); ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator; M is the inertia of the sending-end synchronous generator; K1 is the adjustment parameter, taken as K1>0; I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3。

[0084] If the operating short-circuit ratio is greater than the critical short-circuit ratio, active power control strategy is implemented first, while reactive power control is limited, with the upper limit of reactive current amplitude being [value missing]. Among them, I N For the rated capacity of the converter, I pref This is the reference value for active current control. In this embodiment, the converter prioritizes generating active power, and then generates reactive power based on the remaining capacity after meeting the active power demand.

[0085] In some embodiments of this specification, the reactive power priority control scheme may include:

[0086] I qref =K2(1-V)I N ;

[0087]

[0088] Among them, I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3;I pref I is the reference value for the active current of the wind turbine. p_original The original power control command is ω, where ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator, M is the inertia of the sending-end synchronous generator, and K1 is the adjustment parameter, which is set to K1>0.

[0089] If the operating short-circuit ratio is less than the critical short-circuit ratio, reactive power control strategy is implemented first, while active power control is limited, with the upper limit of active current amplitude being [value missing]. Among them, I N For the rated capacity of the converter, I qref This is the reference value for reactive current control. In this embodiment, active power is generated based on the remaining capacity after meeting the reactive power demand.

[0090] In some embodiments of this specification, after determining the active and reactive power coordinated control scheme of the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters, the method may further include: executing the active and reactive power coordinated control scheme of the wind turbine to perform coordinated control; and ending the coordinated control when preset conditions are met.

[0091] In this embodiment, after determining the active and reactive power coordinated control scheme for the wind turbines, the scheme can be executed to coordinate the control of the system. The coordinated control ends when preset conditions are met. Through this method, the wind turbine output of the new energy system can be restored to the pre-fault level.

[0092] In some embodiments of this specification, the preset conditions may include at least one of the following: the voltage error is within a preset range; the control time exceeds a preset time limit.

[0093] In this embodiment, coordinated control can be terminated when the voltage error is within a preset range. A voltage error within the preset range means the voltage error is close to or equal to 0, i.e., it returns to the pre-fault level. In this embodiment, a maximum recovery time can also be set based on the active power recovery time requirements after a fault is cleared at the renewable energy power station, ensuring that the wind turbine output returns to the pre-fault level within a specified time. The preset time limit can be this maximum recovery time.

[0094] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. For details, please refer to the foregoing descriptions of the relevant processing embodiments; they will not be repeated here.

[0095] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0096] The above method will be described below with reference to a specific embodiment. However, it is worth noting that this specific embodiment is only for better illustration of this specification and does not constitute an improper limitation of this specification.

[0097] This specific embodiment provides a collaborative control method for a new energy system. To address the problem of repeated low-voltage breakdowns caused by voltage fluctuations after fault clearance in a new energy grid-connected system, the technical solution in this embodiment is: a collaborative active and reactive power control method to improve the voltage safety of the new energy grid-connected system. This method compares the operating short-circuit ratio of the new energy grid-connected system with the boundary short-circuit ratio constrained by voltage safety, and switches to an active power priority or reactive power priority control strategy to adjust the active and reactive currents of the wind turbines in real time. Please refer to [reference needed]. Figure 2 The flowchart illustrates a collaborative control method for a new energy system in a specific embodiment of this specification. For example... Figure 2 As shown, for the target wind power grid-connected system, the method disclosed in this specific embodiment includes the following:

[0098] Step 1: Design of active and reactive power control strategies.

[0099] 1) Active power control strategy

[0100] A wind turbine active current supplementary controller is designed based on the Lyapunov direct method, which is superimposed on the original active current output command. The controller design is as follows:

[0101] u = -MK1ω - a;

[0102] In the formula, u is the change in active power output of the wind turbine; ω is the angular velocity of the sending-end synchronous generator relative to the receiving end; a is the angular acceleration of the sending-end synchronous generator; M is the inertia of the sending-end synchronous generator; K1 is the adjustment parameter, and K1>0 is taken.

