Method, system and equipment for enhancing power angle stability of power system and medium

Abstract

The invention discloses a power angle stability enhancing method, system and device of a power system and a medium. The method comprises the steps of obtaining current saturation mode data and voltage source mode data of the power system; adjusting a damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy; adjusting a quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy; and performing control processing on the power system according to the first control strategy and the second control strategy. The embodiment of the invention can enhance the power angle stability of the power system, and can be widely applied to the technical field of power grids.

Description

Technical Field

[0001] The present application relates to the technical field of power grids, and particularly relates to a method, a system, a device and a medium for enhancing the power angle stability of a power system. Background Art

[0002] With the low-carbon transformation of global energy, the proportion of equipment connected to the grid via converters is continuously increasing. The virtual synchronous generator (VSG) control of the converter can simulate the external characteristics of the synchronous generator and actively participate in the frequency and voltage regulation of the power grid. Similar to the synchronous generator, the virtual synchronous generator has a synchronous stability problem. In related technologies, the transient power angle swing of the virtual synchronous generator is suppressed by adjusting the active power reference value of the virtual synchronous generator, or the power angle stability is improved by changing the accelerating and decelerating areas. However, in practical applications, it is found that these methods can only be applied to a single-machine infinite system containing a virtual synchronous generator, ignoring the influence of the power angle stability between the virtual synchronous generator and other voltage sources, resulting in difficulty in truly achieving power angle synchronization between the virtual synchronous generator and the synchronous generators of other voltage sources, and affecting the stability of the power system.

[0003] In summary, the technical problems existing in the related technologies need to be improved. Summary of the Invention

[0004] The main purpose of the embodiments of the present application is to propose a method, a system, a device and a medium for enhancing the power angle stability of a power system, which can improve the power angle stability of the power system.

[0005] To achieve the above object, on the one hand, an embodiment of the present application proposes a method for enhancing the power angle stability of a power system, the method including:

[0006] Obtain the current saturation mode data and voltage source mode data of the power system;

[0007] Adjust the damping coefficient of the virtual synchronous generator according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous generator, so as to control the power angle difference between the virtual synchronous generator and the external network synchronous generator;

[0008] Adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous generator according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous generator according to the quadrature-axis voltage feedback coefficient of the virtual synchronous generator;

[0009] Control the power system according to the first control strategy and the second control strategy.

[0010] In some embodiments, obtaining the current saturation mode data of the power system includes the following steps:

[0011] Collect the high - voltage side voltage amplitude of the step - up transformer in the grid - forming converter;

[0012] Collect and process the low - voltage side frequency of the step - up transformer in the virtual synchronous machine in the current saturation mode to obtain the external grid frequency;

[0013] Perform active power loop calculation processing on the virtual synchronous machine to obtain the virtual synchronous machine frequency;

[0014] Obtain the current saturation mode data based on the high - voltage side voltage amplitude, the external grid frequency, and the virtual synchronous machine frequency.

[0015] In some embodiments, collecting and processing the low - voltage side frequency of the step - up transformer in the virtual synchronous machine in the current saturation mode to obtain the external grid frequency includes the following steps:

[0016] Collect the three - phase voltage vectors of the low - voltage side of the step - up transformer of the virtual synchronous machine through a signal acquisition system;

[0017] Input the three - phase voltage vectors into a phase - locked loop, and output the external grid frequency through the phase - locked loop.

[0018] In some embodiments, the voltage source mode data of the power system includes the following steps:

[0019] Collect and process the quadrature - axis component of the output current of the virtual synchronous machine to obtain the quadrature - axis component current;

[0020] Collect and process the active power of the virtual synchronous machine to obtain the active power;

[0021] Collect and process the quadrature - axis component of the low - voltage side node voltage of the step - up transformer in the virtual synchronous machine to obtain the quadrature - axis component voltage;

[0022] Obtain the voltage source mode data based on the quadrature - axis component current, the active power, and the quadrature - axis component voltage.

[0023] In some embodiments, adjusting the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain the first control strategy includes the following steps:

[0024] Obtain the high - voltage side voltage amplitude, the external grid frequency, and the virtual synchronous machine frequency according to the current saturation mode data;

[0025] When the high - voltage side voltage amplitude is greater than a preset threshold, set the damping coefficient of the virtual synchronous machine to the steady - state damping coefficient;

[0026] When the amplitude of the high - voltage side voltage is less than or equal to the preset threshold, calculate the damping coefficient of the virtual synchronous machine according to the external grid frequency and the virtual synchronous machine frequency;

[0027] Control the power - angle acceleration of the virtual synchronous machine according to the damping coefficient of the virtual synchronous machine, and determine the first control strategy.

[0028] In some embodiments, the calculating the damping coefficient of the virtual synchronous machine according to the external grid frequency and the virtual synchronous machine frequency includes the following steps:

[0029] Subtract the external grid frequency from the virtual synchronous machine frequency to obtain a frequency difference;

[0030] Multiply the frequency difference by a preset first constant, and add the multiplication result to the steady - state damping coefficient to obtain the damping coefficient of the virtual synchronous machine.

