An additional damping control method, device and system for suppressing active low-frequency oscillation

Abstract

The application discloses an additional damping control method, device and system for inhibiting active low-frequency oscillation, wherein a phase modifier power (or rotating speed) signal and a bus voltage frequency signal are introduced respectively, a signal change amount is subjected to low-pass filtering, gain amplification and multi-stage lead-lag correction, and then a damping control output signal is obtained, the signal is superimposed on a given and feedback deviation input point of a voltage closed-loop control of a phase modifier excitation system, and additional damping effect is generated by the phase modifier excitation system. The application provides an additional damping control for phase modifier excitation, the additional control can exert the influence capacity of the phase modifier on the dynamic stability of active power low-frequency oscillation, so that the existing and gradually put-into-operation phase modifiers with different capacities in the system can be used to participate in inhibiting system low-frequency oscillation.

Description

Technical Field

[0001] This invention relates to an additional damping control method and apparatus for suppressing low-frequency oscillations of active power in dynamic stability control of power systems, and particularly to an additional damping control method, apparatus and system for suppressing low-frequency oscillations of active power, belonging to the field of electrical engineering technology. Background Technology

[0002] In recent years, my country's wind power, photovoltaic, and other new energy sources have experienced explosive growth, with the proportion of new energy installed capacity in the power grid increasing daily. Large-scale new energy bases and long-distance, high-capacity AC / DC transmission are developing rapidly, all of which have provided opportunities for the application of new types of synchronous condensers. Large-scale new energy sources are often located at the end of interconnected power grids, where the grid structure is weak, local loads are small, and there is a lack of conventional supporting power sources nearby. Furthermore, the dynamic elastic support capacity of power electronic reactive power compensation equipment is less than half that of synchronous condensers of the same capacity. This results in prominent inertia frequency, power angle, and voltage issues, restricting power transmission capacity and the ability to absorb new energy. To address the voltage stability problems caused by the hollowing out of conventional units at DC sending-end new energy transmission and receiving-end load centers, the State Grid Corporation of China has installed large-capacity and distributed synchronous condensers at multiple DC sending / receiving-end converter stations and new energy power plants. This improves the short-circuit capacity and voltage stability of the sending / receiving-end power grids and enhances the short-circuit capacity and inertia support level of new energy power plants. Distributed synchronous condensers are expected to become standard equipment for new energy power plants in the future. As new energy power plants are built on a large scale, the number of synchronous condensers will gradually increase, so that new energy power plants can meet the grid connection requirements stipulated in GB38755 Power System Safety and Stability Guidelines.

[0003] Furthermore, renewable energy power plants are typically located at the end of the power grid in high-proportion renewable energy transmission systems, far from the grid center and with weak electrical connections to the system. The dynamic stability problem of low-frequency active power oscillations in high-proportion renewable energy transmission systems via AC / DC still exists. Simultaneously, low-frequency active power oscillations frequently occur between generator groups and regional power grids, as well as between regional power grids, during the dynamic process after system disturbances. Therefore, utilizing large, medium, and small synchronous condensers configured in the system to suppress low-frequency active power oscillations, and studying relevant additional controls without affecting the synchronous condensers' voltage and reactive power support capabilities to leverage their influence on low-frequency oscillation dynamic stability, can more fully utilize the stabilizing role of synchronous condensers in the grid and the benefits of their investment. This will improve the power security and stability level in weak grid areas, especially in areas where renewable energy is connected to the grid, and ensure high-quality power transmission capabilities.

[0004] Currently, publicly available technical documents only contain methods and systems for suppressing subsynchronous oscillations of new energy generating units based on synchronous condensers. These methods mainly target the oscillation suppression of subsynchronous frequency components, but no relevant information is found on suppression techniques for active low-frequency oscillations in the range of 0.1 to 3.0 Hz. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an additional damping control method, device and system for suppressing active low-frequency oscillations. This additional control can give full play to the influence of synchronous condensers on the dynamic stability of low-frequency oscillations, so as to utilize existing and future synchronous condensers of different capacities in the system to participate in suppressing low-frequency oscillations.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] An additional damping control method for suppressing low-frequency active power oscillations includes:

[0008] The rotation speed of the camera or the negative value of the active power of the camera is taken as the first input signal. The first input signal passes through the first measurement stage and the first DC blocking stage to obtain the first change. The first change passes through the first low-pass filter stage, and then through the first third-order lead-lag correction stage and the first upper and lower limit stage to obtain the first output signal.

