Method for improving robustness of mining variable-frequency power supply system based on two-stage networked compensation

Abstract

The invention provides a mining variable-frequency power supply system robustness improvement method based on two-stage networked compensation. The method comprises the following steps: constructing a robust control system according to a mining variable-frequency power supply system; judging whether the mining variable-frequency power supply system is stable or not through a robust control system; if it is judged that the mining variable-frequency power supply system is unstable, secondary compensation is carried out on the mining variable-frequency power supply system; and the sampling period of the robust control system is optimized. The technical problem that in the prior art, when facing external disturbance, a mining variable-frequency power supply system is prone to deviating from the balance state and cannot recover to the original balance state in time, power supply is not stable, and therefore the safety and efficiency of mine production are affected is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system control, and in particular to a method for improving the robustness of a mining variable frequency power supply system based on two-stage networked compensation. Background Art

[0002] The development of variable-frequency power supply systems for mines faces challenges stemming from the randomness and volatility of distributed resources, specifically the significant impact of high-proportion, highly uncertain distributed renewable energy sources. Intermittency and volatility exist on both the supply and demand sides, and these uncertainties pose new challenges to the operational optimization of variable-frequency power supply systems for mines. Networked control technology is a novel power system control approach that effectively controls diverse power equipment within the complex environment of variable-frequency power supply systems, manages underlying micro-sources, and manages the load of the mine variable-frequency power supply system. Problems with a micro-source can be promptly monitored and shut down, facilitating capacity expansion.

[0003] However, there is at least one of the following problems in the related technology: when facing external disturbances, the variable frequency power supply system for mining in the existing technology is prone to deviate from the equilibrium state and cannot be restored to the original equilibrium state in time, resulting in unstable power supply, thereby affecting the safety and efficiency of mine production. Summary of the Invention

[0004] The technical problem solved by the present invention is that the variable frequency power supply system for mining in the existing technology is prone to deviate from the equilibrium state when facing external disturbances and cannot be restored to the original equilibrium state in time, resulting in unstable power supply, thereby affecting the safety and efficiency of mine production.

[0005] To solve the above problems, the present invention provides a method for improving the robustness of a mine-used variable frequency power supply system based on two-stage networked compensation, comprising: constructing a robust control system according to the mine-used variable frequency power supply system; judging whether the mine-used variable frequency power supply system is stable through the robust control system; if the mine-used variable frequency power supply system is determined to be unstable, performing secondary compensation on the mine-used variable frequency power supply system; and optimizing the sampling period of the robust control system.

[0006] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: by building a robust control system to judge the system stability, and performing secondary compensation on the mine-used variable frequency power supply system when the mine-used variable frequency power supply system is unstable, and then optimizing the sampling period of the robust control system, the robustness of the mine-used variable frequency power supply system is improved in multiple aspects, so that it can better cope with various interference and uncertainty factors in a complex mining environment, ensure the stable operation of the system, and improve production efficiency and safety.

[0007] In one embodiment of the present invention, a robust control system is constructed based on a mine-used variable frequency power supply system, including: constructing an input formula for the mine-used variable frequency power supply system based on a communication delay; calculating a specific value of the communication delay and substituting it into the input formula; and designing a remote robust controller based on the mine-used variable frequency power supply system.

[0008] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: considering the communication delay factor, constructing the input formula and calculating the specific value of the communication delay and bringing it into the input formula, designing a remote robust controller based on the mine variable frequency power supply system, which can more accurately model and control the mine variable frequency power supply system, improve the reliability and accuracy of the robust control system, further enhance the judgment and control capabilities of the system stability, and better adapt to networked compensation scenarios.

[0009] In one embodiment of the present invention, the input formula satisfies the following formula 1; wherein formula 1 is: ; Among them, u(t) is the input, t is the time parameter, t m is the time of the mth sampling, is the communication delay, T s is the sampling period; the calculation of communication delay satisfies the following formula 2; where formula 2 is: ; Where m is the summation upper limit, k is the weight index, T send is the data transmission time interval; the design of the remote robust controller satisfies the following formula 3; where formula 3 is: ; Where K is the feedback gain matrix.