[0031] In some embodiments, the adjusting the quadrature - axis voltage feedback coefficient of the virtual synchronous machine according to the voltage - source mode data to obtain a second control strategy includes the following steps:

[0032] Calculate the quadrature - axis voltage feedback coefficient of the virtual synchronous machine according to the voltage - source mode data;

[0033] Update the reference value of the active - power loop of the virtual synchronous machine with the quadrature - axis voltage feedback coefficient of the virtual synchronous machine to obtain an updated reference value;

[0034] Update the control equation of the active - power loop according to the updated reference value, so as to adjust the frequency and power angle of the virtual synchronous machine to obtain the second control strategy.

[0035] To achieve the above object, another aspect of the embodiments of the present application proposes a power system power - angle stability enhancement system, and the system includes:

[0036] A first module, configured to obtain the current saturation mode data and voltage - source mode data of the power system;

[0037] A second module, configured to adjust the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous machine, so as to control the power - angle difference between the virtual synchronous machine and the external - network synchronous machine;

[0038] The third module is configured to adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous machine according to the quadrature-axis voltage feedback coefficient of the virtual synchronous machine.

[0039] The fourth module is configured to perform control processing on the power system according to the first control strategy and the second control strategy.

[0040] To achieve the above object, on the other hand, an embodiment of the present application provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the method described above is implemented.

[0041] To achieve the above object, on the other hand, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the method described above is implemented.

[0042] The embodiments of the present application at least include the following beneficial effects: The present application provides a method, a system, a device, and a medium for enhancing the power angle stability of a power system. This solution obtains the current saturation mode data and voltage source mode data of the power system, and adjusts the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy, which can adjust the damping coefficient of the virtual synchronous machine based on the current saturation mode data to reduce the power angle difference, thereby improving the power angle stability between the virtual synchronous machine and the external network synchronous machine under the current saturation mode. In addition, this solution adjusts the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy, which can adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to reduce the instability risk between the virtual synchronous machine and the external network synchronous machine, and improve the power angle stability between the virtual synchronous machine and the external network synchronous machine under the voltage source mode. Description of the Drawings

[0043] Figure 1 is a flowchart of a method for enhancing the power angle stability of a power system provided by an embodiment of the present application;

[0044] Figure 2 is a power angle stability enhancement strategy diagram of a virtual synchronous machine control type converter device provided by an embodiment of the present application;

[0045] Figure 3 is a multi-machine two-area system diagram provided by an embodiment of the present application;

[0046] Figure 4 is a power angle difference curve diagram between a virtual synchronous machine and an external network synchronous machine provided by an embodiment of the present application;

[0047] Figure 5 It is the direct-axis current curve diagram of a virtual synchronous machine under experimental group 2 provided by an embodiment of the present application;

[0048] Figure 6 It is the active power curve diagram of a virtual synchronous machine provided by an embodiment of the present application;

[0049] Figure 7 It is the structural schematic diagram of a power system power angle stability enhancement system provided by an embodiment of the present application;

[0050] Figure 8 It is the hardware structural schematic diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the embodiments of the present application. They are only examples of systems and methods that are consistent with some aspects of the embodiments of the present application as detailed in the appended claims.

[0052] It can be understood that the terms "first", "second", etc. used in the present application can be used in this text to describe various concepts, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information can also be called the second information, and similarly, the second information can also be called the first information. Depending on the context, the words "if", "when" used herein can be interpreted as "when...", "while...", or "in response to determining".

[0053] The terms "at least one", "multiple", "each", "any one", etc. used in the present application, at least one includes one, two or more than two, multiple includes two or more than two, each refers to each of the corresponding multiple, and any one refers to any one of the multiple.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0055] Before elaborating on the embodiments of the present application in detail, some nouns and terms involved in the embodiments of the present application are first explained, and the nouns and terms involved in the embodiments of the present application are applicable to the following explanations.

[0056] 1) Virtual synchronous generator (VSG), also known as virtual synchronous generator, is a power electronics technology that enables new energy power generation equipment to have the ability to actively support the power grid and improve power grid stability by simulating the operating mechanism of synchronous generators. The virtual synchronous generator has characteristics such as high-efficiency collaboration, fast response, stable reliability, strong scalability, and high economy. It can reduce the operating costs of distributed energy resources and improve economic benefits.

[0057] 2) The voltage source mode is a control mode of the virtual synchronous generator, usually the default operating mode, which can simulate the voltage regulation characteristics of traditional synchronous generators. In this mode, the virtual synchronous generator maintains the stable operation of the power grid by controlling the amplitude and frequency of the output voltage.

[0058] 3) The current saturation mode is another control mode of the virtual synchronous generator, which is a current limiting operation mode. When the output current of the virtual synchronous generator exceeds the set limit value, the system will automatically switch to the current saturation mode to protect the inverter and the load. The virtual synchronous generator usually needs to dynamically switch between the voltage source mode and the current saturation mode according to the operating conditions.

[0059] With the low-carbon transformation of the global energy, the proportion of equipment connected to the grid through converters is increasing continuously. Since the virtual synchronous generator (VSG) control of the converter can simulate the external characteristics of the synchronous machine and actively participate in the frequency and voltage regulation of the power grid, the control characteristics of VSG have attracted more and more attention from the academic and engineering circles. Similar to the synchronous machine, VSG also has a synchronous stability problem.

