Cooperative control method and device for direct-current power transmission system and compressed air energy storage system

Abstract

The invention relates to the technical field of power systems, in particular to a cooperative control method and device for a direct-current power transmission system and a compressed air energy storage system, and the method comprises the steps: obtaining a current operation state and a current commutation state of a power grid; if the current operation state is a preset abnormal state or the current commutation state is a commutation failure state, obtaining a bus voltage deviation of an inversion side of the direct current power transmission system; and cooperatively controlling the compressed air energy storage system and the direct-current power transmission system based on the bus voltage deviation. Therefore, the problem that the operation stability and safety of a power system are affected due to the fact that the power grid is abnormal or commutation fails is solved.

Description

Technical Field

[0001] The present application relates to the technical field of power systems, and in particular to a method and device for coordinated control of a direct current transmission system and a compressed air energy storage system. Background Art

[0002] In traditional DC feed-in systems, bus failures at the receiving end (inverter side) often lead to commutation failures in the DC system, which seriously affects the stability and safe operation of the system. Commutation failure is a common technical problem in DC transmission systems. It is mainly caused by the insufficient inverter shutdown angle of the converter station in the DC system, which causes the inverter to fail to switch successfully at the voltage trough, thus causing a short circuit or voltage drop.

[0003] Existing solutions, such as static VAR compensators or static synchronous compensators, can provide necessary reactive power support and suppress voltage fluctuations to a certain extent, but these traditional methods have limitations in voltage recovery and system dynamic response, especially in large-scale or complex power grid environments, and their effects are often not very ideal. In addition, the high cost and complex maintenance requirements of these devices also increase the operational burden of the power grid. Summary of the invention

[0004] The present application provides a method and device for collaborative control of a direct current transmission system and a compressed air energy storage system to solve problems such as the stability and safety of power system operation affected by abnormalities in the power grid or commutation failures.

[0005] A first aspect embodiment of the present application provides a method for collaboratively controlling a DC transmission system and a compressed air energy storage system, comprising the following steps: obtaining a current operating state and a current commutation state of a power grid; if the current operating state is a preset abnormal state or the current commutation state is a commutation failure state, obtaining a bus voltage deviation on the inverter side of the DC transmission system; and collaboratively controlling the compressed air energy storage system and the DC transmission system based on the bus voltage deviation.

[0006] Optionally, the compressed air energy storage system and the direct current transmission system are collaboratively controlled based on the bus voltage deviation, including: using a wavelet packet function to decompose the bus voltage deviation into a first component and a second component in the frequency domain, the frequency of the first component being lower than the frequency of the second component; controlling the compressed air energy storage system to respond to the first component; and controlling the direct current transmission system to respond to the second component.

[0007] Optionally, controlling the compressed air energy storage system to respond to the first component includes: obtaining the required reactive power of the power grid; adjusting the excitation reference voltage of the generator in the compressed air energy storage system so that the reactive power output currently output by the power grid is adjusted to the required reactive power, wherein the excitation reference voltage is related to the excitation current, and the reactive power is related to the excitation reference voltage.

[0008] Optionally, the relationship between the excitation reference voltage and the excitation current is:

[0009] I f = k·(U f -U L );

[0010] Among them, I f is the excitation current, k is the gain of the excitation system, U f is the excitation reference voltage, U L is the saturation voltage of the generator;

[0011] The relationship between reactive power and excitation current is:

[0012]

[0013] Where Q is reactive power, V t is the generator terminal voltage, I f is the excitation current, is the power factor angle.

[0014] Optionally, controlling the DC transmission system to respond to the second component includes: obtaining a current bus voltage on the inverter side of the DC transmission system, a maximum value of an inverter trigger angle, and a first DC current command value of a low-voltage current limiting controller; calculating a second DC current command value based on the current bus voltage and the maximum value; selecting a minimum value between the first DC current command value and the second DC current command value as a final DC current command value; and adjusting the DC current of the DC transmission system based on the final DC current command value.

[0015] Optionally, before adjusting the DC current of the DC transmission system based on the final DC current command value, it also includes: obtaining a trigger lead angle output by a constant current controller on the inverter side and a trigger lead angle output by a fixed turn-off angle control on the inverter side; if the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed turn-off angle control on the inverter side, adjusting the DC current of the DC transmission system based on the final DC current command value.

[0016] Optionally, after decomposing the bus voltage deviation into the first component and the second component in the frequency domain using the wavelet packet function, it also includes: judging whether the compressed air energy storage system satisfies a first preset constraint; if the first preset constraint is satisfied, the quantity ratio of the first component and the second component is not adjusted, otherwise the quantity of the first component is reduced; judging whether the direct current transmission system satisfies a second preset constraint; if the second preset constraint is satisfied, the quantity ratio of the first component and the second component is not adjusted, otherwise judging whether there is additional reactive power in the compressed air energy storage system; if there is additional reactive power, reducing the quantity of the second component and transferring the reduced second component to the compressed air energy storage system.