[0009] The voltage frequency of the bus at the grid connection point of the generator unit at the camera access point is taken as the second input signal. The second input signal passes through the second measurement stage and the second DC blocking stage to obtain the second change. The second change passes through the second low-pass filter stage, and then through the second third-order lead-lag correction stage and the second upper and lower limit stage to obtain the second output signal.

[0010] After the first and second output signals are superimposed, they are used as the output of the additional damping controller of the synchronous condenser through the third upper and lower limit circuit. This output provides positive damping for the active power oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active power oscillation of the line between the new energy power generation unit and the system.

[0011] As a preferred embodiment of the method of the present invention, the specific steps for obtaining the first output signal are as follows:

[0012] Step 1: Obtain the first input signal U1, which passes through the first measurement stage and the first DC blocking stage to obtain the change ΔU1 of the first input signal. Then, it passes through the first low-pass filter stage and the gain coefficient K. s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 ;

[0013] Step 2, the change vector signal ΔU of the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 .

[0014] As a preferred embodiment of the method of the present invention, the first input signal U1 is taken as the rotor speed ω of the camera or the negative value of the active power of the camera -Pe.

[0015] As a preferred embodiment of the method of the present invention, in step 1, the calculation of the change ΔU1 of the first input signal when the first DC blocking element is of the second order is as shown in equation (a), and the calculation of the change ΔU1 of the first input signal when the first DC blocking element is of the first order is as shown in equation (b):

[0016]

[0017]

[0018] Where T5 is the time constant of the first measurement stage; T w1 T is the time constant of the first-order DC blocking element. w2 The time constant of the second-order DC blocking element; s represents the differential operator;

[0019] The change vector signal ΔU of the first input signal in1 The calculation is shown in equation (c):

[0020]

[0021] Among them, K s1 For the changing vector signal ΔU in1 The gain coefficient; a n2 a n1 a n0 a m1 and a m0 These are the coefficients of the first low-pass filter stage.

[0022] As a preferred embodiment of the method of the present invention, in step 2, the signal ΔU is calculated according to equation (d). * out1 , signal ΔU * out1 The first output signal ΔU is obtained after the first upper and lower limiting circuit. out1 :

[0023]

[0024] Among them, T 11 ~T 16 The time constant of the first and third order lead-lag compensation element; the first upper and lower limit values ​​are K. L1 Take 5% to 10% of the per-unit value.

[0025] As a preferred embodiment of the method of the present invention, the specific steps for obtaining the second output signal are as follows:

[0026] Step 3: Obtain the second input signal U2, which passes through the second measurement stage and the second DC blocking stage to obtain the change ΔU2 of the second input signal. Then, it passes through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 ;

[0027] Step 4, the change vector signal ΔU of the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 .

[0028] As a preferred embodiment of the method of the present invention, the second input signal U2 is obtained from the bus voltage frequency f at the grid connection point of the power generation unit at the camera access point. s .

[0029] As a preferred embodiment of the method of the present invention, in step 3, the calculation of the change ΔU2 of the second input signal when the second DC blocking element is of the second order is as shown in equation (e), and the calculation of the change ΔU2 of the second input signal when the second DC blocking element is of the first order is as shown in equation (f):

[0030]

[0031]

[0032] Where T6 is the time constant of the measurement process; T w3 T is the time constant of the first-order DC blocking element. w4 The time constant of the second-order DC blocking element; s represents the differential operator;

[0033] The change vector signal ΔU of the second input signal in2 The calculation is shown in equation (g):

[0034]

[0035] Among them, K s2 For the changing vector signal ΔU in2 The gain coefficient; a k2 a k1 a k0 a j1 and a j0 These are the coefficients of the second low-pass filter stage.

[0036] As a preferred embodiment of the method of the present invention, in step 4, the signal ΔU is calculated according to formula (h). * out2 , signal ΔU * out2The second output signal ΔU is obtained after the second upper and lower limiting circuit. out2 :

[0037]

[0038] Among them, T 21 ~T 26 The time constant of the second and third order lead-lag compensation stage; the second upper and lower limit values ​​are K. L2 Take 5% to 10% of the per-unit value.

