Fault current control method, device and equipment of magnetic flux controllable reactor and medium

Abstract

The embodiment of the invention provides a fault current control method and device of a magnetic flux controllable reactor, equipment and a medium, and relates to the technical field of electric power. The method comprises the steps that primary side current and secondary side current of the magnetic flux controllable reactor are detected in real time, when it is determined that system current is unstable according to the primary side current and the secondary side current, target parameters are determined according to the primary side current, the secondary side current and an implicit function of the primary side current and the secondary side current of the magnetic flux controllable reactor, and the target parameters are variable parameters in the implicit function; and the implicit function represents a mathematical relationship between the primary side current and the secondary side current of the magnetic flux controllable reactor. And determining target delay time corresponding to the target parameter according to a mapping relation between the target parameter and the delay time. And finally, configuring the target delay time as the delay time of the magnetic flux controllable reactor. By means of the method, the problem that the fault current stability control effect is not ideal due to the fact that a lag angle exists between the primary side current and the secondary side current of the magnetic flux controllable reactor is solved.

Description

Technical Field

[0001] This application relates to the field of power technology, and in particular to a fault current control method, device, equipment and medium for a flux-controlled reactor. Background Technology

[0002] In order to regulate grid voltage, regulate grid power flow, and compensate for reactive power, the power grid system needs a reactor with variable impedance.

[0003] In existing methods for current stabilization control in power systems using flux-controlled reactors, a transformer with an air gap is used as the controllable reactor. Its primary side is connected in series with the power grid, and its secondary side is connected to a voltage-source inverter. Current stabilization is achieved by generating a secondary current that is related to the primary current. However, in actual power system operation, due to the inductive characteristics of the reactor, when the primary current changes, the secondary current does not immediately change synchronously, resulting in a certain time delay.

[0004] The existing method for current stabilization control of power systems through flux-controlled reactors does not take into account the lag angle between primary and secondary currents, resulting in unsatisfactory fault current stabilization control, which is an urgent technical problem to be solved. Summary of the Invention

[0005] This application provides a method, apparatus, device, and medium for controlling the fault current of a flux-controlled reactor, in order to solve the technical problem that the fault current stability control effect is not ideal due to the lag angle between the primary and secondary currents of the flux-controlled reactor.

[0006] In a first aspect, embodiments of this application provide a fault current control method for a flux-controlled reactor, applied to a control device. The control device is used to control a flux-controlled reactor in a power grid system, wherein the flux-controlled reactor is connected in series in the power grid system. The method includes:

[0007] The primary and secondary currents of the flux-controlled reactor are detected and acquired.

[0008] When the system current is determined to be unstable based on the primary side current and the secondary side current, a target parameter is calculated based on the primary side current, the secondary side current, and the implicit function of the current between the primary and secondary sides of the flux-controlled reactor. The target parameter is a variable parameter in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor.

[0009] Based on the predetermined mapping relationship between target parameters and delay time, the target delay time corresponding to the target parameters is determined;

[0010] The target delay time is configured as the delay time of the flux-controlled reactor.

[0011] In one possible implementation, the mapping relationship is determined based on the influence of the phase angle between the primary and secondary currents corresponding to different target parameters on the transfer function of the flux-controlled reactor;

[0012] The mapping relationship includes: multiple value ranges of the target parameter, and the delay time corresponding to each value range.

[0013] In one possible implementation, the implicit function is:

[0014]

[0015] in, This represents the primary current of the flux-controlled reactor. Indicates inverter tracking The generated current, α represents the target parameter, k represents the transformer turns ratio, θ represents the phase angle between the primary and secondary currents, e represents the natural constant, and j represents the imaginary unit.

[0016] In one possible implementation, before determining the target delay time corresponding to the target parameter based on the predetermined mapping relationship between the target parameter and the delay time, the method further includes:

[0017] Based on the equivalent circuit diagram of the flux-controlled reactor, the closed-loop transfer function of the flux-controlled reactor is obtained.

[0018] Based on the closed-loop transfer function, obtain the frequency domain transfer function and time domain transfer function of the delay element;

[0019] Based on the phase angle with different values, the frequency domain transfer function and the time domain transfer function determine the mapping relationship.

[0020] In one possible implementation, the closed-loop transfer function is:

[0021]

[0022] Where TF represents the closed-loop transfer function of the system, U S (s) represents the system voltage, I1(s) represents the primary current of the transformer, r1 represents the primary leakage resistance of the transformer, and r d The load resistance is represented by s, the complex frequency variable is represented by l. 1σ Indicates the leakage inductance on the primary side of the transformer, l d Indicates the load inductance, l s r represents the equivalent inductance of the power grid system.m The magnetizing resistance on the primary side of the transformer, l m This represents the magnetizing inductance on the primary side of the transformer.

[0023] In one possible implementation, the frequency domain transfer function is:

[0024]

[0025] Where G(s) represents the frequency domain transfer function of the delay element, and T1 represents the delay time.

[0026] In one possible implementation, the time-domain transfer function is:

[0027] H(θ)=e -jθ ;

[0028] Here, H(θ) represents the time-domain transfer function of the delay element.