[0017] The second aspect of the present application provides a collaborative control device for a DC transmission system and a compressed air energy storage system, including: a first acquisition module, used to acquire the current operating state and the current commutation state of the power grid; a second acquisition module, used to acquire the bus voltage deviation on the inverter side of the DC transmission system if the current operating state is a preset abnormal state or the current commutation state is a commutation failure state; and a control module, used to collaboratively control the compressed air energy storage system and the DC transmission system based on the bus voltage deviation.

[0018] Optionally, the control module is further used to: decompose the bus voltage deviation into a first component and a second component in the frequency domain using a wavelet packet function, the frequency of the first component being lower than the frequency of the second component; control the compressed air energy storage system to respond to the first component; and control the direct current transmission system to respond to the second component.

[0019] Optionally, the control module is further used to: obtain the required reactive power of the power grid; adjust the excitation reference voltage of the generator in the compressed air energy storage system so that the reactive power output currently output by the power grid is adjusted to the required reactive power, wherein the excitation reference voltage is related to the excitation current, and the reactive power is related to the excitation reference voltage.

[0020] Optionally, the relationship between the excitation reference voltage and the excitation current is:

[0021] I f = k·(U f -U L );

[0022] Among them, I f is the excitation current, k is the gain of the excitation system, U f is the excitation reference voltage, U L is the saturation voltage of the generator;

[0023] The relationship between reactive power and excitation current is:

[0024]

[0025] Where Q is reactive power, V t is the generator terminal voltage, I f is the excitation current, is the power factor angle.

[0026] Optionally, the control module is further used to: obtain the current bus voltage on the inverter side of the DC transmission system, the maximum value of the inverter trigger angle and the first DC current command value of the low-voltage current limiting controller; calculate the second DC current command value based on the current bus voltage and the maximum value; select the minimum value of the first DC current command value and the second DC current command value as the final DC current command value; and adjust the DC current of the DC transmission system based on the final DC current command value.

[0027] Optionally, it also includes: an adjustment module, which is used to obtain the trigger lead angle output by the constant current controller on the inverter side and the trigger lead angle output by the fixed shutdown angle control on the inverter side before adjusting the DC current of the DC transmission system based on the final DC current command value; if the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed shutdown angle control on the inverter side, the DC current of the DC transmission system is adjusted based on the final DC current command value.

[0028] Optionally, it also includes: a judgment module, which is used to judge whether the compressed air energy storage system meets the first preset constraint condition after decomposing the bus voltage deviation into the first component and the second component in the frequency domain using the wavelet packet function; if the first preset constraint condition is met, the quantity ratio of the first component and the second component is not adjusted, otherwise the quantity of the first component is reduced; judge whether the direct current transmission system meets the second preset constraint condition; if the second preset constraint condition is met, the quantity ratio of the first component and the second component is not adjusted, otherwise it is judged whether there is additional reactive power in the compressed air energy storage system; if there is additional reactive power, the quantity of the second component is reduced, and the reduced second component is transferred to the compressed air energy storage system.

[0029] A third aspect of the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to execute a method for coordinated control of a DC power transmission system and a compressed air energy storage system as described in the above embodiment.

[0030] The fourth aspect of the present application provides a computer-readable storage medium having a computer program or instruction stored thereon, and the computer program or instruction is executed by a processor to perform a method for coordinated control of a direct current transmission system and a compressed air energy storage system.

[0031] Therefore, this application has at least the following beneficial effects:

[0032] The embodiment of the present application can coordinately control the compressed air energy storage system and the DC power transmission system based on the bus voltage deviation on the inverter side of the DC power transmission system when the power grid is in an abnormal operating state or the commutation fails, and utilize the respective characteristics of the DC power transmission system and the compressed air energy storage system to achieve complementary advantages of the two systems in terms of voltage support, effectively improve the problem of bus voltage fluctuation on the inverter side, thereby suppressing commutation failure, and further improving the stability, safety and reliability of the power system operation. Thus, the technical problems such as the stability and safety of the power system operation affected by abnormal power grid or commutation failure are solved.