[0060] In related technologies, there are methods to suppress the transient power angle swing of VSG by adjusting the active power reference value of VSG. There is also an analysis of the transient stability of the VSG grid-connected system based on the equal area criterion, and a modal adaptive power angle control method to improve the transient stability is proposed. This part of the research improves the power angle stability by changing the accelerating and decelerating areas. In addition, considering that the overcurrent capacity of the converter is significantly weaker than that of the synchronous machine, some scholars have paid attention to the impact of the current limiting link of VSG on the transient stability of the system. Related technologies have found that the transient switching operation mode introduced by the current saturation limit imposes another constraint on the equilibrium point, reducing the decelerating area of the grid-forming converter and deteriorating the transient stability. Related technologies have also analyzed the conditions for VSG to return to the normal mode after current saturation and proposed an enhanced control method for anti-saturation stability.

[0061] However, in practical applications, it is found that these methods can only be applied to single-machine infinite bus systems with virtual synchronous machines, ignoring the impact of the power angle stability between the virtual synchronous machine and other voltage sources, resulting in difficulty in truly achieving power angle synchronization between the virtual synchronous machine and the synchronous machines of other voltage sources, and affecting the stability of the power system.

[0062] In view of this, in the embodiments of the present application, a method, system, device and medium for enhancing the power angle stability of a power system are provided. This solution obtains the current saturation mode data and voltage source mode data of the power system, adjusts the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain the first control strategy, and can adjust the damping coefficient of the virtual synchronous machine based on the current saturation mode data to reduce the power angle difference, thereby improving the power angle stability between the virtual synchronous machine and the external network synchronous machine under the current saturation mode. In addition, this solution adjusts the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain the second control strategy, and can adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to reduce the instability risk between the virtual synchronous machine and the external network synchronous machine, and improve the power angle stability between the virtual synchronous machine and the external network synchronous machine under the voltage source mode.

[0063] A method for enhancing the power angle stability of a power system provided by the embodiments of the present application relates to the technical field of power grids and is applicable to the power angle stability enhancement strategy of converter grid-connected equipment controlled by virtual synchronous machines. The method for enhancing the power angle stability of a power system provided by the embodiments of the present application can be applied to grid equipment, can also be applied to a server, or can be software running on grid equipment or a server. In some embodiments, the grid equipment can be a converter device controlled by a virtual synchronous machine, etc., but is not limited thereto; the server side can be configured as an independent physical server, can also be configured as a server cluster or distributed system composed of multiple physical servers, can also be configured as a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The server can also be a node server in a blockchain network; the software can be an application for implementing a method for enhancing the power angle stability of a power system, etc., but is not limited to the above forms.

[0064] This application can be used in numerous general - purpose or special - purpose computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multi - processor systems, micro - processor - based systems, set - top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and so on. This application can be described in the general context of computer - executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. This application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0065] Figure 1 is an alternative flowchart of a method for enhancing the power - angle stability of a power system provided by an embodiment of this application. Figure 1 The method in may include but is not limited to steps S101 to S104.

[0066] Step S101: Obtain the current saturation mode data and voltage source mode data of the power system.

[0067] Step S102: Adjust the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous machine, thereby controlling the power - angle difference between the virtual synchronous machine and the external - network synchronous machine.

[0068] Step S103: Adjust the quadrature - axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous machine according to the quadrature - axis voltage feedback coefficient of the virtual synchronous machine.

[0069] Step S104: Control - process the power system according to the first control strategy and the second control strategy.

[0070] Steps S101 to S104 shown in the embodiments of the present application first obtain the current saturation mode data and voltage source mode data of the power system. The power system is a power system applicable to a virtual synchronous machine control converter device. The current saturation mode and voltage source mode are control modes of the virtual synchronous machine. The current saturation mode data is data collected when the virtual synchronous machine is in the current saturation mode, and the voltage source mode data is data collected when the virtual synchronous machine is in the voltage source mode. In order to improve the power angle stability between the virtual synchronous machine and the external network synchronous machine in the current saturation mode, the damping coefficient of the virtual synchronous machine is adjusted according to the current saturation mode data, a variable damping control strategy for the virtual synchronous machine is constructed, and a first control strategy is obtained. The damping coefficient of the virtual synchronous machine can be adjusted through the first control strategy, thereby controlling the power angle difference between the virtual synchronous machine and the external network synchronous machine. In order to improve the power angle stability between the virtual synchronous machine and the external network synchronous machine in the voltage source mode, a quadrature-axis (q-axis) voltage feedback control strategy for the virtual synchronous machine is constructed according to the voltage source mode data, and a second control strategy is obtained. The frequency and power angle of the virtual synchronous machine are adjusted according to the quadrature-axis voltage feedback coefficient of the virtual synchronous machine through the second control strategy. Thus, a power angle stability enhancement strategy applicable to the virtual synchronous machine control converter device is jointly constituted by the first control strategy and the second control strategy, and the power system is controlled according to the power angle stability enhancement strategy to improve the power angle stability of the power system.