[0029] Secondly, embodiments of this application provide a fault current control device for a flux-controlled reactor, comprising:

[0030] The first processing module is used to detect and acquire the primary side current and secondary side current of the flux-controlled reactor.

[0031] The second processing module is used to calculate target parameters based on the primary side current, the secondary side current, and the implicit function of the current between the primary and secondary sides of the flux-controlled reactor when the system current is determined to be unstable according to the primary side current and the secondary side current. The target parameters are variable parameters in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor.

[0032] The third processing module is used to determine the target delay time corresponding to the target parameter according to the pre-determined mapping relationship between the target parameter and the delay time;

[0033] The fourth processing module is used to configure the target delay time as the delay time of the flux-controlled reactor.

[0034] Thirdly, embodiments of this application provide a control device, including: a memory and a processor;

[0035] The memory stores computer-executed instructions;

[0036] The processor executes computer execution instructions stored in the memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0037] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0038] This application provides a fault current control method, apparatus, device, and medium for a flux-controlled reactor. By real-time detection of the primary and secondary currents of the flux-controlled reactor, when system current instability is determined based on the primary and secondary currents, a target parameter is determined according to the primary and secondary currents, and an implicit function relating them. The target parameter is a variable parameter within the implicit function, which represents the mathematical relationship between the primary and secondary currents of the flux-controlled reactor. Then, based on the mapping relationship between the target parameter and the delay time, a target delay time is determined. Finally, the target delay time is configured as the delay time of the flux-controlled reactor. This method effectively solves the technical problem of unsatisfactory fault current stability control due to the lag angle between the primary and secondary currents of the flux-controlled reactor, thus enhancing the stability and reliability of the power grid operation. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0040] Figure 1(a) is a circuit diagram of a flux-controlled electronic controller in the prior art;

[0041] Figure 1(b) is a schematic diagram of the T-type equivalent circuit of a flux-controlled electronic controller in the prior art;

[0042] Figure 2 A flowchart illustrating a fault current control method for a flux-controlled reactor provided in this application;

[0043] Figure 3(a) is a flowchart illustrating a fault current control method for a flux-controlled reactor provided in this application. Figure 2 ;

[0044] Figure 3(b) is a schematic diagram of the series equivalent circuit of a flux-controlled reactor provided in this application;

[0045] Figure 3(c) is a schematic diagram of the equivalent structure of a flux-controlled reactor in series according to this application;

[0046] Figure 3(d) is a schematic diagram of the series equivalent structure of a flux-controlled reactor provided in this application. Figure 2 ;

[0047] Figure 3(e) is a simulation circuit diagram based on the PSIM simulation model provided in this application;

[0048] Figure 3(f) is a schematic diagram of a system current waveform provided in this application;

[0049] Figure 3(g) is a schematic diagram of a system current waveform provided in this application. Figure 2 ;

[0050] Figure 3(h) is a schematic diagram of a system current waveform provided in this application.

[0051] Figure 3(i) shows a schematic diagram of a system current waveform provided in this application. Figure 4 ;

[0052] Figure 3(j) is a schematic diagram comparing the system current waveforms provided in this application;

[0053] Figure 3(k) shows a schematic diagram of a system current waveform provided in this application. Figure 5 ;

[0054] Figure 3(l) is a schematic diagram of a system current waveform provided in this application.

[0055] Figure 3(m) is a schematic diagram of a system current waveform provided in this application;

[0056] Figure 3(n) is a schematic diagram of a system current waveform provided in this application.

[0057] Figure 4 A schematic diagram of the fault current control device for a flux-controlled reactor provided in this application;

[0058] Figure 5 This is a schematic diagram of the structure of a control device provided in this application.

[0059] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0060] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0061] The application background of this application is explained as follows:

[0062] With the development of society and the economy, the number of various electrical devices is constantly increasing, placing higher demands on the power supply quality and stability of the power grid. To ensure that the power grid can stably and reliably supply power to users, it is necessary to effectively regulate the grid voltage, power flow, and reactive power. Flux-controlled reactors, due to their ability to change their impedance characteristics as needed, have become an ideal choice.

[0063] Figure 1(a) is a circuit diagram of a flux-controlled electric controller in the prior art, and Figure 1(b) is a T-type equivalent circuit diagram of a flux-controlled electric controller in the prior art. In existing methods for achieving stable current control in power systems through flux-controlled reactor regulation, a transformer with an air gap is used as the controllable reactor. As shown in Figure 1(a), assuming the number of turns AX on the primary side of the transformer (fluid-controlled electric controller) is N1 and the number of turns ax on the secondary side is N2, then the transformer turns ratio k = N1 / N2. Connecting the primary side of the transformer in series with the power grid generates a primary current of... By detecting the primary current of the transformer And use an inverter to track this current and generate a current. Will Reverse injection is applied to the secondary side of the transformer. As shown in Figure 1(b), yes The value converted to the primary side of the transformer, Because of the current injected into the secondary side through the inverter It tracks the primary side current. This means that the two satisfy a certain relationship: Where γ represents and The implicit function of the relation, γ≥0.