[0103] In this embodiment, the designed active power controller is an additional correction command on the original active power curve. When the system power angle stabilizes, the output of the active power controller is zero, which can maximize the integrity of the original control.

[0104] Under the control of this controller, the reference value of the active current of the wind turbine is:

[0105] I pref =I p_original +u;

[0106] In the formula, I p_original This refers to the original power control command.

[0107] 2) Reactive power control strategy

[0108] For constant voltage control, the reactive current reference value is:

[0109] I qref =K2(1-V)I N ;

[0110] In the formula, V is the voltage at the grid connection point of the new energy source, taken as a per-unit value; I N K2 is the rated capacity of the converter, taken as a per-unit value; K2 is the adjustment parameter, taken as 1. <K2<3。

[0111] Step 2: Signal measurement.

[0112] The module for feeding back the relative power angle, frequency, and acceleration signals of the synchronous generator consists of a measurement stage, a transmission stage, and a differential calculation stage; the module for feeding back the grid-connected voltage of the wind turbine consists of a measurement stage and a transmission stage. Please refer to [reference needed]. Figure 3 The diagram shows the control strategy block diagram of the collaborative control method for the new energy system in this embodiment. Figure 3 In this context, ω0 is the initial angular velocity, V0 is the initial voltage at the wind turbine's grid connection point, a is the angular acceleration, and I... pref I is the reference value for the active current of the wind turbine. qref This is the reference value for reactive current.

[0113] 1) Measurement process

[0114] The angular velocity of the synchronizing units at the sending and receiving ends is measured, and the dynamics are measured using a first-order lag element. It means that T mea The time constant is used for measurement. In this embodiment, the transient active power output of the wind turbine is controlled by measuring the angular velocity of the nearby synchronous machine, rather than the network frequency. Unlike the network frequency at any location during steady state, which can always effectively characterize the rotational speed dynamics of the synchronous machine, only the angular velocity near the synchronous machine during transient state can more effectively characterize the rotational speed dynamics of the nearby synchronous machine. Therefore, the measurement location of the relevant network frequency must be close to the representative synchronous machines in the critical group and the remaining group to make the results more accurate.

[0115] 2) Transmission stage

[0116] Transmission dynamics using a first-order lag element It means that T tran Let s be the time constant of the transmission link, and s be a complex variable. When the real part is zero and the imaginary part is the angular velocity, it is the frequency response.

[0117] 3) Differential calculation stage

[0118] Differential dynamics is represented as T div is the time constant of the differential calculation process.

[0119] Step 3: Calculate and compare the size of OSCR with that of CSCR_0.9.

[0120] The formula for calculating the OSCR (Operating Short-Circuit Ratio) at the wind turbine's grid connection point before the fault is:

[0121]

[0122]

[0123] Among them, P s The wind turbine had active power output before the failure; x d The equivalent reactance (pu) of the sending-end synchronous machine from the renewable energy grid connection point; x l The equivalent reactance (pu) between the transmitting and receiving end synchronous machine and the new energy grid connection point.

[0124] The formula for calculating the boundary short-circuit ratio CSCR_0.9 under voltage safety constraints is as follows:

[0125]

[0126]

[0127]

[0128] In the formula, δ is the power angle of the sending-end synchronous generator relative to the receiving-end system; θ is the phase angle of the voltage at the wind turbine grid connection point.