[0071] In step S101 of some embodiments, the obtaining of the current saturation mode data of the power system includes the following steps:

[0072] Collect the high-side voltage amplitude of the step-up transformer in the grid-forming converter;

[0073] Collect and process the low-side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode to obtain the external grid frequency;

[0074] Perform active power loop calculation processing on the virtual synchronous machine to obtain the virtual synchronous machine frequency;

[0075] Obtain the current saturation mode data according to the high-side voltage amplitude, the external grid frequency, and the virtual synchronous machine frequency.

[0076] In the embodiments of the present application, to obtain data of the virtual synchronous machine in the current saturation mode in the power system, the high-side voltage amplitude of the step-up transformer in the grid-forming converter in the power system can be collected by a sensor, and the low-side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode can be collected and processed. Since when the virtual synchronous machine is in the current saturation mode, the virtual synchronous machine cannot autonomously adjust the frequency, the control system will give priority to ensuring synchronization and preventing out-of-step, and will rely on the phase-locked loop (PLL) to lock the grid frequency, which means that the frequency of the step-up transformer will be forced to be consistent with the grid frequency. Therefore, the low-side frequency of the step-up transformer can represent the synchronous machine frequency in the external power grid, and thus the external power grid frequency can be obtained. Then, the active power loop of the virtual synchronous machine is calculated to obtain the virtual synchronous machine frequency, which refers to the internal control reference frequency generated by simulating the rotor dynamic equation of the synchronous generator and is used to control the phase and frequency of the inverter output voltage. Finally, the obtained high-side voltage amplitude, external power grid frequency, and virtual synchronous machine frequency are used as data in the current saturation mode.

[0077] One of the technical solutions in the above technical solutions has the following advantages or beneficial effects: By obtaining the data in the current saturation mode in the embodiments of the present application, the virtual synchronous machine can be controlled and adjusted in the current saturation mode according to the obtained data, thereby improving the power angle stability of the virtual synchronous machine.

[0078] In some embodiments, the collecting and processing of the low-side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode to obtain the external power grid frequency includes the following steps:

[0079] Collect the three-phase voltage vectors on the low side of the step-up transformer of the virtual synchronous machine through a signal acquisition system;

[0080] Input the three-phase voltage vectors into the phase-locked loop, and output the external power grid frequency through the phase-locked loop.

[0081] In the embodiments of the present application, to collect the low-side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode, the three-phase voltage vectors on the low side of the step-up transformer in the virtual synchronous machine can be collected through a signal acquisition system. Specifically, voltage transformers can be used to collect the three-phase voltages respectively, and the three-phase voltage vectors can be obtained through synchronous sampling technology. Digital voltage sensors, etc. can also be used to obtain the three-phase voltage vectors. Finally, by inputting the three-phase voltage vectors into the phase-locked loop, the external power grid frequency is output through the phase-locked loop.

[0082] One of the technical solutions in the above technical solutions has the following advantages or beneficial effects: In the embodiment of the present application, by collecting the low-voltage side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode and using it as the external grid frequency, the external grid frequency and the virtual synchronous machine frequency can be compared to determine the power angle stability, so as to subsequently adjust the virtual synchronous machine according to the current saturation mode data to enhance the power angle stability.

[0083] In some embodiments, the voltage source mode data of the power system includes the following steps:

[0084] Collect and process the quadrature-axis component of the output current of the virtual synchronous machine to obtain the quadrature-axis component current;

[0085] Collect and process the active power of the virtual synchronous machine to obtain the active power;

[0086] Collect and process the quadrature-axis component of the low-voltage side node voltage of the step-up transformer in the virtual synchronous machine to obtain the quadrature-axis component voltage;

[0087] Obtain the voltage source mode data according to the quadrature-axis component current, the active power, and the quadrature-axis component voltage.

[0088] In the embodiment of the present application, the voltage source mode data is the data collected when the virtual synchronous machine is in the voltage source mode. By collecting the quadrature-axis (q-axis) component of the output current of the virtual synchronous machine, the quadrature-axis component current is obtained, and the active power of the virtual synchronous machine is collected and processed to obtain the active power. The quadrature-axis component current and the active power can jointly characterize the risk of reverse absorption of the active power of the virtual synchronous machine. Reverse absorption of the active power refers to the phenomenon that the virtual synchronous machine absorbs active power from the power grid during operation. It can be judged according to the value of the active power. When the active power is less than zero, it indicates that reverse absorption occurs. By collecting and processing the quadrature-axis component of the low-voltage side node voltage of the step-up transformer in the virtual synchronous machine, the quadrature-axis component voltage is obtained. The quadrature-axis component voltage can be used to characterize the instability risk of the virtual synchronous machine and the external grid synchronous machine in the voltage source mode. Since the quadrature-axis voltage is equal to 0 in the steady state, and under transient faults, due to the unequal frequencies of the virtual synchronous machine and the external power grid, the quadrature-axis voltage is not 0. Therefore, the greater the deviation of the quadrature-axis voltage, the greater the frequency difference between the virtual synchronous machine and the external synchronous machine, and the greater the synchronous instability risk. Therefore, the quadrature-axis voltage can be introduced into the active power loop of the virtual synchronous machine. When the deviation between the detected quadrature-axis voltage and 0 becomes larger, the active power command of the virtual synchronous machine will adaptively change to adjust the frequency of the virtual synchronous machine, so as to reduce the frequency deviation between the virtual synchronous machine and the external frequency and enhance the power angle stability of the power system.

