A distributed synchronous condenser excitation transient stability method and device

Abstract

The present invention provides a method and device for the excitation transient stability of a distributed synchronous condenser. The method for the excitation transient stability of the distributed synchronous condenser includes: determining whether a system fault occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage; when a system fault occurs, determining a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser; and modifying the original machine terminal voltage according to the control quantity. The present invention has an obvious effect of maintaining the rotor stability during both the deceleration and acceleration processes of the synchronous condenser, can effectively prevent the power of the synchronous condenser from entering an oscillating or divergent state, thereby improving the transient stability of the synchronous condenser and being beneficial to the recovery of the transient fault of the new energy power station system.

Description

Technical Field

[0001] This application belongs to the technical field of power system automation, and particularly relates to a method and device for transient stability of distributed synchronous condenser excitation. Background Art

[0002] Due to various factors, there is a lack of supporting power sources in the vicinity of large-scale new energy bases, resulting in insufficient short-circuit ratio indicators for multiple new energy power stations and relatively serious limitations in power transmission capacity. In recent years, deploying distributed synchronous condensers in new energy power stations to improve the short-circuit ratio of multiple new energy power stations has become an effective measure. More and more new energy power stations are deploying distributed synchronous condensers to enhance the voltage support ability of new energy power stations for the power grid.

[0003] It can be understood that control and protection strategies such as high and low voltage ride-through, power recovery, or emergency disconnection during and after faults in wind power and photovoltaic equipment of new energy power stations will affect the transient stability of the system. As a special synchronous motor, a distributed synchronous condenser has an inertia response characteristic, which determines that the synchronous condenser will also participate in power disturbances during the transient process of new energy power stations. That is, when the system has continuous active power surplus or active power deficit due to faults, the synchronous condenser may become unstable, deteriorating the safety and stability of new energy power stations. Summary of the Invention

[0004] In the prior art, the research on installing distributed synchronous condensers in new energy power stations mainly focuses on voltage stability, and there is less research on power angle stability. In addition, although there have been relevant studies on enhancing the transient stability characteristics of conventional synchronous generator excitation control systems by superimposing additional control strategies, the synchronous condenser is different from the conventional synchronous generator. On the one hand, the application scenarios and the stability problems to be solved are different. The synchronous condenser mainly solves the power angle stability problem under cascading faults in new energy power stations. On the other hand, the synchronous condenser is a motor, and its active power is almost zero under stable operating conditions. During the disturbance process, the active power of the synchronous condenser oscillates between positive and negative values. Therefore, the transient stability additional control criterion is also different from that of conventional synchronous generators.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for transient stability of distributed synchronous condenser excitation, including:

[0007] Judging whether a system fault occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage;

[0008] When a system fault occurs, determining the control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser;

[0009] Modify the original machine terminal voltage according to the control quantity.

[0010] According to an embodiment of the present invention, determining whether a system fails according to the active power, rotational speed, and original machine terminal voltage of the distributed synchronous condenser includes:

[0011] Determine whether the system fails according to the change rate of the active power and the change amount of the original machine terminal voltage.

[0012] According to an embodiment of the present invention, determining whether the system fails according to the change rate of the active power and the change amount of the original machine terminal voltage includes:

[0013] When the change rate is greater than a first preset threshold and the change amount is greater than a second preset threshold, it is determined that the system fails.

[0014] According to an embodiment of the present invention, determining the control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser includes:

[0015] When a first condition or a second condition is satisfied, determine that the control quantity is a first change amount;

[0016] Wherein, the first change amount is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

[0017] According to an embodiment of the present invention, determining the control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser further includes:

[0018] When a third condition or a fourth condition is satisfied, determine that the control quantity is a second change amount;

[0019] Wherein, the second change amount is less than 0, the third condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is less than 1.

[0020] According to an embodiment of the present invention, after modifying the original machine terminal voltage according to the control quantity, it further includes:

[0021] Determine a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser;

[0022] When the stop modification condition is satisfied, in the excitation transient stability method of the distributed synchronous condenser, modify the current terminal voltage of the distributed synchronous condenser to the original machine terminal voltage.

[0023] According to an embodiment of the present invention, the stop modification condition includes:

[0024] The number of times the rotational speed exceeds the rated rotational speed is not less than a predetermined number of times.

[0025] In a second aspect, the present invention provides a distributed synchronous condenser excitation transient stability device, and the device includes:

[0026] A fault judgment module, configured to judge whether a system fails according to the active power of the distributed synchronous condenser and the voltage at the original machine terminal;

[0027] A control quantity determination module, configured to determine a control quantity of the voltage at the original machine terminal according to the active power and the rotational speed of the distributed synchronous condenser when the system fails;

[0028] A machine terminal voltage modification module, configured to modify the voltage at the original machine terminal according to the control quantity.