[0010] In one embodiment of the present invention, whether a mine-used variable frequency power supply system is stable is determined by a robust control system, including: determining a closed-loop system model under state response control of the robust control system; setting a sampling period and a sampling optimization calculation range of the robust control system; determining the asymptotic stability condition of the mine-used variable frequency power supply system according to the Schur complement lemma, and determining whether the mine-used variable frequency power supply system is stable.

[0011] Compared with the existing technology, the technical effects achieved by adopting this technical solution are: determining the closed-loop system model, setting the sampling period and sampling optimization calculation range, and using the Schur complement lemma to determine the asymptotic stability condition to judge the system stability, providing a systematic and scientific stability judgment method, which can timely and accurately detect the instability of the system and provide a reliable basis for subsequent sampling period optimization and other measures.

[0012] In one embodiment of the present invention, the closed-loop system model satisfies the following formula 4; wherein, formula 4 is: ; x(k) is the state vector of the mine variable frequency power supply system at time k, A d is the state transfer matrix of the mine variable frequency power supply system, B10 is the first input matrix, B 11 is the second input matrix, B2 is the third input matrix, z(k) is the output vector of the mine variable frequency power supply system at time k, C is the output matrix, D1K is the matrix related to the input, D2 is the matrix related to the interference, and w(k) is the vector group related to the interference.

[0013] In one embodiment of the present invention, the calculation of the asymptotic stability condition satisfies the following formula 5; wherein formula 5 is: ; Wherein, Q is the first asymptotically stable matrix representing positive definiteness, and P is the second asymptotically stable matrix representing positive definiteness.

[0014] In one embodiment of the present invention, secondary compensation is performed on a variable frequency power supply system for mining, including: determining basic information of the grid bus through an iterative Fourier transform detection method; calculating fundamental frequency information of the grid voltage; uploading the basic information and fundamental frequency information to a robust control system, and comparing them with a local droop control output to obtain a secondary compensation value; and compensating the secondary compensation value to the local droop control output terminal through the robust control system.

[0015] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the basic information of the grid bus is obtained and the fundamental frequency information of the grid voltage is calculated through the iterative Fourier transform detection method. By uploading the basic information and fundamental frequency information to the robust control system, the secondary compensation value is obtained by comparing with the local droop control output for compensation. It can compensate for the influencing factors such as grid fluctuations in a timely and accurate manner, further improving the stability and robustness of the mine-used variable frequency power supply system under complex working conditions such as grid fluctuations, and ensuring the output reliability and quality of the system.

[0016] In one embodiment of the present invention, the calculation of the fundamental frequency information satisfies the following formula 6; wherein formula 6 is: ;in, ; ; , N is a natural number.

[0017] In one embodiment of the present invention, the sampling period of the robust control system is optimized, including: determining the robust stability conditions of the mine variable frequency power supply system through Lyapunov stability theory; calculating the system robustness that meets the robust stability conditions; judging whether the sampling period can complete the numerical calculation within the sampling optimization calculation range according to the system robustness; if the sampling period can complete the numerical calculation within the sampling optimization calculation range, then entering the sampling period into the sampling period set; resetting the sampling period; screening out data with a shorter sampling period in the sampling period set and recording it as the optimal sampling period.

[0018] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: the robust stability conditions are determined based on Lyapunov stability theory, the system robustness is calculated and the optimal sampling period is screened out, and the sampling period can be optimized systematically and targetedly, so that the robust control system can be better configured in the key parameter of the sampling period, thereby significantly improving the robustness of the mine-used variable frequency power supply system, enhancing its ability to cope with uncertain factors and interference, and ensuring the stable operation of the system.

[0019] In one embodiment of the present invention, the robust stability condition is determined to satisfy the following formula 7; wherein formula 7 is: ;in, is the performance index matrix, G is the transfer function matrix, Y is the system output matrix, and I is the identity matrix.