[0089] One of the technical solutions in the above technical solution has the following advantages or beneficial effects: By collecting the voltage source mode data of the power system, the virtual synchronous machine in the voltage source mode can be adjusted according to the collected data, thereby enhancing the power angle stability of the power system.

[0090] In some embodiments, the adjusting and processing the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy includes the following steps:

[0091] Obtain the high-voltage side voltage amplitude, the external grid frequency, and the virtual synchronous machine frequency according to the current saturation mode data;

[0092] When the high-voltage side voltage amplitude is greater than a preset threshold, set the damping coefficient of the virtual synchronous machine to the steady-state damping coefficient;

[0093] When the high-voltage side voltage amplitude is less than or equal to the preset threshold, calculate the damping coefficient of the virtual synchronous machine according to the external grid frequency and the virtual synchronous machine frequency;

[0094] Control the power angle acceleration of the virtual synchronous machine according to the damping coefficient of the virtual synchronous machine, and determine the first control strategy.

[0095] In the embodiment of the present application, the high-voltage side voltage amplitude, the external grid frequency, and the virtual synchronous machine frequency can be obtained according to the current saturation mode data. Among them, the first control strategy is used to adjust the damping coefficient of the virtual synchronous machine to enhance the power angle stability. Specifically, by comparing the high-voltage side voltage amplitude with a preset threshold, the high-voltage side voltage amplitude is a per-unit value. The per-unit value is a relative unit system and is a commonly used numerical marking method in power system analysis and engineering calculations, representing the relative values of various physical quantities and parameters, with the unit of pu. The preset threshold is set to 0.4 pu. When the high-voltage side voltage amplitude is greater than the preset threshold, the damping coefficient of the virtual synchronous machine is set to the steady-state damping coefficient, and the steady-state damping coefficient is the damping coefficient in the steady state before the fault. When the high-voltage side voltage amplitude is less than or equal to the preset threshold, the damping coefficient of the virtual synchronous machine is calculated according to the external grid frequency and the virtual synchronous machine frequency. Therefore, by adjusting the damping coefficient of the virtual synchronous machine, the power angle acceleration of the virtual synchronous machine is controlled. The specific first control strategy is that when the virtual synchronous machine frequency is greater than the external grid frequency, by increasing the damping coefficient, the power angle acceleration of the virtual synchronous machine is suppressed, thereby reducing the power angle difference between the virtual synchronous machine and the external network synchronous machine. When the frequency of the virtual synchronous machine is less than the external grid frequency, by reducing the damping coefficient, it is beneficial to the power angle acceleration of the virtual synchronous machine, thereby reducing the power angle difference between the virtual synchronous machine and the external network synchronous machine. The power angle stability of the power system can be enhanced through the first control strategy.

[0096] One of the above technical solutions has the following advantages or beneficial effects: In the embodiment of the present application, the damping coefficient is adjusted through the first control strategy, so as to control the power angle acceleration of the virtual synchronous machine, thereby reducing the power angle difference between the virtual synchronous machine and the external synchronous machine, and enhancing the power angle stability of the power system.

[0097] In some embodiments, calculating the damping coefficient of the virtual synchronous machine according to the external grid frequency and the virtual synchronous machine frequency includes the following steps:

[0098] Subtract the external grid frequency from the virtual synchronous machine frequency to obtain a frequency difference;

[0099] Multiply the frequency difference by a preset first constant, and add the multiplication result to the steady-state damping coefficient to obtain the damping coefficient of the virtual synchronous machine.

[0100] In the embodiment of the present application, by subtracting the external grid frequency from the virtual synchronous machine frequency, a frequency difference is obtained. This frequency difference represents the stability between the virtual synchronous machine and the external synchronous machine. By presetting a constant greater than zero as the first constant, multiplying the frequency difference by the first constant, and then adding the multiplication result to the steady-state damping coefficient to obtain the damping coefficient of the virtual synchronous machine. Therefore, the first control strategy can give a calculation formula for the damping coefficient of the virtual synchronous machine, as shown in the following formula:

[0101]

[0102] In the formula, D represents the damping coefficient, D 0 represents the steady-state damping coefficient, U PCC represents the high-voltage side voltage amplitude, K D0 represents a constant greater than zero, f VSG represents the virtual synchronous machine frequency, f w represents the external grid frequency.

[0103] One of the above technical solutions has the following advantages or beneficial effects: In the embodiment of the present application, the damping coefficient is adjusted through the first control strategy, so as to control the power angle acceleration of the virtual synchronous machine, thereby reducing the power angle difference between the virtual synchronous machine and the external synchronous machine, and enhancing the power angle stability of the power system.