[0029] According to an embodiment of the present invention, the fault judgment module includes:

[0030] A fault judgment unit, configured to judge whether a system fails according to the change rate of the active power and the change amount of the voltage at the original machine terminal.

[0031] According to an embodiment of the present invention, the fault judgment unit includes:

[0032] A fault judgment subunit, configured to judge that the system fails when the change rate is greater than a first preset threshold and the change amount is greater than a second preset threshold.

[0033] According to an embodiment of the present invention, the control quantity determination module includes:

[0034] A first control quantity determination unit, configured to determine the control quantity as a first change amount when a first condition or a second condition is satisfied;

[0035] Wherein, the first change amount is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

[0036] According to an embodiment of the present invention, the control quantity determination module further includes:

[0037] A second control quantity determination unit, configured to determine the control quantity as a second change amount when a third condition or a fourth condition is satisfied;

[0038] Wherein, the second variation is less than 0, the third condition is that the per-unit value of the active power is less than 0, and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0, and the per-unit value of the rotational speed is less than 1.

[0039] According to an embodiment of the present invention, the distributed synchronous condenser excitation transient stability device further includes:

[0040] A stop intervention condition determination module, configured to determine a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser;

[0041] A terminal voltage restoration module, configured to modify the current terminal voltage of the distributed synchronous condenser to the original terminal voltage when the stop modification condition is satisfied.

[0042] According to an embodiment of the present invention, the stop modification condition includes:

[0043] The number of times the rotational speed exceeds the rated rotational speed is not less than a predetermined number of times.

[0044] In a third aspect, the present invention provides a computer program product, including a computer program / instructions, and when the computer program / instructions are executed by a processor, the steps of the distributed synchronous condenser excitation transient stability method are implemented.

[0045] In a fourth aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the steps of the distributed synchronous condenser excitation transient stability method are implemented.

[0046] In a fifth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the distributed synchronous condenser excitation transient stability method are implemented.

[0047] As can be seen from the above description, the embodiments of the present invention provide a distributed synchronous condenser excitation transient stability method and device. The corresponding method includes: first, determining whether a system failure occurs according to the active power of the distributed synchronous condenser and the original terminal voltage; then, when a system failure occurs, determining a control amount of the original terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser; and finally, modifying the original terminal voltage according to the control amount.

[0048] The present invention has an obvious effect of maintaining rotor stability during both the deceleration and acceleration processes of the synchronous condenser, can effectively prevent the power of the synchronous condenser from entering an oscillating or divergent state, thereby improving the transient stability of the synchronous condenser and facilitating the recovery of transient faults in the new energy power station system. Description of the Drawings

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for describing the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0050] Figure 1 It is a schematic flow chart of the distributed synchronous condenser excitation transient stability method in the embodiments of the present invention;

[0051] Figure 2 It is a schematic flow chart of step 100 in the embodiments of the present invention;

[0052] Figure 3 It is a schematic diagram of the distributed synchronous condenser excitation control principle in the embodiments of the present invention;

[0053] Figure 4 It is a schematic flow chart of step 101 in the embodiments of the present invention;

[0054] Figure 5 It is a schematic flow chart of one of the steps 200 in the embodiments of the present invention;

[0055] Figure 6 It is another schematic flow chart of step 200 in the embodiments of the present invention;

[0056] Figure 7 It is another schematic flow chart of the distributed synchronous condenser excitation transient stability method in the embodiments of the present invention;

[0057] Figure 8 It is a logical mind map of the distributed synchronous condenser excitation transient stability method in the specific embodiments of the present invention;

[0058] Figure 9 It is a primary system diagram of the simulation example in the specific embodiments of the present invention;

[0059] Figure 10 It is a comparative oscillogram of the on / off of the excitation transient stability when the synchronous condenser decelerates and becomes unstable due to a fault in the specific embodiments of the present invention;

[0060] Figure 11 It is the oscillogram of the output of the excitation transient stability additional control function when the synchronous condenser decelerates and becomes unstable due to a fault in the specific embodiments of the present invention Figure 1 ;

[0061] Figure 12 It is the oscillogram of the output of the excitation transient stability additional control function when the synchronous condenser decelerates and becomes unstable due to a fault in the specific embodiments of the present invention Figure 2 ;

[0062] Figure 13 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser decelerates and becomes unstable due to a fault in the specific embodiment of the present invention Figure 3 ;