[0033] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0035] Figure 1 A flowchart of a method for coordinated control of a DC power transmission system and a compressed air energy storage system according to an embodiment of the present application;

[0036] Figure 2 A system structure diagram of coordinated control of a DC power transmission system and a compressed air energy storage system provided according to an embodiment of the present application;

[0037] Figure 3 A flowchart of a method for coordinated control of a DC power transmission system and a compressed air energy storage system according to an embodiment of the present application;

[0038] Figure 4 A schematic diagram of a coordinated control device for a direct current power transmission system and a compressed air energy storage system provided according to an embodiment of the present application;

[0039] Figure 5 It is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present application. DETAILED DESCRIPTION

[0040] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0041] The following describes the method and device for collaborative control of a DC power transmission system and a compressed air energy storage system in an embodiment of the present application with reference to the accompanying drawings. In view of the problem mentioned in the background technology center that the DC system's commutation failure or abnormal operation of the power grid often results from a receiving-end bus failure, which seriously affects the stability and safe operation of the system, the present application provides a method for collaborative control of a DC power transmission system and a compressed air energy storage system. In this method, when the power grid is in an abnormal operating state or the commutation fails, the compressed air energy storage system and the DC power transmission system can be collaboratively controlled based on the bus voltage deviation on the inverter side of the DC power transmission system, and the respective characteristics of the DC power transmission system and the compressed air energy storage system are utilized to achieve complementary advantages of the two systems in terms of voltage support. As a result, the stability and safety of the power system operation caused by abnormalities in the power grid or commutation failures are solved.

[0042] Specifically, Figure 1 A schematic flow chart of a method for coordinated control of a direct current transmission system and a compressed air energy storage system provided in an embodiment of the present application.

[0043] like Figure 1 As shown, the coordinated control method of the DC power transmission system and the compressed air energy storage system includes the following steps:

[0044] In step S101, the current operation state and current commutation state of the power grid are obtained.

[0045] Commutation refers to the process of transferring current from one converter valve to another in a DC transmission system. In a DC transmission system, a converter station is used to convert AC power into DC power (rectification process) or convert DC power back into AC power (inversion process).

[0046] In step S102, if the current operating state is a preset abnormal state or the current commutation state is a commutation failure state, the bus voltage deviation on the inverter side of the direct current transmission system is obtained.

[0047] Among them, the preset abnormal state can be local voltage fluctuation, low-frequency oscillation, bus voltage fluctuation at the receiving end (inverter side) and the like.

[0048] It should be noted that during the inversion process, if the inverter's shutdown angle is insufficient, the current may not be able to smoothly transfer from one converter valve to the next, which is called commutation failure. Commutation failure is a common technical problem in DC transmission systems. It mainly occurs in inverter stations and is usually caused by insufficient inverter shutdown angles. When commutation failure occurs, the inverter cannot successfully switch at the voltage trough, which causes the current to continue to flow through the converter valve that is about to be shut down instead of transferring to the next converter valve, causing a short circuit or voltage drop.

[0049] It can be understood that, in the embodiment of the present application, when the current grid operation state is a preset abnormal state or the current commutation state is a commutation failure, the bus voltage deviation on the inverter side of the DC transmission system is obtained, so as to subsequently control the compressed air energy storage system and the DC transmission system based on the bus voltage deviation.

[0050] In step S103, the compressed air energy storage system and the direct current transmission system are cooperatively controlled based on the bus voltage deviation.

[0051] It can be understood that the embodiments of the present application can coordinately control the compressed air energy storage system and the DC transmission system based on the bus voltage deviation on the inverter side of the DC transmission system, improve the bus voltage fluctuation at the receiving end, and thus suppress commutation failure.

[0052] In an embodiment of the present application, a compressed air energy storage system and a direct current transmission system are collaboratively controlled based on a bus voltage deviation, including: using a wavelet packet function to decompose the bus voltage deviation into a first component and a second component in the frequency domain, the frequency of the first component being lower than the frequency of the second component; controlling the compressed air energy storage system to respond to the first component; and controlling the direct current transmission system to respond to the second component.

[0053] The wavelet packet function is wavelet packet decomposition. Wavelet packet decomposition refers to a signal decomposition technique that can decompose a signal into components in multiple frequency bands. The first component can be a low-frequency component, and the second component can be a high-frequency component. The frequency of the first component is lower than the frequency of the second component.

[0054] It can be understood that the embodiments of the present application can use a preset wavelet function to decompose the bus voltage deviation, decompose the bus voltage deviation into a first component and a second component in the frequency domain, so that the compressed air energy storage system responds to the first component and the DC transmission system responds to the second component, so as to achieve complementary matching between the two systems, so as to achieve rapid response of high-frequency signals by the DC transmission control system and persistent response of low-frequency signals by the compressed air energy storage system, so as to give full play to the rapid response capability of the DC transmission system and the persistence of the output of the compressed air energy storage system.