[0039] As a preferred embodiment of the method of the present invention, the specific steps for generating the positive damping effect are as follows:

[0040] Step 5, for the first output signal ΔU out1 Second output signal ΔU out2 The signals are superimposed to obtain the output signal ΔU. out ;

[0041] Step 6, output signal ΔU out After passing through the third upper and lower limiting stage, the output signal ΔU becomes the additional damping controller of the camera modulator. pss ;

[0042] Step 7, convert the output signal ΔU of the additional damping controller of the camera to... pss The given signal U superimposed on the voltage closed-loop control of the synchronous condenser excitation system ref With feedback signal U g The deviation input point generates additional positive damping through the synchronous condenser excitation system.

[0043] An additional damping control device for suppressing active low-frequency oscillations, the device comprising a first input signal acquisition module, a first input signal processing module, a second input signal acquisition module, a second input signal processing module, and a superposition module, wherein:

[0044] The first input signal acquisition module is used to acquire the first input signal U1;

[0045] The first input signal processing module is used to obtain the change ΔU1 of the first input signal U1 by passing it through the first measurement stage and the first DC blocking stage in sequence, and then through the first low-pass filter stage and the gain coefficient K. s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 The vector signal ΔU representing the change in the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 ;

[0046] The second input signal acquisition module is used to acquire the second input signal U2;

[0047] The second input signal processing module is used to obtain the change ΔU2 of the second input signal U2 by passing it through the second measurement stage and the second DC blocking stage in sequence, and then passing it through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 The vector signal ΔU representing the change in the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 ;

[0048] The superposition module is used to superimpose the first output signal ΔU out1 Second output signal ΔU out2 After being superimposed and passed through the third upper and lower limiting stage, the signal ΔU is used as the output signal of the additional damping controller of the camera modulator. pss It has a positive damping effect on the active power oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active power oscillation of the line between the new energy power generation unit and the system.

[0049] The control system based on the aforementioned additional damping control device for suppressing low-frequency active power oscillations includes a superposition element and a control element for the synchronous condenser excitation system, wherein:

[0050] The superposition step is used to combine the output signal ΔU of the synchronous condenser's additional damping controller. pss The given signal U superimposed on the voltage closed-loop control of the synchronous condenser excitation system ref With feedback signal U g The deviation input point;

[0051] The control loop of the synchronous condenser excitation system is used to generate additional positive damping effect on the active oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active oscillation of the line between the new energy power generation unit and the system, based on the signal generated by the deviation input point.

[0052] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the additional damping control method for suppressing active low-frequency oscillations as described above.

[0053] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the additional damping control method for suppressing active low-frequency oscillations as described above.

[0054] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0055] 1. This invention introduces the synchronous condenser power (or speed) signal and the bus voltage frequency signal respectively. The signal changes are filtered by low-pass, amplified by gain and multi-stage lead-lag correction to obtain the damping control output signal. This signal is superimposed on the deviation input point between the given and feedback of the synchronous condenser excitation system voltage closed-loop control, thereby generating an additional damping effect through the synchronous condenser excitation system.

[0056] 2. This invention provides positive damping for low-frequency active power oscillations and low-frequency line oscillations between new energy power generation units and the system during the dynamic process after system disturbance, through synchronous condenser excitation control, thereby enhancing the dynamic stability of the system; it also gives full play to the stabilizing role of synchronous condensers in the power grid and maximizes the benefits of investing in synchronous condensers, thereby improving the power safety and stability level in weak areas of the power grid, especially in areas where new energy is connected to the power grid. Attached Figure Description

[0057] Figure 1 This is a block diagram of the additional damping control of the synchronous condenser of the present invention;

[0058] Figure 2 This is a schematic diagram of the main wiring for connecting a synchronous condenser to the power grid system;

[0059] Figure 3 This is a simulation of the line transmission power oscillation after system disturbance when the additional damping control of the synchronous condenser is not applied. In this simulation, (a) is the active power of the line and (b) is the reactive power output of the synchronous condenser.