[0063] Figure 14 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser decelerates and becomes unstable due to a fault in the specific embodiment of the present invention Figure 4 ;

[0064] Figure 15 Comparison oscillogram of the excitation transient stability when the synchronous condenser accelerates during a fault in the specific embodiment of the present invention;

[0065] Figure 16 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser accelerates due to a fault in the specific embodiment of the present invention Figure 1 ;

[0066] Figure 17 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser accelerates due to a fault in the specific embodiment of the present invention Figure 2 ;

[0067] Figure 18 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser accelerates due to a fault in the specific embodiment of the present invention Figure 3 ;

[0068] Figure 19 Oscillogram of the output of the additional excitation transient stability control function when the synchronous condenser accelerates due to a fault in the specific embodiment of the present invention Figure 4 ;

[0069] Figure 20 Schematic diagram of the excitation transient stability device of the distributed synchronous condenser in the specific embodiment of the present invention;

[0070] Figure 21 Block diagram of the fault judgment module 10 in the embodiment of the present invention Figure 1 ;

[0071] Figure 22 Block diagram of the fault judgment unit 101 in the embodiment of the present invention;

[0072] Figure 23 Block diagram of the control quantity determination module 20 in the embodiment of the present invention Figure 1 ;

[0073] Figure 24 Block diagram of the control quantity determination module 20 in the embodiment of the present invention Figure 1 ;

[0074] Figure 25The block diagram of the fault judgment module 10 in the embodiments of the present invention Figure 2 。

[0075] Figure 26 The structural schematic diagram of the electronic device in the embodiments of the present invention. Detailed implementation manners

[0076] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0077] Those skilled in the art should understand that the embodiments of the present invention may be provided as a method, a system, or a computer program product. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0078] It should be noted that the terms "including" and "having" in the description and claims of this application and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily limit 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.

[0079] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0080] At present, the research on adding distributed synchronous condensers to new energy power stations mainly focuses on voltage stability, and there is less research on power angle stability. Proposing a control optimization strategy for the excitation system of distributed synchronous condensers is an economical and effective means to improve the transient stability of synchronous condensers, and is of great significance to the safe and stable operation of the entire new energy power station.

[0081] There have been relevant studies on improving the transient stability characteristics of conventional synchronous generators by superimposing additional control strategies in the excitation control system of conventional synchronous generators. However, the synchronous condenser is different from the conventional synchronous generator. Specifically, on the one hand, their application scenarios and the stability problems to be solved are different. The synchronous condenser mainly solves the power angle stability problem under cascading faults in new energy substations. On the other hand, the synchronous condenser is a motor. Under stable operating conditions, the active power of the synchronous condenser is almost zero. During the disturbance process, the active power of the synchronous condenser oscillates between positive and negative values. Therefore, the transient stability additional control criterion is also different from that of the conventional synchronous generator.

[0082] Based on the above technical pain points, an embodiment of the present invention provides a specific implementation manner of a distributed synchronous condenser excitation transient stability method. Refer to Figure 1 , and the method specifically includes the following content:

[0083] Step 100: Determine whether a system fault occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage.

[0084] Step 200: When a system fault occurs, determine the control amount of the original machine terminal voltage according to the active power and the speed of the distributed synchronous condenser.

[0085] Step 300: Modify the original machine terminal voltage according to the control amount.

[0086] As can be seen from the above description, an embodiment of the present invention provides a distributed synchronous condenser excitation transient stability method. This method identifies the operating state of the synchronous condenser by collecting information such as the machine terminal voltage, active power, and speed of the distributed synchronous condenser, and superimposes the machine terminal voltage control amount in the excitation control system to improve the transient stability support ability of the distributed synchronous condenser and improve the power angle stability characteristics under complex faults in new energy substations.

[0087] The present invention has an obvious effect of maintaining the rotor stability during both the deceleration and acceleration processes of the synchronous condenser, which can effectively prevent the power of the synchronous condenser from entering an oscillating or divergent state, thereby improving the transient stability of the synchronous condenser and being beneficial to the recovery of transient faults in the new energy substation system.

[0088] In the power grid, the electric power supplied by the power source to the load is divided into active power and reactive power. The function of active power is to convert electrical energy into other forms of energy. The function of reactive power is to establish and maintain a magnetic field in electrical equipment and maintain voltage balance. A synchronous condenser is a reactive power compensation device, which is a synchronous motor that supplies or absorbs reactive power to the power system. Essentially, a synchronous condenser is a synchronous motor in a special operating state. When applied to the power system, it can automatically increase reactive power output when the grid voltage drops. When the grid voltage rises, the synchronous condenser absorbs reactive power to maintain the voltage, improve the stability of the power system, and improve the power supply quality of the system. A synchronous motor operates in the motor state, without a mechanical load or a prime mover, and only supplies or absorbs reactive power to the power system, also known as a synchronous compensator. It is used to improve the power factor of the power grid and maintain the grid voltage level.