[0055] In an embodiment of the present application, after decomposing the bus voltage deviation into a first component and a second component in the frequency domain using a wavelet packet function, it also includes: judging whether the compressed air energy storage system satisfies a first preset constraint; if the first preset constraint is satisfied, the quantitative ratio of the first component and the second component is not adjusted, otherwise the quantity of the first component is reduced; judging whether the direct current transmission system satisfies a second preset constraint; if the second preset constraint is satisfied, the quantitative ratio of the first component and the second component is not adjusted, otherwise judging whether there is additional reactive power in the compressed air energy storage system; if there is additional reactive power, reducing the quantity of the second component and transferring the reduced second component to the compressed air energy storage system.

[0056] The first preset constraint condition is a constraint satisfying the following formula, and the second preset constraint is a control margin constraint, and the formula is:

[0057]

[0058] in, is the lower limit of the compressed air energy storage output power at time t, is the upper limit of the compressed air energy storage output power at time t.

[0059] It can be understood that the embodiment of the present application first determines whether the compressed air energy storage system satisfies the first preset constraint condition. If so, the ratio of the first component to the second component is not adjusted; if not, the quantity of the first component is reduced. Secondly, it is determined whether the DC power transmission system satisfies the second preset constraint condition. If so, the quantity ratio of the first component to the second component is not adjusted; otherwise, it is determined whether the compressed air energy storage system has additional reactive power; if so, the quantity of the second component is reduced and the reduced second component is transferred to the compressed air energy storage system.

[0060] Specifically, the specific steps of dividing the first component and the second component in the embodiment of the present application are as follows:

[0061] First, using wavelet signal as filter, the DC feed-in receiving end bus voltage signal (inverter side bus voltage deviation) is decomposed in time domain and frequency domain into a series of signal components with the same bandwidth and different center frequencies. According to the different response time scales of the DC transmission control system and the compressed air energy storage system participating in the bus voltage regulation, the pressure difference command is decomposed into two high and low segments, where the number of nodes in each frequency band corresponds to the response time of the compressed air energy storage system, so that the low-frequency component corresponding to the compressed air energy storage system is equal to the resolution of wavelet packet decomposition, that is, there is only one node in the low-frequency band. The number of nodes in the high-frequency band is determined by the response time of the DC transmission control system.

[0062] Secondly, considering the regulation margin of the DC transmission control system and the dynamic response characteristics of the compressed air energy storage system, a coordinated sliding translation strategy is proposed.

[0063] 1. Determine whether the output of the compressed air energy storage system meets the constraints of the following formula. If the constraints are met, no adjustment will be made.

[0064]

[0065] in, is the lower limit of the energy storage output power at time t, is the upper limit of the energy storage output power at time t.

[0066] If it is not satisfied, the adjustment strategy of the compressed air energy storage system is to gradually reduce the low-frequency component from large to small, and at the same time, the DC transmission control system temporarily expands the control range;

[0067] 2. Determine whether the DC transmission control system meets the control margin constraint. If it does, no adjustment will be made. If not, the DC transmission control system adjustment strategy is: determine whether the compressed air energy storage system has a surplus output. If so, gradually reduce the number of high-frequency components from small to large, and the discarded components will be borne by the compressed air energy storage, giving full play to the characteristics of the compressed air energy storage system with a wide adjustment range.

[0068] Finally, a communication network is established between the compressed air energy storage system and the DC transmission system to achieve real-time data exchange and control signal synchronization.

[0069] In an embodiment of the present application, controlling the compressed air energy storage system to respond to the first component includes: obtaining the required reactive power of the power grid; adjusting the excitation reference voltage of the generator in the compressed air energy storage system so that the reactive power output currently output by the power grid is adjusted to the required reactive power, wherein the excitation reference voltage is related to the excitation reference current, and the reactive power is related to the excitation reference voltage.

[0070] It can be understood that the embodiment of the present application controls the compressed air energy storage system to respond to the first component, that is, dynamically adjusts the reactive power output of the compressed air energy storage system. Since the excitation reference voltage is a key parameter for controlling the excitation current, and the reactive power is related to the excitation current, the embodiment of the present application can indirectly adjust the reactive power of the compressed air energy storage system to achieve the required reactive power by adjusting the excitation reference voltage of the generator in the compressed air energy storage system.

[0071] The relationship between the excitation reference voltage and the excitation current is:

[0072] I f = k·(U f -U L );

[0073] Among them, I f is the excitation current, k is the gain of the excitation system, U f is the excitation reference voltage, U L is the saturation voltage of the generator;

[0074] The relationship between reactive power and excitation current is:

[0075]

[0076] Where Q is reactive power, V t is the generator terminal voltage, I f is the excitation current, is the power factor angle.