[0060] Figure 4 This is a simulation of the line transmission power oscillation after the system is disturbed following the implementation of additional damping control of the synchronous condenser. In this simulation, (a) represents the active power of the line, and (b) represents the reactive power output of the synchronous condenser. Detailed Implementation

[0061] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0062] With the increasing number of large, medium and small synchronous condensers configured in the power grid system, utilizing the ability of synchronous condensers to participate in suppressing low-frequency oscillations of active power in the system and to exert their influence on the dynamic stability of low-frequency oscillations can more fully leverage the stabilizing role of synchronous condensers in the power grid and the benefits brought by the investment in synchronous condensers, thereby improving the power security and stability level in weak areas of the power grid.

[0063] like Figure 1 The diagram shown is a block diagram of the additional damping control model for the synchronous condenser of the present invention. The design and implementation steps are as follows:

[0064] 1) Measure the rotor speed ω of the synchronous condenser or the active power Pe of the synchronous condenser. The active power Pe signal of the synchronous condenser needs to be inverted. The two are switched by a selector switch and used as the first input signal U1.

[0065] The first input signal U1 passes through the first measurement stage and the first DC blocking stage to obtain the change ΔU1 of the first input signal. Then it passes through the first low-pass filter stage and the gain coefficient K. s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 .

[0066] The change in the first input signal ΔU1 when the first DC blocking element is a second-order DC blocking element is calculated as shown in equation (a), and the change in the first input signal ΔU1 when the first DC blocking element is a first-order DC blocking element is calculated as shown in equation (b).

[0067]

[0068]

[0069] Where T5 is the time constant of the measurement process, which is set according to the actual inertial delay time of the first signal measurement; T w1 T is the time constant of the first DC blocking element. w2 is the time constant of the second DC blocking element; s represents the differential operator.

[0070] The measurement time constant represents the time it takes for the effective measured value of a certain analog quantity to reach 63.2% of the final measured value. It indicates how quickly a measurement result is obtained for that analog quantity. The measurement time constant varies for different analog quantities. For example, if the measurement system's time constant for measuring a certain analog quantity is 15ms, then 15ms is the time from the sudden change in the analog quantity until its measured value reaches 63.2% of the actual final value. The measurement time constant should be set according to the actual measurement time constant of the measurement system for that analog quantity.

[0071] The change vector signal ΔU of the first input signal in1 The calculation is shown in equation (c):

[0072]

[0073] Among them, K s1 For the changing vector signal ΔU in1 The gain coefficient; a n2 a n1 a n0 a m1 and a m0 These are the coefficients of the first low-pass filter stage.

[0074] 2) The vector signal ΔU representing the change in the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 .

[0075] The signal ΔU is calculated according to formula (d). * out1 , signal ΔU * out1 The first output signal ΔU is obtained after the first upper and lower limiting circuit. out1 :

[0076]

[0077] Among them, T 11 ~T 16 The time constant of the first and third order lead-lag compensation element; the first upper and lower limit values ​​are K. L1 Generally, it is taken as 5% to 10% of the per-unit value.

[0078] 3) Figure 2 The diagram shows the main wiring diagram of a synchronous condenser connected to the power grid. The synchronous condenser connection point has an electrical connection to the nearby generating units via the same busbar. The frequency f of the busbar voltage at the grid connection point of the generating units near the synchronous condenser connection point is measured. s , which serves as the second input signal U2.

[0079] The second input signal U2, after passing through the second measurement stage and the second DC blocking stage, yields the change ΔU2 of the second input signal. This change is then passed through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 .

[0080] When the second DC blocking element is a second-order DC blocking element, the change in the second input signal ΔU2 is calculated as shown in equation (e). When the second DC blocking element is a first-order DC blocking element, the change in the second input signal ΔU2 is calculated as shown in equation (f).

[0081]

[0082]

[0083] Where T6 is the time constant of the measurement process, which is set according to the actual inertial delay time of the second signal measurement; T w3 T is the time constant of the first DC blocking element. w4 is the time constant of the second DC blocking element; s represents the differential operator.

[0084] The change vector signal ΔU of the second input signalin2 The calculation is shown in the following formula (g):

[0085]

[0086] Among them, K s2 For the changing vector signal ΔU in2 The gain coefficient; a k2 a k1 a k0 a j1 and a j0 These are the coefficients of the second low-pass filter stage.

[0087] 4) The vector signal ΔU representing the change in the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 .

[0088] The signal ΔU is calculated according to formula (h). * out2 , signal ΔU * out2 The second output signal ΔU is obtained after the second upper and lower limiting circuit. out2 :

[0089]

[0090] Among them, T 21 ~T 26 The time constant of the second and third order lead-lag compensation stage; the second upper and lower limit values ​​are K. L2 Generally, it is taken as 5% to 10% of the per-unit value.