[0089] It should be noted that the original machine terminal voltage in step 100 refers to the machine terminal voltage before the excitation transient stability method of the distributed synchronous condenser provided by this application intervenes in the distributed synchronous condenser.

[0090] According to an embodiment of the present invention, refer to Figure 2 , step 100 includes:

[0091] Step 101: Determine whether a system fault occurs according to the change rate of the active power and the change amount of the original machine terminal voltage.

[0092] The excitation control system of the excitation regulator of the distributed synchronous condenser is as Figure 3 shown (constant voltage control mode), U ref is the given value of the machine terminal voltage, U t is the per-unit value of the machine terminal voltage (the ratio of the actual value of the machine terminal voltage to the rated machine terminal voltage), PID is the transfer function, and U f is the excitation voltage. The working principle of the synchronous condenser is: the excitation regulator of the synchronous condenser determines U t , and compares it with U ref , after obtaining the deviation amount, it is adjusted through the PID link, and by adjusting U f , the U t of the synchronous condenser is made equal to U ref , realizing the closed-loop regulation of the excitation control system.

[0093] According to an embodiment of the present invention, refer to Figure 4 , step 101 includes:

[0094] Step 1011: When the change rate is greater than the first preset threshold and the change amount is greater than the second preset threshold, determine that a system fault occurs.

[0095] (1) Rate of change ΔV of per-unit value P of active power P > A (the first preset threshold); (2) Drop amount ΔU of per-unit value U of terminal voltage t t > B (the second preset threshold); When the above two criteria are both met, it is determined that a system fault has occurred. Then, the distributed synchronous condenser excitation transient stability method provided by the embodiments of the present invention starts to intervene in the synchronous condenser. It should be noted that the per-unit value mentioned above refers to the ratio of the actual value of the active power of the distributed synchronous condenser to its rated value.

[0096] According to an embodiment of the present invention, referring to Figure 5

[0097] Step 201: When the first condition or the second condition is satisfied, determine that the control quantity is the first change quantity;

[0098] Wherein, the first change quantity is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

[0099] Specifically, if the per-unit value P of the active power of the distributed synchronous condenser satisfies P ≥ 0 and w - 1 ≥ 0 (w is the per-unit value of the rotational speed of the distributed synchronous condenser), or P < 0 and w - 1 < 0, ΔU r (the control quantity introduced at the superimposition point of U ref and U t ) output is ΔU r1 (ΔU r1 is a positive value). Similar to the parameter P, the per-unit value of the rotational speed here is the ratio of the actual value of the rotational speed of the distributed synchronous condenser to its rated value.

[0100] According to an embodiment of the present invention, referring to Figure 6

[0101] Step 202: When the third condition or the fourth condition is satisfied, determine that the control quantity is the second change quantity;

[0102] Wherein, the second change quantity is less than 0, the third condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is less than 1.

[0103] If the per-unit value P of the active power of the distributed synchronous condenser satisfies P < 0 and w - 1 ≥ 0, or the per-unit value P of the active power of the synchronous condenser satisfies P ≥ 0 and w - 1 < 0, ΔU r output is ΔU r2 (ΔUr2 is negative).

[0104] According to an embodiment of the present invention, referring to Figure 7 , in the method for transient stability of the excitation of a distributed synchronous condenser, after step 300, it further includes:

[0105] Step 400: Determine a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser;

[0106] Step 500: When the stop modification condition is satisfied, modify the current terminal voltage of the distributed synchronous condenser to the original terminal voltage.

[0107] According to an embodiment of the present invention, the number of times that the rotational speed in step 400 exceeds the rated rotational speed is not less than a predetermined number of times.

[0108] During a fault, the per-unit value w of the rotational speed of the distributed synchronous condenser swings above and below the rated rotational speed. When the method for transient stability of the excitation of the distributed synchronous condenser provided by the embodiment of the present application intervenes in the distributed synchronous condenser, and the total number of sign changes of w - 1 (the per-unit value w of the rotational speed is positive above the rated rotational speed and negative below the rated rotational speed) ≥ N1 (predetermined number of times), △U r outputs from △U r1 or △U r2 becomes 0, and the additional control for excitation transient stability is turned off.