[0077] Specifically, the embodiment of the present application adjusts the reactive power output of the compressed air energy storage system, that is, controls the excitation voltage of the compressed air energy storage system. In the excitation system of the generator, the excitation reference voltage is a key parameter for controlling the magnitude of the excitation current. f With excitation reference voltage U f The relationship between them is expressed as:

[0078] I f = k·(U f -U L );

[0079] Reactive power Q can be expressed as:

[0080]

[0081] By increasing the excitation reference voltage, the excitation current can be increased, thereby increasing the reactive power. Conversely, reducing the excitation reference voltage will reduce the excitation current, resulting in a reduction in reactive power.

[0082] In an embodiment of the present application, controlling the DC transmission system to respond to the second component includes: obtaining the current bus voltage on the inverter side of the DC transmission system, the maximum value of the inverter trigger angle, and the first DC current command value of the low-voltage current limiting controller; calculating the second DC current command value based on the current bus voltage and the maximum value; selecting the minimum value of the first DC current command value and the second DC current command value as the final DC current command value; and adjusting the DC current of the DC transmission system based on the final DC current command value.

[0083] It can be understood that the embodiment of the present application can control the DC transmission system to respond to the second component, that is, to control the DC current instruction of the DC transmission system, specifically: based on the current bus voltage on the inverter side of the DC transmission system and the maximum value of the inverter trigger angle, the second DC current instruction value is calculated, and the second DC current instruction value is compared with the first DC current instruction value of the voltage current limiting controller, and the minimum value is selected as the final DC current instruction value, and the DC current of the DC transmission system is adjusted based on the final DC current instruction value.

[0084] The calculation formula of the second DC current command value in the embodiment of the present application is:

[0085]

[0086] Among them, γ0 is the inverter turn-off angle, α is the inverter trigger angle, a is the converter transformer ratio, U LI is the inverter side commutation bus voltage, X c is the commutation reactance.

[0087] In an embodiment of the present application, before adjusting the DC current of the DC transmission system based on the final DC current command value, it also includes: obtaining a trigger lead angle output by a constant current controller on the inverter side and a trigger lead angle output by a fixed turn-off angle control on the inverter side; if the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed turn-off angle control on the inverter side, adjusting the DC current of the DC transmission system based on the final DC current command value.

[0088] It can be understood that before the embodiment of the present application adjusts the DC current of the DC transmission system based on the final DC current command value, when it is detected that the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed turn-off angle control on the inverter side, the final DC current command value calculation is put into operation, otherwise it is exited after a delay of 50ms after it is detected that the fault of the AC system on the inverter side is cleared, so that the DC current command value optimization strategy can take effect during the fault period to ensure the turn-off angle margin value of the inverter during the fault period, thereby suppressing the occurrence of continuous commutation failure.

[0089] Specifically, the embodiment of the present application adjusts the DC current instruction of the DC power transmission system as follows:

[0090] By measuring the inverter side commutation bus voltage U in real time LI , the inverter trigger angle can take the maximum value of the trigger angle, then the DC current command value should satisfy:

[0091]

[0092] Among them, γ0 is the inverter turn-off angle, α is the inverter trigger angle, α is the converter transformer ratio, U LI is the inverter side commutation bus voltage, X c is the commutation reactance.

[0093] The above DC current command value calculation method is combined with the low-voltage current limiting controller, and the minimum value of the DC current command values ​​of the two is taken as the final DC current command value. When it is detected that the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed turn-off angle control on the inverter side, the DC current command value calculation is put into operation, and it is exited after a delay of 50ms after the AC system fault on the inverter side is cleared. In this way, the DC current command value optimization strategy can take effect during the fault period to ensure the turn-off angle margin value of the inverter during the fault period, thereby suppressing the occurrence of continuous commutation failure.

[0094] In summary, the coordinated control method of the DC power transmission system and the compressed air energy storage system in the embodiment of the present application is used to suppress commutation failure and stabilize the transient voltage of the DC feed-in bus, and mainly includes:

[0095] 1. Connect the compressed air energy storage system to the DC transmission system to use the reactive power output function of the compressed air energy storage system to support the receiving power grid. The voltage monitoring module monitors the grid operation status in real time, and dynamically adjusts the reactive power output of the compressed air energy storage system according to the voltage changes of the DC transmission system busbar.

[0096] 2. According to the different response time scales of the DC transmission control system and the compressed air energy storage system in controlling the power grid after phase change failure, the receiving end bus voltage deviation is decomposed into high and low parts in the frequency domain using wavelet packet decomposition. The high-frequency signal is responded quickly by the DC transmission control system, and the low-frequency signal is responded persistently by the compressed air energy storage system.

[0097] 3. The compressed air energy storage system and the DC transmission system are controlled in a coordinated manner. According to the respective control characteristics of the DC control system and the compressed air energy storage, the DC transmission system and the compressed air energy storage system respond to the corresponding components. At the same time, according to the dynamic response characteristics of the compressed air energy storage unit and the regulation constraints of the DC transmission system control, a self-optimizing allocation strategy for the DC transmission system and the compressed air energy storage system is proposed.