[0091] 5) The first output signal ΔU obtained from step 2) out1 The second output signal ΔU obtained in step 4) out2 The signals are superimposed to obtain the output signal ΔU. out The calculation is shown in equation (i):

[0092] ΔU out =ΔU out1 +ΔU out2 (i)

[0093] 6) The output signal ΔU obtained in step 5) out After passing through the third upper and lower limiting stage, the output ΔU is used as the additional damping controller of the camera modulator. pss The third upper and lower limit values ​​are K. L Generally, 10% is taken as the per-unit value.

[0094] 7) The additional damping controller output ΔU obtained from step 6) pssThe signal is superimposed on the input point of the given and feedback deviation of the voltage closed-loop control of the synchronous condenser excitation system, and generates an additional damping effect through the synchronous condenser excitation system.

[0095] Figure 3 (a) and (b) show the simulation of power oscillation transmitted on the transmission line between the new energy power generation unit and the system after the system is disturbed when the additional damping control of the synchronous condenser is not applied. The active oscillation damping ratio is 0.07, the number of oscillations is relatively large, and the oscillation subsides after a long time.

[0096] Figure 4 Figures (a) and (b) show the simulation of power oscillation transmitted on the transmission line between the new energy power generation unit and the system after the system is disturbed after the additional damping control of the synchronous condenser is put into operation. At this time, the active oscillation damping ratio is increased to 0.198, the number of oscillations is significantly reduced, and the oscillation subsides after a short time.

[0097] In the method for implementing additional damping control of the synchronous condenser of the present invention: the first input signal U1 is taken from the rotational speed ω of the synchronous condenser or the negative value of the active power of the synchronous condenser -Pe. After passing through a DC blocking circuit to obtain the change, and passing through a low-pass filter circuit to reduce measurement noise, it is then compensated for the lag characteristics of the excitation system of the synchronous condenser by a third-order lead-lag circuit, so that the torque generated by its additional control is near the Δω axis of the synchronous condenser. Therefore, it can provide effective positive damping for the active power oscillation of the synchronous condenser and the system after the system is disturbed; the second input signal U2 is taken from the bus voltage frequency f of the generator unit near the grid connection point of the synchronous condenser. s The change is obtained through a DC blocking stage and then reduced by a low-pass filter to reduce measurement noise and suppress non-low-frequency oscillation mode signals. After the third-order lead-lag stage compensates for the lag characteristics of the synchronous condenser, the torque generated by the additional control is in a certain phase relationship with the change in the line transmission power. Therefore, it provides an effective positive damping effect on the active low-frequency oscillation of the line between the new energy power generation unit and the system. The first and second output signals each have their own adjustable gain coefficients and amplitude limits, which can change the magnitude and weight of their roles in the additional damping control. The synthesized additional damping control can produce a damping effect on the above-mentioned oscillation conditions.

[0098] This invention also proposes an additional damping control device for suppressing active low-frequency oscillations. The device includes a first input signal acquisition module, a first input signal processing module, a second input signal acquisition module, a second input signal processing module, and a superposition module, wherein:

[0099] The first input signal acquisition module is used to acquire the first input signal U1;

[0100] The first input signal processing module is used to process the first input signal U1 sequentially through the first measurement stage and the first DC blocking stage to obtain the change ΔU1 of the first input signal, and then through the first low-pass filter stage and the gain coefficient K.s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 The vector signal ΔU representing the change in the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 ;

[0101] The second input signal acquisition module is used to acquire the second input signal U2;

[0102] The second input signal processing module is used to process the second input signal U2 sequentially through the second measurement stage and the second DC blocking stage to obtain the change ΔU2 of the second input signal, and then through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 The vector signal ΔU representing the change in the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 ;

[0103] The superposition module is used to superimpose the first output signal ΔU out1 Second output signal ΔU out2 After being superimposed and passed through the third upper and lower limiting stage, the signal ΔU is used as the output signal of the additional damping controller of the camera modulator. pss It has a positive damping effect on the active power oscillations of the synchronous condenser and the system itself after the system is disturbed, as well as the low-frequency active power oscillations of the lines between the new energy power generation units and the system.