[0129] Step 4: Coordinated Control of Active and Reactive Power of Wind Turbines

[0130] The OSCR and CSCR_0.9 are calculated from step 3. The active and reactive power coordinated control scheme for the wind turbine after fault clearance is designed as follows:

[0131] OSCR>CSCR _0.9 :

[0132] OSCR <CSCR _0.9 :

[0133] If the operating short-circuit ratio is greater than the critical short-circuit ratio, active power control strategy is implemented first, while reactive power control is limited, with the upper limit of reactive current amplitude being [value missing]. Among them, I N For the rated capacity of the converter, I pref This is the reference value for active current control; if the operating short-circuit ratio is less than the critical short-circuit ratio, then reactive power control strategy is prioritized, and active power control is limited, with the upper limit of the active current amplitude being [value missing]. Among them, I N For the rated capacity of the converter, I qref This is the reference value for reactive current control.

[0134] Based on the active power recovery time requirements after a fault is cleared at a renewable energy power station, a maximum recovery time is set to ensure that the wind turbine output recovers to the pre-fault level within the specified time. Control is deactivated if the control duration exceeds the time limit specified for the renewable energy power station.

[0135] The voltage safety of the new energy sending end is improved after fault clearance by simultaneously controlling the active and reactive power of the wind turbine. The control strategy switching is based on the magnitude of the operating short-circuit ratio and the critical short-circuit ratio of the new energy power station: if the operating short-circuit ratio is greater than the critical short-circuit ratio, the active power control strategy is implemented first, and the reactive power control is limited; if the operating short-circuit ratio is less than the critical short-circuit ratio, the reactive power control strategy is implemented first, and the active power control is limited.

[0136] Compared with the prior art, the method in this specific embodiment has the following advantages: it can determine the active and reactive power coordinated control scheme of wind turbines to improve the voltage safety of the new energy grid connection point based on the system network parameters and operating parameters, taking into account the influence of new energy power output fluctuations and system power angle oscillations. This avoids the voltage insecurity or continuous power angle oscillation that may occur in the constant voltage or constant power control of wind turbines after the traditional fault is cleared, and can improve the voltage safety of the new energy grid connection system.

[0137] To verify the correctness of the above analysis, a simulation platform was built as follows: Figure 4 The model of the new energy source plus synchronous generator combined power transmission system shown was simulated and verified according to the following parameters.

[0138] The direct-drive wind turbine has a capacity of 500 MVA and an actual output of 250 MW; the sending-end synchronous generator has an active power output of 300 MW; the receiving end is an infinite power grid. Measurement time constant: T mea =0.02s, T tran =0.02s, T div =0.003s; Controller adjustment parameters: K1=1, K2=1.

[0139] At 0.5s, a three-phase permanent short circuit occurred on one of the circuits of the double-circuit line, and the fault was cleared 0.1s later.

[0140] If a scheme is adopted where the reactive power of the wind turbine is immediately withdrawn after the fault is cleared and the active current recovers at a constant rate with a ramp-down approach, a simulation analysis is performed for the case where the recovery rate is 100% / s. This is compared with the changes in active and reactive power output of the new energy source under the collaborative control method in this specific embodiment. Figure 5 and Figure 6 As shown, the control effect is compared to... Figure 7 As shown. By Figure 7 It can be seen that, compared with the traditional method of reactive power withdrawal and active current constant rate ramp recovery control after low-voltage shutdown, the method in this specific embodiment can effectively suppress voltage fluctuations after fault clearance, thereby improving the voltage safety of the new energy transmission system and the voltage safety of the new energy grid-connected system.

[0141] Based on the same inventive concept, this specification also provides a collaborative control device for a new energy system, as described in the following embodiments. Since the principle of the collaborative control device for a new energy system is similar to that of the collaborative control method for a new energy system, the implementation of the collaborative control device can refer to the implementation of the collaborative control method for a new energy system, and repeated details will not be elaborated further. As used below, the terms "unit" or "module" can refer to a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated. Figure 8 This is a structural block diagram of a collaborative control device for a new energy system, as described in the embodiments of this specification. Figure 8 As shown, it includes: an acquisition module 801, a calculation module 802, and a determination module 803. The structure is described below.

[0142] The acquisition module 801 is used to acquire the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system.