[0064] Z1=r1+jωl 1σ Z2′ represents the leakage impedance of the primary winding, Z2′=r2′+jωl 2σ Z' represents the leakage impedance referred from the secondary side to the primary side. m =r m +jωl m This represents the transformer's magnetizing impedance, where r1 and l 1σ R2′ and L represent the leakage resistance and leakage inductance on the primary side of the transformer, respectively. 2σ ′ represents the leakage resistance and leakage inductance of the transformer secondary side referred to the primary side, respectively; j represents the imaginary unit; ω represents the angular frequency; r m and l m These represent the magnetizing resistance and magnetizing inductance on the primary side of the transformer, respectively. Current is injected into both the primary and secondary sides of the transformer for magnetization, and the total magnetomotive force in its core... for: in, F1 represents the magnetomotive force (MF) induced by the injected current on the primary side of the transformer, and F2 represents the magnetomotive force induced by the injected current on the secondary side of the transformer. The voltage across the primary side of the transformer. for: Looking from the primary side of the transformer, the equivalent impedance of the transformer is: Z AX =Z1+(1-γ)Z m As can be seen from this equation, the impedance presented by the transformer is a variable, and its magnitude satisfies a certain relationship with γ. By changing the magnitude of the current injected into the secondary side of the transformer, i.e., the magnitude of γ, Z can be changed. AX The value of Z is used to achieve stepless adjustment of the primary impedance of the transformer. Table 1 shows the changes in Z as γ changes. AX The changes in the value of .

[0065] Table 1 Z AX The value of varies with γ

[0066]

[0067] In practical applications, γ can take specific values ​​to achieve different purposes. For example, in a fault current limiter, when γ = 1 during normal operation, Z... AX =Z1, because the leakage reactance is very small and has little impact on the system. When a fault occurs, control γ=0. This impedance is manifested as the excitation impedance. The impedance is very large and can be used to limit the fault current.

[0068] As described above, the primary side of the flux-controlled electronic controller is connected in series with the power grid, making the primary current directly related to the grid current. A voltage-source inverter is connected to the secondary side, generating a secondary current that has a specific relationship with the primary current, thus achieving stable control of the grid current. However, in the actual operation of a power system, due to the inductive characteristics of the air-gap transformer (inductive elements impede current changes), when the primary current changes, the magnetic field inside the transformer needs to be re-established and adjusted. This process takes time, resulting in a time delay in the secondary current; that is, there is a certain lag angle between the primary and secondary currents.

[0069] In summary, existing methods for current stabilization control in power systems using flux-controlled reactors do not fully consider the impact of the lag angle between primary and secondary currents. When a fault occurs in the power system, such as a short-circuit fault, the primary current changes drastically and instantaneously. The secondary current, which should respond promptly, cannot adjust as expected due to the lag angle, resulting in ineffective suppression and stabilization of the fault current. This exacerbates voltage drops and power flow distribution during the fault, increasing the risk of damage to grid equipment and potentially triggering a chain reaction that affects the safe and stable operation of the entire power system.

[0070] Therefore, solving the problem of unsatisfactory fault current stability control effect caused by the failure to consider the lag angle in the existing flux-controlled reactor regulation method has become an urgent technical problem to be solved in the power system field, and has important practical significance for improving the reliability and stability of the power system.

[0071] Based on the aforementioned technical problems, the inventors, in the process of researching fault current control methods based on flux-controlled reactors, discovered that by acquiring the primary and secondary currents of the flux-controlled reactor, and when determining that the system current is unstable, by combining the primary and secondary currents, as well as the specific relationship between the primary and secondary currents due to electromagnetic coupling characteristics and the stability control requirements of the power grid system, the lag angle / phase angle / delay time between the primary and secondary currents can be determined and configured as the delay time of the reactor. This compensates for the lag between the primary and secondary currents, effectively improving the current stability control effect. Based on this, this application provides a fault current control method, device, equipment, and medium for flux-controlled reactors.

[0072] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0073] Figure 2 A flowchart illustrating a fault current control method for a flux-controlled reactor provided in this application is shown in Figure 1. This method is applied to a control device used to control a flux-controlled reactor connected in series to a power grid system. Figure 2 As shown, the method includes:

[0074] S201: Detect and acquire the primary and secondary currents of the flux-controlled reactor.

[0075] In this step, the flux-controlled reactor uses a transformer with an air gap as its main body, including a primary winding and a secondary winding. The primary winding of the transformer is connected in series with the power grid. The current flowing through the primary winding of the flux-controlled reactor is the primary current, which serves as the input current and typically originates from the main power source of the power system. The current flowing through the secondary winding of the flux-controlled reactor, generated by the inverter tracking the primary current, is the secondary current; that is, this current is generated in the secondary winding by electromagnetic induction from the primary current.

[0076] For example, by connecting current sensors, such as Hall effect current sensors or Rogowski coils, in series at the output terminals of both the primary and secondary windings, the current sensors can convert the measured current signal into a proportional voltage or digital signal. This signal is then transmitted to the control unit via a data acquisition module, thereby enabling real-time detection and acquisition of the primary and secondary currents. By acquiring the primary and secondary currents of the flux-controlled reactor in real time, the dynamic changes in the currents on both sides of the reactor can be monitored, providing a direct basis for determining the stability of the system current.