[0020] After adopting the technical solution of the present invention, the following technical effects can be achieved: (1) By building a robust control system to judge the system stability and performing secondary compensation on the mine variable frequency power supply system when it is unstable, the sampling period of the robust control system is optimized, thus improving the robustness of the mine variable frequency power supply system in many aspects, enabling it to better cope with various interference and uncertainty factors in a complex mining environment, ensuring the stable operation of the system, and improving production efficiency and safety; (2) Considering the communication delay factor, the input formula is constructed and the specific value of the communication delay is calculated and substituted into the input formula. A remote robust controller is designed based on the mine variable frequency power supply system. This can more accurately model and control the mine variable frequency power supply system, improve the reliability and accuracy of the robust control system, further enhance the ability to judge and control the system stability, and better adapt to the network compensation scenario; (3) Determine the closed-loop system model, set the sampling period and sampling optimization calculation range, and use Schur's complement lemma to determine the asymptotic stability condition to judge the system stability. This provides a systematic and scientific stability judgment method that can detect the instability of the system in a timely and accurate manner, providing a reliable basis for subsequent sampling period optimization and other measures; (4) The basic information of the grid bus is obtained through the iterative Fourier transform detection method and the fundamental frequency information of the grid voltage is calculated. By uploading the basic information and fundamental frequency information to the robust control system, the secondary compensation value is obtained by comparing it with the local droop control output for compensation. It can compensate for the influencing factors such as grid fluctuations in a timely and accurate manner, further improving the stability and robustness of the mine variable frequency power supply system under complex working conditions such as grid fluctuations, and ensuring the output reliability and quality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings to be used in describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts. Figure 1 A flow chart of a method for improving the robustness of a mining variable frequency power supply system based on two-stage networked compensation is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connection, connection, or integral connection; they can refer to mechanical connection or electrical connection; they can refer to direct connection or indirect connection through an intermediate medium; and they can refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0024] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] See also Figure 1 , which is a flow chart of a method for improving the robustness of a mine-used variable frequency power supply system based on two-stage networked compensation provided by an embodiment of the present invention. Specifically, a method for improving the robustness of a mine-used variable frequency power supply system based on two-stage networked compensation includes: S10: Construct a robust control system based on the mine variable frequency power supply system; S20: Determine whether the mine variable frequency power supply system is stable through the robust control system; S30: If it is determined that the mine variable frequency power supply system is unstable, the sampling period of the robust control system is optimized; S40: Perform secondary compensation on the mine variable frequency power supply system.

[0026] Furthermore, by building a robust control system to judge the system stability and performing secondary compensation on the mine-used variable frequency power supply system when it is unstable, and then optimizing the sampling period of the robust control system, the robustness of the mine-used variable frequency power supply system is improved in many aspects, enabling it to better cope with various interference and uncertainty factors in complex mining environments, ensuring the stable operation of the system, and improving production efficiency and safety.

[0027] Preferably, a robust control system is constructed based on a mine-used variable frequency power supply system, including: constructing an input formula for the mine-used variable frequency power supply system based on the communication delay; calculating a specific value of the communication delay and substituting it into the input formula; and designing a remote robust controller based on the mine-used variable frequency power supply system.

[0028] Furthermore, considering the communication delay factor, an input formula is constructed and the specific value of the communication delay is calculated and substituted into the input formula. A remote robust controller is designed based on the mine-used variable frequency power supply system, which can more accurately model and control the mine-used variable frequency power supply system, improve the reliability and accuracy of the robust control system, further enhance the ability to judge and control the system stability, and better adapt to networked compensation scenarios.

[0029] Preferably, the input formula satisfies the following formula 1; wherein, formula 1 is: ; Among them, u(t) is the input, t is the time parameter, t m is the time of the mth sampling, is the communication delay, T s is the sampling period; the calculation of communication delay satisfies the following formula 2; where formula 2 is: ; Where m is the summation upper limit, k is the weight index, T send is the data transmission time interval; the design of the remote robust controller satisfies the following formula 3; where formula 3 is: ; Where K is the feedback gain matrix.

[0030] Preferably, the stability of the mine-used variable frequency power supply system is determined by a robust control system, including: determining a closed-loop system model under the state response control of the robust control system; setting the sampling period and sampling optimization calculation range of the robust control system; determining the asymptotic stability condition of the mine-used variable frequency power supply system according to the Schur complement lemma, and determining whether the mine-used variable frequency power supply system is stable.