[0143] The calculation module 802 is used to calculate the operating short-circuit ratio before the fault at the grid connection point of the new energy source and the boundary short-circuit ratio under voltage safety constraints, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy source and the system power angle oscillation parameters.

[0144] The determination module 803 is used to determine the active and reactive power coordinated control scheme of the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the power output fluctuation parameters of the new energy system and the power angle oscillation parameters, when the fault of the new energy system is cleared.

[0145] In some embodiments of this specification, the calculation module may be specifically used to calculate the running short-circuit ratio and the boundary short-circuit ratio according to the following formulas:

[0146]

[0147]

[0148]

[0149]

[0150]

[0151] Where OSCR is the operating short-circuit ratio, CSCR is... _0.9 P is the boundary short-circuit ratio. s Before the wind turbine failed, it had active power output, x d x is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; l δ is the equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; δ is the power angle of the sending-end synchronous generator relative to the receiving-end system; θ is the phase angle of the voltage at the wind turbine grid connection point.

[0152] In some embodiments of this specification, the determining module may be specifically used for:

[0153] Determine whether the operating short-circuit ratio is greater than the boundary short-circuit ratio;

[0154] If it is determined that the operating short-circuit ratio is greater than the boundary short-circuit ratio, the active power priority control scheme is determined to be the wind turbine active power and reactive power coordinated control scheme.

[0155] If it is determined that the operating short-circuit ratio is not greater than the boundary short-circuit ratio, the reactive power priority control scheme is determined as the wind turbine active and reactive power coordinated control scheme.

[0156] In some embodiments of this specification, the active power priority control scheme may include:

[0157] I pref =I p_original-MK1ω-a;

[0158]

[0159] Among them, I pref I is the reference value for the active current of the wind turbine. p_original The original power control command is ω, where ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator, M is the inertia of the sending-end synchronous generator, and K1 is the adjustment parameter, which is set to K1>0.

[0160] I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3。

[0161] In some embodiments of this specification, the reactive power priority control scheme may include:

[0162] I qref =K2(1-V)I N ;

[0163]

[0164] Among them, I qref V is the reactive current reference value; I is the voltage at the new energy grid connection point; N K1 is the rated capacity of the converter; K2 is the adjustment parameter, which is set to 1. <K2<3;

[0165] I pref I is the reference value for the active current of the wind turbine. p_original The original power control command is ω, where ω is the angular velocity of the sending-end synchronous generator relative to the receiving end, a is the angular acceleration of the sending-end synchronous generator, M is the inertia of the sending-end synchronous generator, and K1 is the adjustment parameter, which is set to K1>0.

[0166] In some embodiments of this specification, the device may further include a control module, which may be specifically used to: execute the active and reactive power coordinated control scheme of the wind turbine and perform coordinated control; and terminate the coordinated control when preset conditions are met.

[0167] In some embodiments of this specification, the preset conditions may include at least one of the following: the voltage error is within a preset range; the control time exceeds a preset time limit.

[0168] As can be seen from the above description, the embodiments of this specification achieve the following technical effects: based on the comparison between the operating short-circuit ratio of the new energy grid-connected system and the boundary short-circuit ratio constrained by voltage safety, the control strategy is switched to active power priority or reactive power priority, and the active and reactive currents of the wind turbine are adjusted in real time. Compared with the traditional control of reactive power withdrawal and constant rate ramp recovery of active current after low-voltage breakdown, the scheme in this embodiment can effectively suppress voltage fluctuations after fault clearance, thereby improving the voltage safety of the new energy sending-end system and suppressing repeated low-voltage breakdowns caused by voltage fluctuations.

[0169] This specification also provides a computer device, which can be found in the following description. Figure 9 The diagram shown illustrates the computer device structure for the collaborative control method of the new energy system provided in the embodiments of this specification. Specifically, the computer device may include an input device 91, a processor 92, and a memory 93. The memory 93 stores processor-executable instructions. When the processor 92 executes the instructions, it implements the steps of the collaborative control method of the new energy system described in any of the above embodiments.