[0077] S202: When the system current is determined to be unstable based on the primary current and the secondary current, the target parameter is calculated based on the implicit function of the primary current, the secondary current, and the current between the primary and secondary sides of the flux-controlled reactor. The target parameter is a variable parameter in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor.

[0078] In this step, system current instability refers to the deviation of parameters such as the amplitude, frequency, or phase of the current in the power system from the normal stable range, resulting in abnormal states such as continuous fluctuations, sudden changes, or oscillations. In one optional implementation, the stability of the system current depends on the coordination of the primary-side current (grid-side input) and the secondary-side current (inverter control output). If the deviation between the effective value of the system current and the detected / calculated value of the system current exceeds a set limit and persists or even diverges over time, it indicates that the coordination between the primary-side current and the secondary-side current has been disrupted, and they cannot effectively cooperate to maintain system current stability.

[0079] As shown in the embodiment of Figure 1, the secondary side current is generated by the inverter tracking the primary side current. In other words, there is a certain relationship between the secondary side current and the primary side current. However, due to the inductive characteristics of the air-gap transformer itself during the actual operation of the power system, there is a certain lag angle (phase angle / delay time) between the primary and secondary currents.

[0080] Therefore, in one possible implementation, the relationship between the secondary current and the primary current, i.e., the implicit function of the current between the primary and secondary sides of the flux-controlled reactor, can be expressed as:

[0081]

[0082] in, This represents the primary current of the flux-controlled reactor. Indicates inverter tracking The generated current, α represents the target parameter, k represents the transformer turns ratio, θ represents the phase angle between the primary and secondary currents, e represents the natural constant, and j represents the imaginary unit.

[0083] At this moment, looking into the primary side of the transformer, the impedance Z of the flux-controlled reactor is... AX for:

[0084]

[0085] Where Z1 represents the leakage impedance of the primary winding, Z m This represents the excitation impedance of the transformer.

[0086] Expanding equation (2) according to Euler's formula, we can express it as:

[0087] Z AX =Z1+Z m (1-α·cosθ+jα·sinθ) (3)

[0088] α, as the target parameter, directly determines the secondary current. For primary side current The tracking and compensation intensity. For example, if α = 0, then Approaching 0 means that the secondary inverter does not inject compensation current, the reactor is close to a pure inductor, the reactor is equivalent to no-load operation, and is not affected by the lag angle θ between the primary and secondary currents. Therefore, the impedance seen from the primary side is the sum of leakage impedance and excitation impedance, and the impedance characteristics are resistive and inductive.

[0089] For example, if α = 1, the impedance seen from the primary side can be expressed as:

[0090]

[0091] Among them, x m x1 represents the excitation reactance, and x1 represents the leakage impedance of the primary coil.

[0092] Z AX The real part can be represented as: Re(Z) AX )=(r1+r m )-Zm cos(θ-ψ m Z AX The imaginary part can be represented as: Im(Z) AX )=(x1+x m )+Z m sin(θ-ψ m ), where ψ m =arctan(x m / r m (r1) represents the impedance angle of the excitation winding. For a transformer, under normal circumstances, r1 and r2 are... m The value is much smaller than Z m And x m and Z m The value of is equivalent, therefore, ψ m =arctan(x m / r m )≈90°. Therefore, Z AX The real part can be simplified to: Re(Z) AX )≈-x m sinθ, Z AX The imaginary part can be simplified to: Im(Z) AX )≈-x m (1-cosθ). It's understandable that when 0 < θ < 180°, Re(Z) AX ) < 0; when 180° < θ < 360°, Re(Z) AX ) > 0; while Im(Z) AX The value is always greater than 0. Therefore, we can conclude that:

[0093]

[0094] As can be seen from the above, different target parameters α correspond to different operating states of the flux-controlled reactor. The mathematical relationship between the primary and secondary currents of the flux-controlled reactor is precisely defined. By determining the target parameter α, the equivalent impedance of the reactor can be actively adjusted to flexibly adapt to the grid demand. This allows the reactor to switch operating states in scenarios such as normal operation and fault current limiting, thereby achieving precise intervention in grid voltage regulation, power flow control, and reactive power compensation. This compensates for control defects caused by the lag between the primary and secondary currents, improves the system current stability control effect, and enhances the stability and reliability of grid operation.

[0095] S203: Determine the target delay time corresponding to the target parameter based on the pre-determined mapping relationship between the target parameter and the delay time.

[0096] In this step, the delay time and hysteresis angle are both physical quantities that describe the phase shift between the primary and secondary currents, and there is a relationship between them: θ = 180° / π × ωT1 = 180° / π × 2πfT1 = 360°fT1.

[0097] According to equation (5), if θ = 180°, that is, when the delay is half a fundamental cycle, the reactor's impedance exhibits a large excitation impedance. When connected in the line, there will be a large fundamental voltage drop across the reactor, affecting the normal operation of the load. Moreover, depending on the size of the delay angle, the reactor can exhibit negative resistance characteristics. When connected to a resistive-capacitive load, resonance may occur, causing the system current to increase and potentially leading to malfunction of the relay protection device. It is evident that the lag angle has a significant impact on the normal operation of the reactor.