[0031] Furthermore, the closed-loop system model is determined, the sampling period and the sampling optimization calculation range are set, and the Schur complement lemma is used to determine the asymptotic stability conditions to judge the system stability. This provides a systematic and scientific stability judgment method that can detect system instability in a timely and accurate manner, providing a reliable basis for subsequent sampling period optimization and other measures.

[0032] Preferably, the closed-loop system model satisfies the following formula 4; wherein, formula 4 is: ; x(k) is the state vector of the mine variable frequency power supply system at time k, A d is the state transfer matrix of the mine variable frequency power supply system, B 10 is the first input matrix, B 11 is the second input matrix, B2 is the third input matrix, z(k) is the output vector of the mine variable frequency power supply system at time k, C is the output matrix, D1K is the matrix related to the input, D2 is the matrix related to the interference, and w(k) is the vector group related to the interference.

[0033] Preferably, the calculation of the asymptotic stability condition satisfies the following formula 5; wherein formula 5 is: ; Wherein, Q is the first asymptotically stable matrix representing positive definiteness, and P is the second asymptotically stable matrix representing positive definiteness.

[0034] Preferably, secondary compensation is performed on the mine-used variable frequency power supply system, including: determining the basic information of the grid bus through an iterative Fourier transform detection method; calculating the fundamental frequency information of the grid voltage; uploading the basic information and the fundamental frequency information to the robust control system, and comparing them with the local droop control output to obtain a secondary compensation value; and compensating the secondary compensation value to the local droop control output end through the robust control system.

[0035] Furthermore, the basic information of the grid bus is obtained and the fundamental frequency information of the grid voltage is calculated through the iterative Fourier transform detection method. By uploading the basic information and fundamental frequency information to the robust control system and comparing them with the local droop control output, a secondary compensation value is obtained for compensation. This can timely and accurately compensate for factors such as grid fluctuations, further improving the stability and robustness of the mine-used variable frequency power supply system under complex working conditions such as grid fluctuations, and ensuring the output reliability and quality of the system.

[0036] Preferably, the calculation of the fundamental frequency information satisfies the following formula 6; wherein, formula 6 is: ;in, ; ; , N is a natural number.

[0037] Furthermore, when the grid frequency fluctuates, the fluctuation of the grid frequency is recorded as , , when synchronously sampled, .

[0038] Furthermore, if the three-phase power grid is balanced and has no distortion, then The grid voltage vector discreteness of the axis is satisfied by the following formula 8; where formula 8 is: ;in, is the fundamental amplitude of the grid voltage; is the initial phase angle.

[0039] Furthermore, when ,Right now When , the calculation result is a constant phase angle of the amplitude , the vector phase angle is the initial phase angle of the grid voltage vector, and the amplitude is N times the grid voltage amplitude. After the inverse discrete Fourier transform, the fundamental positive sequence component contained in the input signal is obtained.

[0040] Preferably, the sampling period of the robust control system is optimized, including: determining the robust stability conditions of the mine variable frequency power supply system through Lyapunov stability theory; calculating the system robustness that meets the robust stability conditions; judging whether the sampling period can complete the numerical calculation within the sampling optimization calculation range based on the system robustness; if the sampling period can complete the numerical calculation within the sampling optimization calculation range, then entering the sampling period into the sampling period set; resetting the sampling period; screening out data with a shorter sampling period in the sampling period set, and recording it as the optimal sampling period.

[0041] Furthermore, based on Lyapunov stability theory, the robust stability conditions are determined, the system robustness is calculated and the optimal sampling period is screened out. The sampling period can be optimized systematically and targeted, so that the robust control system can be better configured in terms of the key parameter of the sampling period, thereby significantly improving the robustness of the mine-used variable frequency power supply system, enhancing its ability to cope with uncertain factors and interference, and ensuring the stable operation of the system.

[0042] Preferably, the determination of the robust stability condition satisfies the following formula 7; wherein, formula 7 is: ;in, is the performance index matrix, G is the transfer function matrix, Y is the system output matrix, and I is the identity matrix.