[0170] In this embodiment, the input device can specifically be one of the main devices for information exchange between the user and the computer system. The input device may include a keyboard, mouse, camera, scanner, light pen, handwriting input tablet, voice input device, etc.; the input device is used to input raw data and programs for processing these data into the computer. The input device can also receive data transmitted from other modules, units, and devices. The processor can be implemented in any suitable manner. For example, the processor can take the form of a microprocessor or processor and a computer-readable medium storing computer-readable program code (e.g., software or firmware) executable by the (micro)processor, logic gates, switches, application-specific integrated circuits (ASICs), programmable logic controllers, and embedded microcontrollers, etc. The memory can specifically be a memory device used to store information in modern information technology. The memory can include multiple layers; in digital systems, anything that can store binary data can be considered memory; in integrated circuits, a circuit without physical form but with storage function is also called memory, such as RAM, FIFO, etc.; in a system, a storage device with physical form is also called memory, such as a memory stick, TF card, etc.

[0171] In this embodiment, the specific functions and effects implemented by the computer device can be explained in comparison with other embodiments, and will not be repeated here.

[0172] This specification also provides a computer storage medium for a collaborative control method based on a new energy system, wherein the computer storage medium stores computer program instructions that, when executed, implement the steps of the collaborative control method for the new energy system described in any of the above embodiments.

[0173] In this embodiment, the storage medium includes, but is not limited to, Random Access Memory (RAM), Read-Only Memory (ROM), cache, hard disk drive (HDD), or memory card. The memory can be used to store computer program instructions. The network communication unit can be an interface configured according to standards specified in the communication protocol for network connection communication.

[0174] In this embodiment, the specific functions and effects implemented by the program instructions stored in the computer storage medium can be explained by comparison with other embodiments, and will not be repeated here.

[0175] Obviously, those skilled in the art will understand that the modules or steps of the embodiments described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using computer-executable program code, thereby storing them in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those presented herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the embodiments of this specification are not limited to any particular combination of hardware and software.

[0176] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this specification should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents.

[0177] The above description is merely a preferred embodiment of this specification and is not intended to limit this specification. Various modifications and variations can be made to the embodiments described herein by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of protection of this specification.

Claims

1. A collaborative control method for a new energy system, characterized in that, include: Obtain the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system; Based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system and the power angle oscillation parameters of the system, the operating short-circuit ratio before the fault at the grid connection point of the new energy and the boundary short-circuit ratio under voltage safety constraints are calculated. In the event that the fault in the new energy system has been cleared, the active and reactive power coordinated control scheme of the wind turbine is determined based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters. Specifically, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the system power angle oscillation parameters, the operating short-circuit ratio before the fault at the new energy grid connection point and the boundary short-circuit ratio under voltage safety constraints are calculated, including: Calculate the operating short-circuit ratio and the boundary short-circuit ratio using the following formulas: ; ; ; ; ; in, To achieve the operating short-circuit ratio, For boundary short-circuit ratio, The wind turbine was still generating power before the failure. The equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; The equivalent reactance between the transmitting and receiving end synchronous machines and the new energy grid connection point; The power angle of the sending-end synchronous generator relative to the receiving-end system; The phase angle of the voltage at the wind turbine's grid connection point; The active and reactive power coordinated control scheme for wind turbines is determined based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the renewable energy output fluctuation parameters and the system power angle oscillation parameters. This scheme includes: Determine whether the operating short-circuit ratio is greater than the boundary short-circuit ratio; If it is determined that the operating short-circuit ratio is greater than the boundary short-circuit ratio, the active power priority control scheme is determined to be the wind turbine active power and reactive power coordinated control scheme. If it is determined that the operating short-circuit ratio is not greater than the boundary short-circuit ratio, the reactive power priority control scheme is determined as the wind turbine active and reactive power coordinated control scheme. The active power priority control scheme and the reactive power priority control scheme are pre-set based on the power output fluctuation parameters of the new energy source and the power angle oscillation parameters of the system.