[0098] The mapping relationship between the target parameter and the delay time refers to the correspondence between the target parameter α and the delay time T1 obtained through extensive testing in previous research and experiments (fixing the target parameter α and monitoring the impact of the corresponding delay angle / delay time on the stability of the system current). Once the target parameter α is determined, this mapping relationship is invoked to determine the target delay time required for the current target parameter α, providing a basis for subsequent configuration of reactor delay and compensation for the lag angle of the primary and secondary currents.

[0099] S204: Configure the target delay time as the delay time of the flux-controlled reactor.

[0100] In this step, the target delay time is configured as the delay time of the flux-controlled reactor. This can be done by software settings, hardware command issuance, or other means, and written into the control unit or related adjustment module of the flux-controlled reactor so that its actual operation adopts this delay time.

[0101] By configuring the target delay time to the flux-controlled reactor, the secondary current tracks the primary current, and the phase difference is adapted according to the delay time. This compensates for the current lag caused by the inherent inductance characteristics, enabling precise coordination between the primary and secondary currents. This optimizes the reactor's regulation of the grid current and improves the system's current stability control.

[0102] The fault current control method for flux-controlled reactors provided in this application embodiment detects the primary and secondary currents of the flux-controlled reactor in real time. When the system current is unstable, a target parameter is determined based on the implicit function relationship between the primary and secondary currents. This parameter directly affects the tracking and compensation strength of the secondary current on the primary current. A target delay time is determined according to the mapping relationship between the target parameter and the delay time. Finally, the target delay time is configured as the delay time of the flux-controlled reactor. This method effectively solves the technical problem of unsatisfactory fault current stability control due to the lag angle between the primary and secondary currents of the flux-controlled reactor, thus enhancing the stability and reliability of the power grid operation.

[0103] Figure 3(a) is a flowchart illustrating a fault current control method for a flux-controlled reactor provided in this application. Figure 2 As shown in Figure 3(a), in Figure 2 Based on the embodiment, in S203: before determining the target delay time corresponding to the target parameter according to the predetermined mapping relationship between the target parameter and the delay time, the fault current control method of the flux-controlled reactor further includes:

[0104] S301: Obtain the closed-loop transfer function of the flux-controlled reactor based on the equivalent circuit diagram of the flux-controlled reactor.

[0105] Figure 3(b) is a schematic diagram of the equivalent circuit of a flux-controlled reactor in series according to this application, and Figure 3(c) is a schematic diagram of the equivalent structure of a flux-controlled reactor in series according to this application. When the flux-controlled reactor is connected in series between the system and the load, according to the equivalent circuit diagram and equivalent structure diagram shown in Figures 3(b) and 3(c), the closed-loop transfer function of the system can be obtained as follows:

[0106]

[0107] Where TF represents the closed-loop transfer function of the system, U S (s) represents the system voltage, I1(s) represents the primary current of the transformer, and U S Indicates the voltage of the power grid system, l s r represents the equivalent inductance of the power grid system. d and l d Let r1 and l represent the load resistance and inductance, respectively. 1σ R2′ and L represent the leakage resistance and leakage inductance on the primary side of the transformer, respectively. 2σ ′ represents the leakage resistance and leakage inductance of the transformer secondary side referred to the primary side, respectively. m and l m These represent the magnetizing resistance and magnetizing inductance on the primary side of the transformer, respectively, and s represents the complex frequency variable.

[0108] S302: Based on the closed-loop transfer function, obtain the frequency domain transfer function and time domain transfer function of the delay element.

[0109] In one possible implementation, the frequency domain transfer function is: Where G(s) represents the frequency domain transfer function of the delay element, and T1 represents the delay time.

[0110] In another possible implementation, the time-domain transfer function is H(θ) = e -jθ , where H(θ) represents the time-domain transfer function of the delay element.

[0111] Compare the time-domain transfer function e of the delay element -jθ Frequency domain transfer function Substituting s = jω into the equation, we get θ = ωT1, where θ is in radians, T1 is in seconds, and ω = 2πf.

[0112] frequency domain transfer function Expanded using Taylor series, it is as follows:

[0113]

[0114] If the delay time is small, i.e., T1 is small, then equation (6) can be obtained by taking only the first two terms:

[0115]

[0116] If the delay time is large, the time-domain transfer function e of the delay element... -jθ In this circuit, the phase angle θ∈[0,2π] corresponds to T1∈[0,0.02] over one power frequency cycle. We need to find a circuit that can perform a 0 to 360° phase shift with lag. Based on the knowledge of equal-amplitude phase-shifting circuits, we know that:

[0117]

[0118] Where A(s) represents the full-range shift model, and τ represents the time constant.

[0119] Gain | A V |=1, phase shift φ=-4arctan(ωτ). When τ=0, φ=0; when τ=+∞ or when ωτ is sufficiently large, φ=-2π. The lag angle value can be changed by changing the magnitude of the time constant τ. According to equation (8), when θ∈[0,π], A1(s) is equivalent to When θ∈[π,2π], A2(s) is equivalent.

[0120]

[0121] Where A1(s) represents the small delay approximation model, A2(s) represents the large delay approximation model, and τ1 and τ2 both represent time constants.

[0122] S303: Determine the mapping relationship based on the phase angle, frequency domain transfer function, and time domain transfer function for different values.