[0043] Furthermore, the mine frequency conversion system adopts a two-level networked robust control structure, which includes local primary control and remote secondary network control; local primary control includes local droop control, and local droop control includes droop control, voltage control and current control; voltage control and current control are implemented through PI controllers; remote secondary network control includes a remote robust controller, which realizes remote control of the mine frequency conversion power supply system through secondary compensation of frequency and voltage output by local droop control; the central controller calculates the corresponding reference values ​​of the micro-elements or energy storage units participating in the secondary control, and then sends them to the corresponding local controllers for execution.

[0044] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A method for improving the robustness of a mine-used variable frequency power supply system based on two-stage network compensation, characterized in that: include: Constructing a robust control system based on the mine-used variable frequency power supply system; Determining whether the mining variable frequency power supply system is stable by the robust control system; If it is determined that the mine-used variable frequency power supply system is unstable, performing secondary compensation on the mine-used variable frequency power supply system; The sampling period of the robust control system is optimized.

2. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 1, characterized in that: The robust control system is constructed according to the mine variable frequency power supply system, including: Constructing an input formula for the mine-used variable frequency power supply system based on the communication delay; Calculate the specific value of the communication delay and substitute it into the input formula; A remote robust controller is designed based on the mine variable frequency power supply system.

3. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 2, characterized in that: The input formula satisfies the following formula 1: Wherein, the formula 1 is: ； Among them, u(t) is the input, t is the time parameter, t m is the time of the mth sampling, is the communication delay, T s is the sampling period; The calculation of the communication delay satisfies the following formula 2: Wherein, the formula 2 is: ； Among them, m is the summation upper limit, k is the weight index, T send The time interval for sending data; The design of the remote robust controller satisfies the following formula 3: Wherein, the formula 3 is: ； Where K is the feedback gain matrix.

4. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 1, characterized in that: The determining whether the mining variable frequency power supply system is stable by the robust control system includes: determining a closed-loop system model under state response control of the robust control system; Setting the sampling period and sampling optimization calculation range of the robust control system; The asymptotic stability condition of the mine-used variable frequency power supply system is determined according to the Schur complement lemma, and whether the mine-used variable frequency power supply system is stable is judged.

5. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 4, characterized in that: The closed-loop system model satisfies the following formula 4: Wherein, the formula 4 is: ； Among them, x(k) is the state vector of the mine variable frequency power supply system at time k, A d is the state transfer matrix of the mine variable frequency power supply system, B 10 is the first input matrix, B 11 is the second input matrix, B2 is the third input matrix, z(k) is the output vector of the mine variable frequency power supply system at time k, C is the output matrix, D1K is the matrix related to the input, D2 is the matrix related to the interference, and w(k) is the vector group related to the interference.

6. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 4, characterized in that: The calculation of the asymptotic stability condition satisfies the following formula 5: Wherein, the formula 5 is: ; Wherein, Q is the first asymptotically stable matrix representing positive definiteness, and P is the second asymptotically stable matrix representing positive definiteness.

7. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 1, characterized in that: The secondary compensation of the mining variable frequency power supply system includes: The basic information of the power grid bus is determined by iterative Fourier transform detection method; Calculate the fundamental frequency information of the grid voltage; Uploading the basic information and the fundamental frequency information to the robust control system, and comparing them with the local droop control output to obtain a secondary compensation value; The quadratic compensation value is compensated to a local droop control output terminal through the robust control system.

8. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 7, characterized in that: The calculation of the fundamental frequency information satisfies the following formula 6: Wherein, the formula 6 is: ； in, ; ; , N is a natural number.

9. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 4, characterized in that: The optimizing the sampling period of the robust control system includes: The robust stability conditions of the mine variable frequency power supply system are determined by Lyapunov stability theory; Calculating the system robustness that satisfies the robust stability condition; Determining whether the sampling period can complete the numerical calculation within the sampling optimization calculation range according to the system robustness; If the sampling period can complete the numerical calculation within the sampling optimization calculation range, then the sampling period is entered into the sampling period set; Resetting the sampling period; The data with a shorter sampling period in the sampling period set is screened out and recorded as the optimal sampling period.

10. The method for improving the robustness of a mine-used variable frequency power supply system according to claim 9, characterized in that: The determination of the robust stability condition satisfies the following formula 7: Wherein, the formula 7 is: ； in, is the performance index matrix, G is the transfer function matrix, Y is the system output matrix, and I is the identity matrix.

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