2. The collaborative control method for a new energy system according to claim 1, characterized in that, The active power priority control scheme includes: in, This is a reference value for the active current of the wind turbine. The original power control command, The angular velocity of the sending-end synchronous generator relative to the receiving end is... The angular acceleration of the sending-end synchronous generator; The inertia of the sending-end synchronous generator; To adjust the parameters, take ; This is a reference value for reactive current. Voltage at the grid connection point for new energy sources; This refers to the rated capacity of the converter; To adjust the parameters, take .

3. The collaborative control method for a new energy system according to claim 1, characterized in that, The reactive power priority control scheme includes: in, This is a reference value for reactive current. Voltage at the grid connection point for new energy sources; This refers to the rated capacity of the converter; To adjust the parameters, take ; This is a reference value for the active current of the wind turbine. The original power control command, The angular velocity of the sending-end synchronous generator relative to the receiving end is... The angular acceleration of the sending-end synchronous generator; The inertia of the sending-end synchronous generator; To adjust the parameters, take .

4. The collaborative control method for a new energy system according to claim 1, characterized in that, After determining the active and reactive power coordinated control scheme for the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the new energy output fluctuation parameters and the system power angle oscillation parameters, the following is also included: The aforementioned active and reactive power coordinated control scheme for the wind turbine is executed to perform coordinated control. The collaborative control ends when the preset conditions are met.

5. The collaborative control method for a new energy system according to claim 4, characterized in that, The preset conditions include at least one of the following: The voltage error is within the preset range; The control time exceeds the preset time limit.

6. A collaborative control device for a new energy system, characterized in that, include: The acquisition module is used to acquire the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system, and the power angle oscillation parameters of the system. The calculation module is used to calculate the operating short-circuit ratio before the fault at the grid connection point of the new energy system and the boundary short-circuit ratio under voltage safety constraints, based on the system network parameters and operating parameters of the new energy system, the power output fluctuation parameters of the new energy system and the system power angle oscillation parameters. The determination module is used to determine the active and reactive power coordinated control scheme of the wind turbine based on the operating short-circuit ratio and the boundary short-circuit ratio, combined with the power output fluctuation parameters of the new energy system and the power angle oscillation parameters, when the fault of the new energy system is cleared. Specifically, the calculation module is used to calculate the running short-circuit ratio and the boundary short-circuit ratio according to the following formulas: ; ; ; ; ; in, To achieve the operating short-circuit ratio, For boundary short-circuit ratio, The wind turbine was still generating power before the failure. The equivalent reactance of the sending-end synchronous generator from the renewable energy grid connection point; The equivalent reactance between the transmitting and receiving end synchronous machines and the new energy grid connection point; The power angle of the sending-end synchronous generator relative to the receiving-end system; The phase angle of the voltage at the wind turbine's grid connection point; Specifically, the determining module is used to: determine whether the operating short-circuit ratio is greater than the boundary short-circuit ratio; if the operating short-circuit ratio is greater than the boundary short-circuit ratio, determine the active power priority control scheme as the wind turbine active and reactive power coordinated control scheme; if the operating short-circuit ratio is not greater than the boundary short-circuit ratio, determine the reactive power priority control scheme as the wind turbine active and reactive power coordinated control scheme; wherein the active power priority control scheme and the reactive power priority control scheme are preset based on the new energy output fluctuation parameters and the system power angle oscillation parameters.

7. A computer device, characterized in that, It includes a processor and a memory for storing processor-executable instructions, wherein the processor, when executing the instructions, implements the steps of the method according to any one of claims 1 to 5.

8. A computer-readable storage medium storing computer instructions thereon, characterized in that, When the instructions are executed by the processor, they implement the steps of the method according to any one of claims 1 to 5.

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