[0123] Figure 3(d) is a schematic diagram of the series equivalent structure of a flux-controlled reactor provided in this application. Figure 2 In one possible implementation, when the phase angle θ∈[0,π], A1(s) is equivalent. The equivalent structure diagram of the flux-controlled reactor at this point is shown in Figure 3(d). The closed-loop transfer function of the system is:

[0124]

[0125] Where a0, a1, and a2 are all constants, and a0 = [l 1σ +l d +l S +(1+α)l m ]τ1, a1=[r1+r d +(1+α)r m ]τ1+l 1σ +l d +l S +(1-α)l m a2 = r1 + r d +(1-α)r m The characteristic equation is D(s) = a0s. 2 +a1s+a2. According to the Hurwitz stability criterion, the necessary and sufficient condition for the stability of a linear system is: the principal determinant Δ2 formed by the coefficients of the system's characteristic equation and its ordered principal minors Δ i (i=1) All positive can be represented as:

[0126]

[0127] This can be equivalent to:

[0128]

[0129] When l m >r m At τ1, the objective parameter α satisfies:

[0130]

[0131] When l m <r m At τ1, the objective parameter α satisfies:

[0132]

[0133] It is worth noting that τ1≠T1, τ1=tan(9T1) / ω, T1∈(0,10). Here, T is in milliseconds, τ1 is in seconds, and ω is in radians per second (rad / s).

[0134] Regardless of the value of τ1, the target parameter α = 1 can satisfy equations (13) and (14), that is, the system current is definitely stable when α = 1, that is, the reactor based on the fundamental magnetic flux complete compensation can definitely control the system current to achieve stability.

[0135] In another possible implementation, when the phase angle θ∈[π,2π], A2(s) is equivalent. At this point, the closed-loop transfer function of the system is:

[0136]

[0137] Where b0, b1, and b2 are all constants, and b0 = [l 1σ +l d +l S +(1-α)l m ]τ2,b1=[r1+r d +(1-α)r m ]τ2+[l 1σ +l d +l S +(1+α)l m b2 = r1 + r d +(1+α)r m The characteristic equation is D(s) = b0s. 2 +b1s+b2.

[0138] Similarly, according to the Hurwitz stability criterion, we can obtain:

[0139] When l m >r m At τ2, the objective parameter α satisfies:

[0140]

[0141] When l m <r m At τ2, the objective parameter α satisfies:

[0142]

[0143] It is worth noting that τ2≠T1, τ1=tan(9T1-90°)ω,T1∈(10,20).

[0144] Regardless of the value of τ2, the target parameter α = 1 can satisfy equations (16) and (17), that is, the system current is definitely stable when α = 1, that is, the reactor based on the complete compensation of the fundamental magnetic flux can definitely control the system current to achieve stability.

[0145] Figure 3(e) shows a simulation circuit diagram based on a PSIM simulation model provided in this application. In one possible implementation, the mapping relationship is determined based on the influence of the phase angle between the primary and secondary currents corresponding to different target parameters on the transfer function of the flux-controlled reactor. The mapping relationship includes multiple value ranges of the target parameters and the delay time corresponding to each value range. As shown in Figure 3(e), in a specific implementation of this scheme, the mapping relationship is determined based on the PSIM (Power Simulation) simulation model, according to the phase angle, frequency domain transfer function, and time domain transfer function with different values. The main parameters of the simulation circuit are shown in Table 2.

[0146] Table 2 Main parameters of the simulation circuit

[0147] parameter Numerical illustrate <![CDATA[U S / V]]> 220 RMS value of power supply voltage <![CDATA[l1 / mH]]> 50 Transformer primary side self-inductance <![CDATA[l2 / mH]]> 50 Transformer secondary self-inductance <![CDATA[l m / mH]]> 49 Transformer mutual inductance <![CDATA[r d / Oh]]> 10 Load resistance value <![CDATA[l d / mH]]> 10 Load inductance value k 1:1 Transformer turns ratio

[0148] Figure 3(f) is a schematic diagram of a system current waveform provided in this application. In a specific implementation of this scheme, when the target parameter α = 0, the effective value of the system current is 10.47A and the calculated value is 10.31A. At this time, no matter how the delay time T1 is changed, as shown in Figure 3(f), the system current remains stable.

[0149] Figure 3(g) is a schematic diagram of a system current waveform provided in this application. Figure 2 In one specific implementation of this scheme, when the target parameter α = 1 and the delay time T1 = 0 (i.e., the phase difference θ = 0°), the effective value of the system current is 21.08A and the calculated value is 20.99A. At this time, as shown in Figure 3(g), the system current remains stable.

[0150] Figure 3(h) is a schematic diagram of the system current waveform provided in this application. In a specific implementation of this scheme, when the target parameter α = 1 and the delay time T1 = 5ms (i.e., phase difference θ = 90°), the effective value of the system current is 11.84A, and the calculated value is 11.40A. Clearly, the circuit structure parameters remain unchanged; changing the delay time alters the equivalent impedance of the transformer, thus changing the current. At this point, as shown in Figure 3(h), the system current remains stable.