[0109] As can be seen from the above description, the embodiment of the present invention provides a method for transient stability of the excitation of a distributed synchronous condenser, and the method includes:

[0110] The present invention introduces a control quantity △U ref at the superposition point of the given value U t of the terminal voltage and the per-unit value U r of the terminal voltage, uses the per-unit value P of the active power, the per-unit value w of the rotational speed, and the per-unit value U t of the terminal voltage collected and calculated by the excitation regulator to make a logical judgment, and changes the output △U r , thereby realizing the transient stability control of the distributed synchronous condenser and improving the transient stability characteristics of the new energy power station through the excitation system of the synchronous condenser.

[0111] Specifically, during the occurrence, duration, and recovery of a system fault, the action criteria for the per-unit value P of the active power, the per-unit value w of the rotational speed, and the per-unit value U t of the additional control for excitation transient stability of the distributed synchronous condenser, and the output value of △U r are as follows:

[0112] 1. Before the occurrence of a system fault, the additional control for excitation transient stability is not started, and △Ur The output is 0.

[0113] 2. (1) The rate of change △V of the per-unit value P of the active power P >A; (2) The drop amount △U of the per-unit value U of the terminal voltage t ; When the above two criteria are satisfied simultaneously, the additional control for excitation transient stability is started. t >B; When the above two criteria are satisfied simultaneously, the additional control for excitation transient stability is started.

[0114] 3. If P≥0 and ω-1≥0, or P<0 and ω-1<0, △U r The output is △U r1 (△U r1 is a positive value).

[0115] 4. If P<0 and ω-1≥0, or P≥0 and ω-1<0, △U r The output is △U r2 (△U r2 is a negative value).

[0116] 5. During the fault process, the per-unit value ω of the speed of the synchronous condenser swings above and below the rated speed. When the additional control for excitation transient stability is started and the total number of sign changes of ω-1≥N1, △U r The output changes from △U r1 or △U r2 to 0, and the additional control for excitation transient stability is turned off.

[0117] The present invention has an obvious effect of maintaining the rotor stability during the deceleration and acceleration processes of the synchronous condenser, can effectively prevent the power of the synchronous condenser from entering the oscillation or divergence state, improves the transient stability of the synchronous condenser, and is beneficial to the recovery of the transient fault of the new energy power station system.

[0118] In a specific embodiment, referring to Figure 8 , the present invention also provides a specific embodiment in the method for excitation transient stability of the distributed synchronous condenser.

[0119] Referring to Figure 9 , the simplified simulation system corresponding to the method for excitation transient stability of the distributed synchronous condenser provided by this specific embodiment is a wind turbine generator and a distributed synchronous condenser connected to an infinite system through their respective step-up transformers and a single-circuit transmission line. Among them, the output power of the wind turbine generator is 232.5 MW, including the high and low voltage ride-through control functions and the logic of frequency-loss protection tripping; the capacity of the synchronous condenser is 50 MVar, and the excitation system is of the self-excited type.

[0120] The fault type set in the simulation is that after a single-phase instantaneous ground short-circuit fault occurs on the transmission line, the circuit breaker trips and then recloses successfully. Among them, the duration of the "single-phase ground short-circuit fault" is 0.1 s. After 0.1 s, the circuit breaker trips, and after another 0.3 s, the circuit breaker recloses successfully.

[0121] The setting values of the excitation transient stability supplementary control are as follows:

[0122] The PID is where s is the differential operator.

[0123] A is 1 p.u. / s; B is 0.2 p.u.; △U r1 is 0.2 p.u.; △U r2 is -0.5 p.u.; N1 is 5 times.

[0124] Simulate the same system fault, compare the enabling and disabling of the excitation transient stability supplementary control function of the distributed synchronous condenser, and the transient regulation process of the distributed synchronous condenser during the occurrence and evolution of the system fault.

[0125] (1) Scenario 1: After a single-phase instantaneous short-circuit fault occurs, the circuit breaker trips and then recloses successfully, and the frequency loss protection shutdown logic of the doubly-fed wind turbine is added. Among them, the duration of the "single-phase ground fault" is 0.1 s. After 0.1 s, the circuit breaker trips, and after another 0.3 s, the circuit breaker recloses successfully; when the frequency f of the stator side of the wind turbine is > 51.5 Hz or f < 48.5 Hz, the frequency loss protection of the wind turbine acts to shut down.

[0126] Enable and disable the excitation transient stability supplementary control function of the distributed synchronous condenser, and the oscillogram comparison is as Figure 10 shown. Among them, Condition 1 represents the case where the transient stability supplementary control function is not enabled, and Condition 2 represents the case where this function is enabled.

[0127] Among them, when the excitation transient stability supplementary control function of the distributed synchronous condenser is enabled, the output waveform of the excitation supplementary control is as Figures 11 to 14 shown.