[0104] In some embodiments, adjusting the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy includes the following steps:

[0105] Calculate the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data;

[0106] Update the reference value of the active power loop of the virtual synchronous machine by using the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to obtain an updated reference value;

[0107] Update the control equation of the active power loop according to the updated reference value, so as to adjust the frequency and power angle of the virtual synchronous machine, and obtain the second control strategy.

[0108] In the embodiments of the present application, by introducing the quadrature-axis voltage feedback into the active power loop of the virtual synchronous machine, the following formula can be obtained:

[0109] P ref = P ref0 + K Vq U q ;

[0110] In the formula, P ref represents the output reference active power value, P ref0 is the steady-state active power command value of the virtual synchronous machine, K Vq is the feedback coefficient, and U q is the quadrature-axis voltage at the low-voltage side of the step-up transformer of the virtual synchronous machine. When the feedback coefficient is a constant, the quadrature-axis voltage feedback control adjusts the frequency and power angle of the virtual synchronous machine according to the detected deviation value of the quadrature-axis voltage and the adaptive change of the active power command of the virtual synchronous machine. By changing the feedback coefficient into a coefficient that adaptively changes according to the risk, it can be ensured that the proposed control strategy has adaptability in different risk scenarios. In the embodiments of the present application, the quadrature-axis voltage feedback coefficient of the virtual synchronous machine can be calculated according to the voltage source mode data, and the voltage source mode data includes the quadrature-axis component current, active power, and quadrature-axis component voltage. Among them, the calculation formula of the quadrature-axis voltage feedback coefficient is as follows:

[0111]

[0112] In the formula, K Vq represents the quadrature-axis voltage feedback coefficient, K a is a constant greater than 0, K b , K d are both constants less than 0, K c , K e are restricted between 0 and 1, i q represents the quadrature-axis component current, P e represents the active power, and U qIndicates the quadrature-axis component voltage. Among them, the value of the quadrature-axis component current is less than zero. When the absolute value of the quadrature-axis component current is larger, it indicates that the reactive power output of the virtual synchronous machine is larger. Since the direct-axis voltage and the quadrature-axis voltage are greater than zero, according to the active power calculation formula, the smaller the direct-axis (d-axis) current, the greater the risk of active power reverse absorption. Therefore, increasing the quadrature-axis voltage feedback coefficient of the virtual synchronous machine can better suppress active power reverse absorption. When the active power is less than zero, that is, the virtual synchronous machine absorbs active power, the constant K c will increase with the increase of the absolute value of the active power, and the feedback coefficient will also increase with the increase of active power reverse absorption. When the quadrature-axis voltage is less than zero, the smaller the quadrature-axis voltage meter, the greater the instability risk of the virtual synchronous machine and the external network synchronous machine in the voltage source mode. By increasing the feedback coefficient to suppress the decrease of the quadrature-axis voltage, the stability of the virtual synchronous machine is enhanced. After calculating the quadrature-axis voltage feedback coefficient of the virtual synchronous machine in the embodiment of the present application, the reference value of the active power loop of the virtual synchronous machine can be updated according to the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to obtain an updated reference value. The control equation of the active power loop is updated according to the updated reference value, so as to adjust the frequency and power angle of the virtual synchronous machine to obtain a second control strategy.

[0113] One of the technical solutions in the above technical solutions has the following advantages or beneficial effects: Through the second control strategy, the embodiment of the present application can adaptively adjust the feedback parameters according to the instability risk, thereby improving the power angle stability of the virtual synchronous machine and the external network synchronous machine in the voltage source mode and suppressing the active power reverse absorption of the virtual synchronous machine.

[0114] Next, in combination with specific application examples, the solution of the embodiment of the present application will be introduced and described in detail:

[0115] The embodiment of the present application can be applied to the power grid technology field and is applicable to virtual synchronous machine controlled converter equipment. Please refer to Figure 2 , the embodiment of the present application applies the power angle stability enhancement strategy of the VSG controlled converter equipment. Please refer to Figure 3 , Figure 3 In, the number of synchronous machines in systems G1, G2, G3, G4, and G5 is 4, 1, 3, 2, and 4 respectively, and the rated capacity and active power of each synchronous machine are 360 MVA and 288 MW respectively. Virtual synchronous machines of 864 MW and 576 MW are connected to buses F and R respectively. The fault setting is as follows: A three-phase short-circuit fault occurs on the K side of a certain line in section KL at 0.1 s and lasts for 0.15 s, and then the circuit breakers on both sides of the line trip. Three simulation experimental groups are set up. Experimental group 1: The VSG does not use the control of the embodiment of the present application. Experimental group 2: The VSG adopts the power angle stability enhancement strategy applicable to the VSG controlled converter equipment of the embodiment of the present application. Please refer to the simulation results Figure 4 , Figure 5 and Figure 6 . FromFigure 4 and Figure 5 During the 0 - 0.6s simulation period of Figure 5 , it can be seen that the control strategy proposed in the embodiment of the present application improves the power angle stability between the VSG and the synchronous machine under the current saturation mode. From Figure 4 and Figure 5 During the 0.6s - 3s simulation period of Figure 5 , it can be seen that the control strategy proposed in the embodiment of the present application improves the power angle stability between the VSG and the synchronous machine under the voltage source mode. From Figure 6 It can be seen that the control strategy proposed in the embodiment of the present application can suppress the reverse absorption of active power by the VSG.