[0104] This invention also proposes an additional damping control system for suppressing low-frequency active power oscillations. The control system includes the aforementioned control device, a superposition element, and a control element for the synchronous condenser excitation system, wherein:

[0105] The superposition stage is used to combine the output signal ΔU of the synchronous condenser's additional damping controller. pss The given signal U superimposed on the voltage closed-loop control of the synchronous condenser excitation system ref With feedback signal U g The deviation input point;

[0106] The control loop of the synchronous condenser excitation system is used to generate additional positive damping effect on the active oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active oscillation of the line between the new energy power generation unit and the system, based on the signal generated by the deviation input point.

[0107] All relevant content of each step involved in the aforementioned embodiments of the additional damping control method for suppressing active low-frequency oscillations can be referenced to the functional description of the corresponding functional modules of the additional damping control device and system for suppressing active low-frequency oscillations in the embodiments of this application, and will not be repeated here.

[0108] Based on the same inventive concept, embodiments of this application provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps of the aforementioned additional damping control method for suppressing active low-frequency oscillations.

[0109] Based on the same inventive concept, embodiments of this application provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the aforementioned additional damping control method for suppressing active low-frequency oscillations.

[0110] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0111] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0112] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0114] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for additional damping control to suppress low-frequency active power oscillations, characterized in that, include: The camera's rotation speed or the negative value of its active power is taken as the first input signal. The first input signal passes through the first measurement stage and the first DC blocking stage to obtain the first change. The first change passes through the first low-pass filter stage, and then through the first third-order lead-lag correction stage and the first upper and lower limit stage to obtain the first output signal. The voltage frequency of the bus at the grid connection point of the generator unit at the camera access point is taken as the second input signal. The second input signal passes through the second measurement stage and the second DC blocking stage to obtain the second change. The second change passes through the second low-pass filter stage, and then through the second third-order lead-lag correction stage and the second upper and lower limit stage to obtain the second output signal. After the first and second output signals are superimposed, they are used as the output of the additional damping controller of the synchronous condenser through the third upper and lower limit circuit. This output provides positive damping for the active oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active oscillation of the line between the new energy power generation unit and the system. The specific steps for generating positive damping are as follows: Step 5, for the first output signal ΔU out1 Second output signal ΔU out2 The signals are superimposed to obtain the output signal ΔU. out ; Step 6, output signal ΔU out After passing through the third upper and lower limiting stage, the output signal ΔU becomes the additional damping controller of the camera modulator. pss ; Step 7, convert the output signal ΔU of the additional damping controller of the camera to... pss The given signal U superimposed on the voltage closed-loop control of the synchronous condenser excitation system ref With feedback signal U g The deviation input point generates additional positive damping through the synchronous condenser excitation system.

2. The additional damping control method for suppressing active low-frequency oscillations according to claim 1, characterized in that, The specific steps for obtaining the first output signal are as follows: Step 1: Obtain the first input signal U1, which passes through the first measurement stage and the first DC blocking stage to obtain the change ΔU1 of the first input signal. Then, it passes through the first low-pass filter stage and the gain coefficient K. s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 ; Step 2, the change vector signal ΔU of the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 .

3. The additional damping control method for suppressing active low-frequency oscillations according to claim 2, characterized in that, The first input signal U1 is taken as the rotor speed ω of the camera or the negative value of the active power of the camera -Pe.

4. The additional damping control method for suppressing active low-frequency oscillations according to claim 2, characterized in that, In step 1, the calculation of the change ΔU1 of the first input signal when the first DC blocking element is of the second order is shown in equation (a), and the calculation of the change ΔU1 of the first input signal when the first DC blocking element is of the first order is shown in equation (b). (a) (b) Where T5 is the time constant of the first measurement stage; T w1 T is the time constant of the first-order DC blocking element. w2 The time constant of the second-order DC blocking element; s represents the differential operator; The change vector signal ΔU of the first input signal in1 The calculation is shown in equation (c): (c) in, For the changing vector signal ΔU in1 Gain coefficient; and These are the coefficients of the first low-pass filter stage.

5. The additional damping control method for suppressing active low-frequency oscillations according to claim 4, characterized in that, In step 2, the signal is calculated according to equation (d). ,Signal The first output signal ΔU is obtained after the first upper and lower limiting circuit. out1 : (d) Among them, T 11 ~T 16 The time constant of the first and third order lead-lag compensation element; the first upper and lower limit values ​​are K. L1 Take 5% to 10% of the per-unit value.