[0128] It can be obtained from Figure 10 that this fault situation will cause the synchronous condenser to decelerate and become unstable, while after enabling the excitation transient stability supplementary control function, the synchronous condenser can return to the normal operating state. It can be obtained from Figures 11 to 14 that during the process of the excitation transient stability supplementary control function taking effect, the change of its supplementary control output depends on the positive and negative of the active power and speed of the synchronous condenser, and the output time depends on the positive and negative displacement times of the difference between the speed and the rated value. When the number of times reaches 5 times, the supplementary control output function is turned off, which is consistent with the theoretical principle logic of the designed function of the distributed synchronous condenser.

[0129] (2) Scenario 2: After a single-phase instantaneous short-circuit fault occurs, the circuit breaker trips, and then reclosing is successful, removing the frequency-loss protection shutdown logic of the doubly-fed fan. Among them, the duration of the "single-phase ground fault" is 0.1 s. The circuit breaker trips after 0.1 s, and then the circuit breaker recloses successfully after 0.3 s

[0130] Exit and input the additional control function for the transient stability of the distributed synchronous condenser excitation. The comparison of the oscillograms is as Figure 15 shown. Among them, condition 1 represents not inputting the additional control function for transient stability, and condition 2 represents inputting this function.

[0131] Among them, when the additional control function for the transient stability of the distributed synchronous condenser excitation is input, the output waveform of the additional control is as Figures 16 to 19 shown.

[0132] It can be obtained from Figure 15 that this fault situation will cause the synchronous condenser to accelerate to a relatively high speed level. After inputting the additional control function for the transient stability of the excitation, the overspeed of the synchronous condenser rotor can be significantly suppressed. Similar to scenario (1), it can be obtained from Figures 16 to 19 that during the process of the additional control function for the transient stability of the excitation taking effect, the change in its additional control output depends on the positive and negative of the active power and speed of the synchronous condenser. The time of the output depends on the number of positive and negative displacements of the difference between the speed and the rated value. When the number reaches 5 times, the additional control output function is turned off, which is consistent with the theoretical principle logic of the designed function of the distributed synchronous condenser.

[0133] Based on the same inventive concept, the embodiment of the present application also provides a distributed synchronous condenser excitation transient stability device, which can be used to implement the method described in the above embodiment, as in the following embodiment. Since the principle of solving problems by the distributed synchronous condenser excitation transient stability device is similar to that of the distributed synchronous condenser excitation transient stability method, the implementation of the distributed synchronous condenser excitation transient stability device can refer to the implementation of the distributed synchronous condenser excitation transient stability method, and the repeated parts will not be described again. Hereinafter, the term "unit" or "module" may be a combination of software and / or hardware that can implement a predetermined function. Although the system described in the following embodiments is preferably implemented in software, the implementation in hardware, or a combination of software and hardware, is also possible and contemplated.

[0134] The embodiment of the present invention provides a specific implementation manner of a distributed synchronous condenser excitation transient stability device capable of implementing the distributed synchronous condenser excitation transient stability method. Refer to Figure 20 , and the distributed synchronous condenser excitation transient stability device specifically includes the following contents:

[0135] A fault judgment module 10, configured to judge whether a system fault occurs according to the active power of the distributed synchronous condenser and the voltage at the original machine terminal;

[0136] A control quantity determination module 20, configured to determine a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser when a fault occurs in the system;

[0137] A machine terminal voltage modification module 30, configured to modify the original machine terminal voltage according to the control quantity.

[0138] According to an embodiment of the present invention, referring to Figure 21 , the fault determination module 10 includes:

[0139] A fault determination unit 101, configured to determine whether a fault occurs in the system according to the change rate of the active power and the change amount of the original machine terminal voltage.

[0140] According to an embodiment of the present invention, referring to Figure 22 , the fault determination unit 101 includes:

[0141] A fault determination subunit 1011, configured to determine that a fault occurs in the system when the change rate is greater than a first preset threshold and the change amount is greater than a second preset threshold.

[0142] According to an embodiment of the present invention, referring to Figure 23 , the control quantity determination module 20 includes:

[0143] A first control quantity determination unit 201, configured to determine the control quantity as a first change amount when a first condition or a second condition is satisfied;

[0144] Wherein, the first change amount is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

[0145] According to an embodiment of the present invention, referring to Figure 24 , the control quantity determination module 20 further includes:

[0146] A second control quantity determination unit 202, configured to determine the control quantity as a second change amount when a third condition or a fourth condition is satisfied;

[0147] Wherein, the second change amount is less than 0, the third condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is less than 1.