[0116] Please refer to Figure 7 , the embodiment of the present application also provides a power system power angle stability enhancement system, which can implement the above - mentioned power system power angle stability enhancement method. The system includes:

[0117] The first module 701 is used to obtain the current saturation mode data and voltage source mode data of the power system;

[0118] The second module 702 is used to adjust the damping coefficient of the virtual synchronous generator according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous generator, so as to control the power angle difference between the virtual synchronous generator and the external network synchronous machine;

[0119] The third module 703 is used to adjust the quadrature - axis voltage feedback coefficient of the virtual synchronous generator according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous generator according to the quadrature - axis voltage feedback coefficient of the virtual synchronous generator;

[0120] The fourth module 704 is used to perform control processing on the power system according to the first control strategy and the second control strategy.

[0121] It can be understood that the content in the above - mentioned method embodiment is applicable to the system embodiment of the present application. The functions specifically implemented by the system embodiment of the present application are the same as those of the above - mentioned method embodiment, and the beneficial effects achieved are also the same as those of the above - mentioned method embodiment.

[0122] The embodiment of the present application also provides an electronic device. The electronic device includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements the above - mentioned power system power angle stability enhancement method. The electronic device can be any intelligent terminal including a tablet computer, an in - vehicle computer, etc.

[0123] It can be understood that the content in the above method embodiments is applicable to the device embodiments of the present invention. The functions specifically implemented by the device embodiments of the present invention are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0124] Please refer to Figure 8 , Figure 8 which schematically shows the hardware structure of an electronic device according to another embodiment. The electronic device includes:

[0125] A processor 801, which can be implemented in ways such as a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided by the embodiments of the present application;

[0126] A memory 802, which can be implemented in forms such as a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 802 can store an operating system and other application programs. When implementing the technical solutions provided by the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory 802 and are called by the processor 801 to execute the power system power angle stability enhancement method of the embodiments of the present application;

[0127] An input / output interface 803, which is used to implement information input and output;

[0128] A communication interface 804, which is used to implement communication interaction between this device and other devices, and can implement communication through a wired method (such as USB, network cable, etc.) or through a wireless method (such as a mobile network, WIFI, Bluetooth, etc.);

[0129] A bus 805, which transmits information between various components of the device (such as the processor 801, the memory 802, the input / output interface 803, and the communication interface 804);

[0130] Among them, the processor 801, the memory 802, the input / output interface 803, and the communication interface 804 are communicatively connected to each other inside the device through the bus 805.

[0131] The embodiments of the present application also provide a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the above-mentioned power system power angle stability enhancement method.

[0132] It can be understood that the content in the above method embodiments is applicable to this storage medium embodiment. The functions specifically implemented by this storage medium embodiment are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those of the above method embodiments.

[0133] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory can include high-speed random access memory, and can also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory optionally includes a memory remotely disposed relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above network include but are not limited to the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0134] A power system power angle stability enhancement method, system, device, and medium provided by an embodiment of the present application. This solution obtains the current saturation mode data and voltage source mode data of the power system, adjusts the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy, and can adjust the damping coefficient of the virtual synchronous machine based on the current saturation mode data to reduce the power angle difference, thereby improving the power angle stability between the virtual synchronous machine and the external network synchronous machine under the current saturation mode. In addition, this solution adjusts the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy, which can adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to reduce the instability risk between the virtual synchronous machine and the external network synchronous machine, and improve the power angle stability between the virtual synchronous machine and the external network synchronous machine under the voltage source mode.

[0135] The embodiments described in the embodiments of the present application are for more clearly explaining the technical solutions of the embodiments of the present application, and do not constitute a limitation to the technical solutions provided by the embodiments of the present application. Those skilled in the art know that with the evolution of technology and the emergence of new application scenarios, the technical solutions provided by the embodiments of the present application are equally applicable to similar technical problems.

[0136] Those skilled in the art can understand that the technical solutions shown in the figures do not constitute a limitation to the embodiments of the present application, and may include more or fewer steps than shown in the figures, or combine certain steps, or different steps.

[0137] The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, that is, they may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0138] Those of ordinary skill in the art can understand that all or some of the steps in the methods disclosed above, and the functional modules / units in systems and devices, can be implemented as software, firmware, hardware, and appropriate combinations thereof.

[0139] As used in the specification of this application and the above-mentioned drawings, the terms "first", "second", "third", "fourth", etc. (if any) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0140] It should be understood that in this application, "at least one (item)" means one or more, and "a plurality" means two or more. "And / or" is used to describe the association relationship of associated objects and indicates that three relationships can exist. For example, "A and / or B" can mean: only A exists, only B exists, and both A and B exist at the same time. Among them, A and B can be singular or plural. The character " / " generally means that the associated objects before and after are in an "or" relationship. "At least one (one) of the following" or its similar expression means any combination of these items, including any combination of single items (ones) or plural items (ones). For example, at least one (one) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0141] In the several embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the above-mentioned unit division is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling, direct coupling, or communication connection to each other can be through some interfaces. The indirect coupling or communication connection of systems or units can be in electrical, mechanical, or other forms.