[0151] Figure 3(i) shows a schematic diagram of a system current waveform provided in this application. Figure 4Figure 3(j) is a schematic diagram comparing the system current waveforms provided in this application. In a specific implementation of this scheme, when the target parameter α = 1 and the delay time T1 = 10ms (i.e., phase difference θ = 180°), the effective value of the system current is 6.41A, and the calculated value is 6.22A. At this time, as shown in Figure 3(i), the system current remains stable. According to theoretical analysis, the system current waveform corresponding to the target parameter α = -1 and the delay time T1 = 0ms (i.e., phase difference θ = 0°) is consistent with that in Figure 3(i). As shown in Figure 3(j), the schematic diagram of the system current waveform corresponding to the target parameter α = 1 and the delay time T1 = 10ms is basically the same as that corresponding to the target parameter α = -1 and the delay time T1 = 0ms.

[0152] In one possible implementation, when the target parameter satisfies -1 ≤ α ≤ 1, the delay time has no effect on the stability of the system current, and the system current is guaranteed to be stable. According to stability analysis, when the delay time T1 = 0 ms and α < 1.225, the system current remains stable.

[0153] Figure 3(k) shows a schematic diagram of a system current waveform provided in this application. Figure 5 In one specific implementation of this scheme, when the target parameter α = 1.224 and the delay time T1 = 0ms (i.e., the phase difference θ = 0°), as shown in Figure 3(k), the system current remains stable.

[0154] Figure 3(l) is a schematic diagram of a system current waveform provided in this application. In a specific implementation of this scheme, when the target parameter α = 1.226 and the delay time T1 = 0ms (i.e., the phase difference θ = 0°), as shown in Figure 3(l), the deviation between the effective value of the system current and the calculated value of the system current exceeds the set limit and continues to exist or even diverges with time, and the system current is in an unstable state.

[0155] Figure 3(m) is a schematic diagram of a system current waveform provided in this application (seventh example), and Figure 3(n) is a schematic diagram of a system current waveform provided in this application (eighth example). In a specific implementation of this scheme, when the target parameter α = 1.226, i.e., the system current is in an unstable state, according to the predetermined mapping relationship between the target parameter and the delay time, if the target delay time corresponding to the target parameter α = 1.226 is determined to be T1 = 1ms, then the effective value of the system current is 52.40A, as shown in Figure 3(m), and the system current remains stable. If the target delay time corresponding to the target parameter α = 1.226 is determined to be T1 = 5ms, then the effective value of the system current is 11.10A, as shown in Figure 3(n), and the system current remains stable.

[0156] The fault current control method for flux-controlled reactors provided in this application obtains the closed-loop transfer function of the flux-controlled reactor, analyzes its equivalent circuit diagram, determines the reactor's dynamic behavior in the system, and uses the frequency domain transfer function and time domain transfer function to analyze the impact of the delay element on the system current, establishing a mapping relationship between target parameters and delay time. By adjusting the target parameters and delay time, this fault current control method for flux-controlled reactors can actively regulate the equivalent impedance of the reactor to adapt to different grid demands, achieving precise intervention in grid voltage regulation, power flow control, and reactive power compensation. Through the above method, the stability of the system current is effectively controlled under different target parameters and delay times, and the system current remains stable even when there is a lag angle between the primary and secondary currents of the flux-controlled reactor or when the load changes.

[0157] Figure 4 A schematic diagram of the fault current control device for a flux-controlled reactor provided in this application is shown below. Figure 4 As shown, the fault current control device 40 for the flux-controlled reactor provided in this embodiment includes:

[0158] The first processing module 401 is used to detect and acquire the primary side current and secondary side current of the flux-controlled reactor.

[0159] The second processing module 402 is used to calculate the target parameters based on the primary current, secondary current, and implicit function of the current between the primary and secondary sides of the flux-controlled reactor when the system current is determined to be unstable based on the primary current and secondary current. The target parameters are the variable parameters in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor.

[0160] The third processing module 403 is used to determine the target delay time corresponding to the target parameter according to the pre-determined mapping relationship between the target parameter and the delay time;

[0161] The fourth processing module 404 is used to configure the target delay time as the delay time of the flux-controlled reactor.

[0162] In one possible implementation, the mapping relationship is determined based on the influence of the phase angle between the primary and secondary currents corresponding to different target parameters on the transfer function of the flux-controlled reactor.

[0163] The mapping relationship includes: multiple value ranges of the target parameter, and the delay time corresponding to each value range.

[0164] In one possible implementation, the implicit function is:

[0165]

[0166] in, This represents the primary current of the flux-controlled reactor. Indicates inverter tracking The generated current, α represents the target parameter, k represents the transformer turns ratio, θ represents the phase angle between the primary and secondary currents, e represents the natural constant, and j represents the imaginary unit.

[0167] In one possible implementation, the fault current control device 40 of the flux-controlled reactor further includes a fifth processing module 405, used for:

[0168] Based on the equivalent circuit diagram of the flux-controlled reactor, the closed-loop transfer function of the flux-controlled reactor is obtained.

[0169] Based on the closed-loop transfer function, obtain the frequency domain transfer function and time domain transfer function of the delay element;

[0170] Based on the phase angle with different values, the frequency domain transfer function and the time domain transfer function are used to determine the mapping relationship.