[0148] According to an embodiment of the present invention, referring to Figure 25 , the distributed synchronous condenser excitation transient stability device further includes:

[0149] A stop intervention condition determination module 40, configured to determine a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser;

[0150] A terminal voltage restoration module 50, configured to modify the current terminal voltage of the distributed synchronous condenser to the original terminal voltage when the stop modification condition is satisfied.

[0151] According to an embodiment of the present invention, the stop modification condition includes:

[0152] The number of times the rotational speed exceeds the rated rotational speed is not less than a predetermined number of times.

[0153] As can be seen from the above description, an embodiment of the present invention provides a distributed synchronous condenser excitation transient stability device, which includes: first, determining whether a system failure occurs according to the active power of the distributed synchronous condenser and the original terminal voltage; then, when a system failure occurs, determining a control amount of the original terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser; and finally, modifying the original terminal voltage according to the control amount.

[0154] The present invention has an obvious effect of maintaining rotor stability during both the deceleration and acceleration processes of the synchronous condenser, can effectively prevent the power of the synchronous condenser from entering an oscillating or divergent state, thereby improving the transient stability of the synchronous condenser, and is beneficial to the recovery of transient faults in the new energy power station system.

[0155] An embodiment of the present application further provides a specific implementation manner of an electronic device capable of implementing all steps in the distributed synchronous condenser excitation transient stability method in the above embodiment. Refer to Figure 26 , and the electronic device specifically includes the following content:

[0156] A processor 1201, a memory 1202, a communication interface 1203, and a bus 1204;

[0157] Wherein, the processor 1201, the memory 1202, and the communication interface 1203 complete mutual communication through the bus 1204; the communication interface 1203 is used to implement information transmission between related devices such as server-side devices and client-side devices;

[0158] The processor 1201 is used to call a computer program in the memory 1202. When the processor executes the computer program, all steps in the distributed synchronous condenser excitation transient stability method in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0159] Step 100: Determine whether a system failure occurs according to the active power of the distributed synchronous condenser and the original terminal voltage;

[0160] Step 200: When a system failure occurs, determine a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser;

[0161] Step 300: Modify the original machine terminal voltage according to the control quantity.

[0162] An embodiment of the present application further provides a computer-readable storage medium capable of implementing all steps in the distributed synchronous condenser excitation transient stability method in the above embodiments. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, all steps in the distributed synchronous condenser excitation transient stability method in the above embodiments are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0163] Step 100: Determine whether a system failure occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage;

[0164] Step 200: When a system failure occurs, determine a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser;

[0165] Step 300: Modify the original machine terminal voltage according to the control quantity.

[0166] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program type embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0167] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the present invention to only the specific implementation manners. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the relevant technical fields can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

[0168] The specific embodiments of this specification are described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be executed in a different order from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In certain embodiments, multi-tasking and parallel processing are also possible or may be advantageous.

[0169] Although the present application provides method operation steps such as in the embodiments or flowcharts, more or fewer operation steps may be included based on routine or non-creative labor. The order of steps listed in the embodiments is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual device or client product is executed, it may be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in an environment of parallel processors or multi-threaded processing).

[0170] For the convenience of description, when describing the above device, it is divided into various modules according to functions for separate description. Of course, when implementing the embodiments of this specification, the functions of each module can be implemented in the same or multiple software and / or hardware, or the modules implementing the same function can be realized by a combination of multiple sub-modules or sub-units, etc. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there may 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 couplings or direct couplings or communication connections shown or discussed with each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0171] Those skilled in the art also know that in addition to implementing the controller in the form of pure computer-readable program code, the method steps can be logically programmed to enable the controller to be implemented in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. to achieve the same function. Therefore, such a controller can be regarded as a hardware component, and the devices included therein for implementing various functions can also be regarded as the structures within the hardware component. Or even, the devices for implementing various functions can be regarded as both software modules for implementing the method and the structures within the hardware component.

[0172] In a typical configuration, a computing device includes one or more processors (CPUs), an input / output interface, a network interface, and a memory.

[0173] The memory may include non-permanent memory in the form of computer-readable media, random access memory (RAM), and / or non-volatile memory such as read-only memory (ROM) or flash RAM. The memory is an example of computer-readable media.

[0174] Embodiments of this specification 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. Embodiments of this specification can also be practiced in a distributed computing environment 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.

[0175] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for system embodiments, since they are basically similar to method embodiments, the description is relatively simple. For related parts, reference can be made to the description of the method embodiments. In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0176] The above description is only for the embodiments of this specification and does not limit the embodiments of this specification. For those skilled in the art, various changes and modifications can be made to the embodiments of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of this specification shall be included in the scope of the claims of the embodiments of this specification.