[0142] The units described above as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0143] In addition, each functional unit in various embodiments of the present application may be integrated in a processing unit, may exist separately as individual physical units, or two or more units may be integrated in one unit. The above-mentioned integrated units may be implemented in the form of hardware or in the form of software functional units.

[0144] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present application. The aforementioned storage medium includes: various media that can store programs such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs.

[0145] The preferred embodiments of the embodiments of the present application have been described above with reference to the accompanying drawings, but this does not limit the scope of rights of the embodiments of the present application. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the embodiments of the present application shall be within the scope of rights of the embodiments of the present application.

Claims

1. A method for enhancing power system power angle stability, characterized in that: The method comprises the following steps: Acquire current saturation mode data and voltage source mode data of the power system; The damping coefficient of the virtual synchronous machine is adjusted according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous machine, thereby controlling the power angle difference between the virtual synchronous machine and the external network synchronous machine; The quadrature-axis voltage feedback coefficient of the virtual synchronous machine is adjusted according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous machine according to the quadrature-axis voltage feedback coefficient of the virtual synchronous machine; The power system is controlled according to the first control strategy and the second control strategy.

2. The method according to claim 1, characterized in that The method of obtaining current saturation mode data of the power system comprises the following steps: Collect the voltage amplitude on the high-voltage side of the step-up transformer in the grid-connected converter; The low-voltage side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode is collected and processed to obtain the external grid frequency; Performing active power ring calculation processing on the virtual synchronous machine to obtain the virtual synchronous machine frequency; The current saturation mode data is obtained according to the high-voltage side voltage amplitude, the external power grid frequency and the virtual synchronous machine frequency.

3. The method according to claim 2, characterized in that The collecting and processing of the low-voltage side frequency of the step-up transformer in the virtual synchronous machine in the current saturation mode to obtain the external grid frequency includes the following steps: The three-phase voltage vector of the low-voltage side of the boost transformer of the virtual synchronous machine is acquired by a signal acquisition system; The three-phase voltage vector is input into a phase-locked loop, and the external power grid frequency is obtained through the output of the phase-locked loop.

4. The method according to claim 1, characterized in that The voltage source mode data of the power system comprises the following steps: Perform quadrature-axis component acquisition and processing on the output current of the virtual synchronous machine to obtain quadrature-axis component current; Collecting and processing the active power of the virtual synchronous machine to obtain the active power; Performing quadrature-axis component acquisition processing on the low-voltage side node voltage of the step-up transformer in the virtual synchronous machine to obtain a quadrature-axis component voltage; The voltage source mode data is obtained according to the quadrature-axis component current, the active power and the quadrature-axis component voltage.

5. The method according to claim 1, characterized in that The adjusting process of the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy comprises the following steps: According to the current saturation mode data, the high voltage side voltage amplitude, the external grid frequency and the virtual synchronous machine frequency are obtained; When the voltage amplitude on the high-voltage side is greater than a preset threshold, the damping coefficient of the virtual synchronous machine is set to a steady-state damping coefficient; When the voltage amplitude on the high-voltage side is less than or equal to the preset threshold, the damping coefficient of the virtual synchronous machine is calculated according to the external power grid frequency and the virtual synchronous machine frequency; The power angle acceleration of the virtual synchronous machine is controlled according to the damping coefficient of the virtual synchronous machine to determine the first control strategy.

6. The method according to claim 5, characterized in that The step of calculating the damping coefficient of the virtual synchronous machine according to the external power grid frequency and the virtual synchronous machine frequency comprises the following steps: Subtract the external power grid frequency from the virtual synchronous machine frequency to obtain a frequency difference; The frequency difference is multiplied by a preset first constant, and the multiplication result is added to the steady-state damping coefficient to obtain the damping coefficient of the virtual synchronous machine.

7. The method according to claim 1, characterized in that The adjusting process of the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy comprises the following steps: Calculate the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data; updating the reference value of the active power loop of the virtual synchronous machine by using the quadrature-axis voltage feedback coefficient of the virtual synchronous machine to obtain an updated reference value; The control equation of the active power loop is updated according to the updated reference value, thereby adjusting the frequency and power angle of the virtual synchronous machine to obtain the second control strategy.

8. A power system power angle stability enhancement system, characterized in that: The system comprises: The first module is used to obtain current saturation mode data and voltage source mode data of the power system; The second module is used to adjust the damping coefficient of the virtual synchronous machine according to the current saturation mode data to obtain a first control strategy; the first control strategy is used to adjust the damping coefficient of the virtual synchronous machine, thereby controlling the power angle difference between the virtual synchronous machine and the external network synchronous machine; The third module is used to adjust the quadrature-axis voltage feedback coefficient of the virtual synchronous machine according to the voltage source mode data to obtain a second control strategy; the second control strategy is used to adjust the frequency and power angle of the virtual synchronous machine according to the quadrature-axis voltage feedback coefficient of the virtual synchronous machine; The fourth module is used to control the power system according to the first control strategy and the second control strategy.

9. An electronic device, characterized in that: The electronic device comprises a memory and a processor, the memory stores a computer program, and the processor implements the method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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