[0098] The embodiment of the present application realizes efficient coordination between the compressed air energy storage system and the DC power transmission system, and utilizes the characteristics of the compressed air energy storage system with long-lasting response and large adjustment range to provide necessary reactive power support and voltage regulation. This coordinated control gives full play to the response speed characteristics of the DC system and the compressed air energy storage system, realizes the complementary advantages of the two systems in terms of voltage support, and enables the DC power transmission system and the compressed air energy storage system to match the appropriate voltage support component according to their own adjustment margin, dynamic characteristics, and energy storage capacity, and effectively improves the voltage fluctuation of the receiving end bus within the normal working range, thereby suppressing commutation failure.

[0099] The collaborative method of the present application is described below through a specific embodiment. Figure 2 The structure diagram of the coordinated control system of the compressed air energy storage system in the DC system is described, including the following steps:

[0100] 1. Install necessary sensors in the DC transmission system and compressed air energy storage system to collect key operating data of the system in real time, including voltage, current, frequency and load changes. All collected data are sent to the central processing unit through a real-time transmission system to ensure the real-time and accuracy of the data, providing a basis for subsequent analysis. Use advanced data analysis technology to conduct in-depth analysis of the collected data. This will identify possible unstable factors in the power grid and predict power grid events such as commutation failure.

[0101] 2. When the system detects voltage instability or predicts possible commutation failure, the reactive output of the compressed air energy storage system is adjusted quickly. This rapid adjustment can maintain the voltage stability of the power grid and prevent voltage fluctuations and system instability.

[0102] 3. Establish a rapid response mechanism to allow the compressed air energy storage system to quickly adjust its operating status when it detects grid anomalies or the risk of phase change failure.

[0103] 4. After the system is put into operation, continuously monitor its performance, including response time, regulation accuracy and system stability. This monitoring helps identify any potential problems and ensures the optimization of system operation.

[0104] The specific execution steps of the collaborative method are as follows: Figure 3 As shown, the following steps are included:

[0105] 1. Data sampling.

[0106] The voltage monitoring module monitors the grid operation status in real time and obtains the bus voltage deviation on the inverter side of the DC transmission system.

[0107] 2. Wavelet packet decomposition.

[0108] Wavelet packet decomposition is used to decompose the inverter-side bus voltage deviation into high-frequency and low-frequency parts in the frequency domain. The DC control system and the compressed air energy storage system respond to components in different frequency bands respectively, giving full play to the rapid response capability of the DC control system and the durability of the compressed air energy storage system unit output.

[0109] 3. Calculate the compressed air energy storage system ( Figure 3 The output power of the pressure storage system (referred to as the pressure storage system in this article) is:

[0110] Determine whether the output of the compressed air energy storage system meets the constraints of the following formula. If the constraints are met, no adjustment will be made.

[0111]

[0112] in, is the lower limit of the energy storage output power at time t, is the upper limit of the energy storage output power at time t.

[0113] If it is not satisfied, the adjustment strategy of the compressed air energy storage system is to gradually reduce the low-frequency component Δf from large to small. L , update Δf L At the same time, the DC transmission control system temporarily expands its control range.

[0114] 4. Calculation of DC transmission system ( Figure 3 The control margin constraint of the DC system is referred to as the DC system in this paper.

[0115] Determine whether the DC transmission control system meets the control margin constraint. If it does, no adjustment will be made. If not, the DC transmission control system adjustment strategy is: determine whether the compressed air energy storage system has a margin output. If so, gradually reduce the high-frequency component Δf from small to large. H The discarded amount is borne by the compressed air energy storage, giving full play to the wide adjustment range of the compressed air energy storage system.

[0116] According to the collaborative control method of a DC transmission system and a compressed air energy storage system proposed in the embodiment of the present application, when the grid operation state is abnormal or the commutation fails, the compressed air energy storage system and the DC transmission system can be collaboratively controlled based on the bus voltage deviation on the inverter side of the DC transmission system. The respective characteristics of the DC transmission system and the compressed air energy storage system are utilized to achieve complementary advantages of the two systems in voltage support, effectively improve the problem of bus voltage fluctuation on the inverter side, thereby suppressing commutation failure, and further improving the stability, safety and reliability of the power system operation.

[0117] Next, a coordinated control device for a DC power transmission system and a compressed air energy storage system proposed in an embodiment of the present application will be described with reference to the accompanying drawings.

[0118] Figure 4 It is a block diagram of a coordinated control device of a direct current transmission system and a compressed air energy storage system according to an embodiment of the present application.

[0119] like Figure 4 As shown, the DC power transmission system and compressed air energy storage system coordinated control device 10 includes: a first acquisition module 100, a second acquisition module 200 and a control module 300.