Claims

1. A transient stability method for the excitation of a distributed synchronous condenser, characterized in that Including: Judging whether a system failure occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage; When a system failure occurs, determining a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser; Modifying the original machine terminal voltage according to the control quantity; The determining the control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser includes: When a first condition or a second condition is satisfied, determining the control quantity as a first change quantity; Wherein, the first change quantity is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

2. The distributed synchronous condenser excitation transient stability method according to claim 1, wherein The judging whether a system failure occurs according to the active power, rotational speed and original machine terminal voltage of the distributed synchronous condenser includes: Judging whether a system failure occurs according to the change rate of the active power and the change quantity of the original machine terminal voltage.

3. The transient stability method for the excitation of a distributed synchronous condenser according to claim 1, wherein The judging whether a system failure occurs according to the change rate of the active power and the change quantity of the original machine terminal voltage includes: When the change rate is greater than a first preset threshold and the change quantity is greater than a second preset threshold, judging that a system failure occurs.

4. The distributed synchronous condenser excitation transient stability method according to claim 1, characterized in that The determining the control quantity of the original machine terminal voltage according to the active power, rotational speed and the rotational speed of the distributed synchronous condenser further includes: When a third condition or a fourth condition is satisfied, determining the control quantity as a second change quantity; Wherein, the second change quantity is less than 0, the third condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is less than 1.

5. The distributed synchronous condenser excitation transient stability method according to claim 1, characterized in that After modifying the original machine terminal voltage according to the control quantity, it further includes: Determining a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser; When the stop modification condition is satisfied, modifying the current machine terminal voltage of the distributed synchronous condenser to the original machine terminal voltage.

6. The distributed synchronous condenser excitation transient stability method according to claim 5, characterized in that The stop modification condition includes: The number of times that the rotational speed exceeds the rated rotational speed is not less than a predetermined number of times.

7. A distributed synchronous condenser excitation transient stability device, characterized in that, Including: A fault judgment module, configured to judge whether a system failure occurs according to the active power of the distributed synchronous condenser and the original machine terminal voltage; A control quantity determination module, configured to determine a control quantity of the original machine terminal voltage according to the active power and the rotational speed of the distributed synchronous condenser when a system failure occurs; A machine terminal voltage modification module, configured to modify the original machine terminal voltage according to the control quantity; The control quantity determination module includes: A first control quantity determination unit, configured to determine the control quantity as a first change quantity when a first condition or a second condition is satisfied; Wherein, the first change quantity is greater than 0, the first condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is not less than 1; the second condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is less than 1.

8. The distributed synchronous condenser excitation transient stability device according to claim 7, characterized in that, The fault judgment module includes: A fault judgment unit, configured to judge whether a fault occurs in the system according to the change rate of the active power and the change amount of the original machine terminal voltage.

9. The distributed synchronous condenser excitation transient stability device according to claim 8, characterized in that, The fault judgment unit includes: A fault judgment subunit, configured to judge that a fault occurs in the system when the change rate is greater than a first preset threshold and the change amount is greater than a second preset threshold.

10. The distributed synchronous condenser excitation transient stability device according to claim 7, characterized in that, The control quantity determination module further includes: A second control quantity determination unit, configured to determine the control quantity as a second change amount when a third condition or a fourth condition is satisfied; Wherein, the second change amount is less than 0, the third condition is that the per-unit value of the active power is less than 0 and the per-unit value of the rotational speed is not less than 1; the fourth condition is that the per-unit value of the active power is not less than 0 and the per-unit value of the rotational speed is less than 1.

11. The distributed synchronous condenser excitation transient stability device according to claim 7, characterized in that, It further includes: A stop intervention condition determination module, configured to determine a stop modification condition according to the rotational speed and the rated rotational speed of the distributed synchronous condenser; A terminal voltage restoration module, configured to modify the current terminal voltage of the distributed synchronous condenser to the original machine terminal voltage when the stop modification condition is satisfied.

12. The distributed synchronous condenser excitation transient stability device according to claim 11, wherein The stop modification condition includes: The number of times the rotational speed exceeds the rated rotational speed is not less than a predetermined number of times.

13. A computer program product, comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by a processor, the steps of the distributed synchronous condenser excitation transient stability method according to any one of claims 1 to 6 are implemented.

14. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the steps of the distributed synchronous condenser excitation transient stability method according to any one of claims 1 to 6 are implemented.

15. A computer-readable storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by a processor, the steps of the distributed synchronous condenser excitation transient stability method according to any one of claims 1 to 6 are implemented.

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