[0171] In one possible implementation, the closed-loop transfer function is:

[0172]

[0173] Where TF represents the closed-loop transfer function of the system, U S (s) represents the system voltage, I1(s) represents the primary current of the transformer, r1 represents the primary leakage resistance of the transformer, and r d The load resistance is represented by s, the complex frequency variable is represented by l. 1σ Indicates the leakage inductance on the primary side of the transformer, l d Indicates the load inductance, l s r represents the equivalent inductance of the power grid system. m The magnetizing resistance on the primary side of the transformer, l m This represents the magnetizing inductance on the primary side of the transformer.

[0174] In one possible implementation, the frequency domain transfer function is:

[0175]

[0176] Where G(s) represents the frequency domain transfer function of the delay element, and T1 represents the delay time.

[0177] In one possible implementation, the time-domain transfer function is:

[0178] H(θ)=e -jθ ;

[0179] Here, H(θ) represents the time-domain transfer function of the delay element.

[0180] The fault current control device for the flux-controlled reactor provided in this embodiment can execute the method provided in the above-described method embodiment. Its implementation principle and technical effect are similar, and will not be described again in this embodiment.

[0181] Figure 5 This is a schematic diagram of the structure of a control device provided in this application. Figure 5 As shown, the control device 50 provided in this embodiment includes at least one processor 501 and a memory 502. Optionally, the control device 50 further includes a communication component 503. The processor 501, memory 502, and communication component 503 are connected via a bus 504.

[0182] In a specific implementation, at least one processor 501 executes computer execution instructions stored in memory 502, causing at least one processor 501 to perform the above-described method.

[0183] The specific implementation process of processor 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0184] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0185] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0186] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0187] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0188] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random-Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0189] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an application-specific integrated circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0190] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0191] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0192] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0193] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0194] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0195] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A fault current control method for a flux-controlled reactor, characterized in that, The method is applied to control equipment used to control a flux-controlled reactor in a power grid system, wherein the flux-controlled reactor is connected in series in the power grid system. The primary and secondary currents of the flux-controlled reactor are detected and acquired. When the system current is determined to be unstable based on the primary side current and the secondary side current, a target parameter is calculated based on the primary side current, the secondary side current, and the implicit function of the current between the primary and secondary sides of the flux-controlled reactor. The target parameter is a variable parameter in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor. Based on the predetermined mapping relationship between target parameters and delay time, the target delay time corresponding to the target parameters is determined; The target delay time is configured as the delay time of the flux-controlled reactor.

2. The method according to claim 1, characterized in that, The mapping relationship is determined based on the influence of the phase angle between the primary and secondary currents corresponding to different target parameters on the transfer function of the flux-controlled reactor; The mapping relationship includes: multiple value ranges of the target parameter, and the delay time corresponding to each value range.

3. The method according to claim 1 or 2, characterized in that, The implicit function is: in, This represents the primary current of the flux-controlled reactor. Indicates inverter tracking The generated current, α represents the target parameter, k represents the transformer turns ratio, θ represents the phase angle between the primary and secondary currents, e represents the natural constant, and j represents the imaginary unit.

4. The method according to claim 3, characterized in that, Before determining the target delay time corresponding to the target parameter based on the predetermined mapping relationship between the target parameter and the delay time, the method further includes: Based on the equivalent circuit diagram of the flux-controlled reactor, the closed-loop transfer function of the flux-controlled reactor is obtained. Based on the closed-loop transfer function, obtain the frequency domain transfer function and time domain transfer function of the delay element; Based on the phase angle with different values, the frequency domain transfer function and the time domain transfer function determine the mapping relationship.

5. The method according to claim 4, characterized in that, The closed-loop transfer function is: Where TF represents the closed-loop transfer function of the system, U S (s) represents the system voltage, I1(s) represents the primary current of the transformer, r1 represents the primary leakage resistance of the transformer, and r d The load resistance is represented by s, the complex frequency variable is represented by l. 1σ Indicates the leakage inductance on the primary side of the transformer, l d Indicates the load inductance, l s r represents the equivalent inductance of the power grid system. m The magnetizing resistance on the primary side of the transformer, l m This represents the magnetizing inductance on the primary side of the transformer.

6. The method according to claim 4, characterized in that, The frequency domain transfer function is: Where G(s) represents the frequency domain transfer function of the delay element, and T1 represents the delay time.

7. The method according to claim 4, characterized in that, The time-domain transfer function is: H(θ)=e -jθ ; Here, H(θ) represents the time-domain transfer function of the delay element.

8. A fault current control device for a flux-controlled reactor, characterized in that, include: The first processing module is used to detect and acquire the primary side current and secondary side current of the flux-controlled reactor. The second processing module is used to calculate target parameters based on the primary side current, the secondary side current, and the implicit function of the current between the primary and secondary sides of the flux-controlled reactor when the system current is determined to be unstable according to the primary side current and the secondary side current. The target parameters are variable parameters in the implicit function, which is used to represent the mathematical relationship between the current between the primary and secondary sides of the flux-controlled reactor. The third processing module is used to determine the target delay time corresponding to the target parameter according to the pre-determined mapping relationship between the target parameter and the delay time; The fourth processing module is used to configure the target delay time as the delay time of the flux-controlled reactor.

9. A control device, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1 to 7.

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