[0120] Among them, the first acquisition module 100 is used to obtain the current operating state and the current commutation state of the power grid; the second acquisition module 200 is used to obtain the bus voltage deviation on the inverter side of the DC transmission system if the current operating state is a preset abnormal state or the current commutation state is a commutation failure state; the control module 300 is used to coordinately control the compressed air energy storage system and the DC transmission system based on the bus voltage deviation.

[0121] In an embodiment of the present application, the control module 300 is further used to: decompose the bus voltage deviation into a first component and a second component in the frequency domain using a wavelet packet function, the frequency of the first component being lower than the frequency of the second component; control the compressed air energy storage system to respond to the first component; and control the direct current transmission system to respond to the second component.

[0122] In an embodiment of the present application, the control module 300 is further used to: obtain the required reactive power of the power grid; adjust the excitation reference voltage of the generator in the compressed air energy storage system so that the reactive power output currently output by the power grid is adjusted to the required reactive power, wherein the excitation reference voltage is related to the excitation reference current, and the reactive power is related to the excitation reference voltage.

[0123] In the embodiment of the present application, the relationship between the excitation reference voltage and the excitation current is:

[0124] I f = k·(U f -U L );

[0125] Among them, I f is the excitation current, k is the gain of the excitation system, U f is the excitation reference voltage, U L is the saturation voltage of the generator;

[0126] The relationship between reactive power and excitation current is:

[0127]

[0128] Where Q is reactive power, V t is the generator terminal voltage, I f is the excitation current, is the power factor angle.

[0129] In an embodiment of the present application, the control module 300 is further used to: obtain the current bus voltage on the inverter side of the DC transmission system, the maximum value of the inverter trigger angle, and the first DC current command value of the low-voltage current limiting controller; calculate the second DC current command value based on the current bus voltage and the maximum value; select the minimum value of the first DC current command value and the second DC current command value as the final DC current command value; and adjust the DC current of the DC transmission system based on the final DC current command value.

[0130] In the embodiment of the present application, the device 10 of the embodiment of the present application further includes: an adjustment module.

[0131] Among them, the adjustment module is used to obtain the trigger lead angle output by the constant current controller on the inverter side and the trigger lead angle output by the fixed shutdown angle control on the inverter side before adjusting the DC current of the DC transmission system based on the final DC current command value; if the trigger lead angle output by the constant current controller on the inverter side is greater than the trigger lead angle output by the fixed shutdown angle control on the inverter side, the DC current of the DC transmission system is adjusted based on the final DC current command value.

[0132] In the embodiment of the present application, the device 10 of the embodiment of the present application further includes: a judgment module.

[0133] Among them, the judgment module is used to judge whether the compressed air energy storage system meets the first preset constraint condition after decomposing the bus voltage deviation into the first component and the second component in the frequency domain by using the wavelet packet function; if the first preset constraint condition is met, the quantity ratio of the first component and the second component is not adjusted, otherwise the quantity of the first component is reduced; judge whether the direct current transmission system meets the second preset constraint condition; if the second preset constraint condition is met, the quantity ratio of the first component and the second component is not adjusted, otherwise it is judged whether there is additional reactive power in the compressed air energy storage system; if there is additional reactive power, the quantity of the second component is reduced, and the reduced second component is transferred to the compressed air energy storage system.

[0134] It should be noted that the aforementioned explanation of the embodiment of the coordinated control method of the DC power transmission system and the compressed air energy storage system is also applicable to the coordinated control device of the DC power transmission system and the compressed air energy storage system of this embodiment, and will not be repeated here.

[0135] According to the coordinated control device of the DC transmission system and the compressed air energy storage system proposed in the embodiment of the present application, when the operating state of the power grid is abnormal or the commutation fails, the compressed air energy storage system and the DC transmission system can be coordinated and controlled based on the bus voltage deviation on the inverter side of the DC transmission system. The respective characteristics of the DC transmission system and the compressed air energy storage system are utilized to achieve complementary advantages of the two systems in voltage support, effectively improve the problem of bus voltage fluctuation on the inverter side, thereby suppressing commutation failure, and further improving the stability, safety and reliability of the power system operation.

[0136] Figure 5 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include:

[0137] A memory 501 , a processor 502 , and a computer program stored in the memory 501 and executable on the processor 502 .

[0138] When the processor 502 executes the program, the coordinated control method of the DC power transmission system and the compressed air energy storage system provided in the above embodiment is implemented.

[0139] Furthermore, the electronic device further comprises:

[0140] The communication interface 503 is used for communication between the memory 501 and the processor 502 .

[0141] The memory 501 is used to store computer programs that can be executed on the processor 502 .