6. The additional damping control method for suppressing active low-frequency oscillations according to claim 1, characterized in that, The specific steps for obtaining the second output signal are as follows: Step 3: Obtain the second input signal U2, which passes through the second measurement stage and the second DC blocking stage to obtain the change ΔU2 of the second input signal. Then, it passes through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 ; Step 4, the change vector signal ΔU of the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 .

7. The additional damping control method for suppressing active low-frequency oscillations according to claim 6, characterized in that, The second input signal U2 modulates the frequency f of the bus voltage at the grid connection point of the generator unit at the camera access point. s .

8. The additional damping control method for suppressing active low-frequency oscillations according to claim 6, characterized in that, In step 3, the calculation of the change ΔU2 of the second input signal when the second DC blocking element is of the second order is shown in equation (e), and the calculation of the change ΔU2 of the second input signal when the second DC blocking element is of the first order is shown in equation (f). (e) (f) Where T6 is the time constant of the measurement process; T w3 T is the time constant of the first-order DC blocking element. w4 The time constant of the second-order DC blocking element; s represents the differential operator; The change vector signal ΔU of the second input signal in2 The calculation is shown in equation (g): (g) in, For the changing vector signal ΔU in2 Gain coefficient; and These are the coefficients of the second low-pass filter stage.

9. The additional damping control method for suppressing active low-frequency oscillations according to claim 8, characterized in that, In step 4, the signal is calculated according to formula (h). ,Signal The second output signal ΔU is obtained after the second upper and lower limiting circuit. out2 : (h) Among them, T 21 ~T 26 The time constant of the second and third order lead-lag compensation stage; the second upper and lower limit values ​​are K. L2 Take 5% to 10% of the per-unit value.

10. A control system based on an additional damping control device for suppressing low-frequency active power oscillations, characterized in that, The device includes a first input signal acquisition module, a first input signal processing module, a second input signal acquisition module, a second input signal processing module, and a superposition module, wherein: The first input signal acquisition module is used to acquire the first input signal U1; The first input signal processing module is used to obtain the change ΔU1 of the first input signal U1 by passing it through the first measurement stage and the first DC blocking stage in sequence, and then through the first low-pass filter stage and the gain coefficient K. s1 After amplification, the change vector signal ΔU of the first input signal is obtained. in1 The vector signal ΔU representing the change in the first input signal in1 The first output signal ΔU is obtained after passing through the first and third order lead-lag correction circuit and the first upper and lower limit circuit. out1 ; The second input signal acquisition module is used to acquire the second input signal U2; The second input signal processing module is used to obtain the change ΔU2 of the second input signal U2 by passing it through the second measurement stage and the second DC blocking stage in sequence, and then passing it through the second low-pass filter stage and the gain coefficient K. s2 After amplification, the change vector signal ΔU of the second input signal is obtained. in2 The vector signal ΔU representing the change in the second input signal in2 The second output signal ΔU is obtained after passing through the second and third order lead-lag correction circuits and the second upper and lower limit circuits. out2 ; The superposition module is used to superimpose the first output signal ΔU out1 Second output signal ΔU out2 After being superimposed and passed through the third upper and lower limiting stage, the signal ΔU is used as the output signal of the additional damping controller of the camera modulator. pss It has a positive damping effect on the active power oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active power oscillation of the line between the new energy power generation unit and the system. The control system includes a superposition element and a control element for the synchronous condenser excitation system, wherein: The superposition step is used to combine the output signal ΔU of the synchronous condenser's additional damping controller. pss The given signal U superimposed on the voltage closed-loop control of the synchronous condenser excitation system ref With feedback signal U g The deviation input point; The control loop of the synchronous condenser excitation system is used to generate additional positive damping effect on the active oscillation of the synchronous condenser and the system after the system is disturbed, as well as the low-frequency active oscillation of the line between the new energy power generation unit and the system, based on the signal generated by the deviation input point.

11. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the additional damping control method for suppressing active low-frequency oscillations as described in any one of claims 1 to 9.

12. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the additional damping control method for suppressing active low-frequency oscillations as described in any one of claims 1 to 9.

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