[0142] The memory 501 may include a high-speed RAM memory, and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0143] If the memory 501, the processor 502 and the communication interface 503 are implemented independently, the communication interface 503, the memory 501 and the processor 502 can be connected to each other through a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0144] Optionally, in a specific implementation, if the memory 501, the processor 502 and the communication interface 503 are integrated on a chip, the memory 501, the processor 502 and the communication interface 503 can communicate with each other through an internal interface.

[0145] The processor 502 may be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application.

[0146] An embodiment of the present application also provides a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed by a processor, the method for coordinated control of a DC power transmission system and a compressed air energy storage system as described above is implemented.

[0147] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0148] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0149] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0150] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one or a combination of multiple of the following technologies known in the art: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0151] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

Claims

1. A method for coordinated control of a DC power transmission system and a compressed air energy storage system, characterized in that: The following steps are involved: Obtain the current operating status and current commutation status of the power grid; If the current operating state is a preset abnormal state or the current commutation state is a commutation failure state, obtaining a bus voltage deviation on the inverter side of the direct current transmission system; The compressed air energy storage system and the direct current power transmission system are cooperatively controlled based on the bus voltage deviation.

2. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 1 is characterized in that: The method of collaboratively controlling the compressed air energy storage system and the direct current power transmission system based on the bus voltage deviation includes: Decomposing the bus voltage deviation into a first component and a second component in the frequency domain by using a wavelet packet function, wherein the frequency of the first component is lower than the frequency of the second component; controlling the compressed air energy storage system to respond to the first component; The DC power transmission system is controlled to respond to the second component.

3. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 2 is characterized in that: The controlling the compressed air energy storage system to respond to the first component comprises: Obtaining the required reactive power of the power grid; Adjust the excitation reference voltage of the generator in the compressed air energy storage system so that the reactive power output currently output by the power grid is adjusted to the required reactive power, wherein the excitation reference voltage is related to the excitation current, and the reactive power is related to the excitation reference voltage.

4. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 3 is characterized in that: The relationship between the excitation reference voltage and the excitation current is: AND f =k·(U f -IN L ); Among them, I f is the excitation current, k is the gain of the excitation system, U f is the excitation reference voltage, U L is the saturation voltage of the generator; The relationship between the reactive power and the excitation current is: Where Q is reactive power, V t is the generator terminal voltage, I f is the excitation current, is the power factor angle.

5. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 2, characterized in that: The controlling the DC power transmission system to respond to the second component comprises: Acquire the current bus voltage on the inverter side of the DC power transmission system, the maximum value of the inverter trigger angle, and the first DC current command value of the low-voltage current limiting controller; Calculate a second DC current command value based on the current bus voltage and the maximum value; Selecting the minimum value between the first DC current command value and the second DC current command value as the final DC current command value; The DC current of the DC power transmission system is adjusted based on the final DC current command value.

6. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 5 is characterized in that: Before adjusting the DC current of the DC power transmission system based on the final DC current command value, the method further includes: Obtaining the trigger advance angle output by the inverter-side constant current controller and the trigger advance angle output by the inverter-side fixed turn-off angle control; If the trigger lead angle output by the inverter-side constant current controller is greater than the trigger lead angle output by the inverter-side fixed turn-off angle control, the DC current of the DC power transmission system is adjusted based on the final DC current command value.

7. The coordinated control method of a DC power transmission system and a compressed air energy storage system according to claim 2, characterized in that: After decomposing the bus voltage deviation into a first component and a second component in the frequency domain by using a wavelet packet function, the method further includes: Determining whether the compressed air energy storage system meets a first preset constraint condition; If the first preset constraint condition is met, the quantity ratio of the first component to the second component is not adjusted; otherwise, the quantity of the first component is reduced; Determining whether the DC power transmission system satisfies a second preset constraint condition; If the second preset constraint condition is met, the quantity ratio of the first component and the second component is not adjusted; otherwise, it is determined whether there is additional reactive power in the compressed air energy storage system; If the additional reactive power exists, the amount of the second component is reduced, and the reduced second component is transferred to the compressed air energy storage system.

8. A coordinated control device for a DC power transmission system and a compressed air energy storage system, characterized in that: include: A first acquisition module is used to acquire the current operation state and current commutation state of the power grid; A second acquisition module is used to acquire a bus voltage deviation on the inverter side of the direct current power transmission system if the current operating state is a preset abnormal state or the current commutation state is a commutation failure state; A control module is used to collaboratively control the compressed air energy storage system and the direct current power transmission system based on the bus voltage deviation.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method for coordinated control of a direct current transmission system and a compressed air energy storage system as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: The computer program or instruction is executed by a processor to implement the coordinated control method of a direct current transmission system and a compressed air energy storage system as described in any one of claims 1 to 7.

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