阅读说明：本技术 实现远端电压精确控制的电路、方法、系统及存储介质 (Circuit, method, system and storage medium for realizing remote voltage accurate control ) 是由 张东来 方明珠 刘明雨 高伟 于 2021-06-18 设计创作，主要内容包括：本发明公开一种实现远端电压精确控制的线缆电阻检测电路、检测方法,基于所述线缆电阻检测电路的远端电压精确控制方法、系统及存储介质,该线缆电阻检测电路包括：包括第一开关、线缆电阻检测回路和辅助电容,其中,所述辅助电容并联在长线缆末端,所述第一开关串接在电源输出端,所述线缆电阻检测回路并接在所述第一开关电源输出端,所述线缆电阻检测回路包括电压检测电路、电流采样电路、锁相环和第二开关,电压检测电路、电流采样电路的输出端分别与锁相环输入端相连,所述锁相环输出端输出正弦电压信号,并通过第二开关注入到线缆源端,锁相环对设定正弦电压信号进行频率锁定。本发明能够对线缆末端电压精确控制。(The invention discloses a cable resistance detection circuit and a detection method for realizing remote voltage accurate control, and the remote voltage accurate control method, system and storage medium based on the cable resistance detection circuit, the cable resistance detection circuit comprises: including first switch, cable resistance detection circuit and auxiliary capacitance, wherein, auxiliary capacitance connects in parallel at long cable end, first switch concatenates at power output end, cable resistance detection circuit connects in parallel first switching power output end, cable resistance detection circuit includes voltage detection circuit, current sampling circuit, phase-locked loop and second switch, and voltage detection circuit, current sampling circuit's output link to each other with the phase-locked loop input respectively, phase-locked loop output sinusoidal voltage signal to inject into the cable source end through the second switch, the phase-locked loop carries out the frequency locking to setting for sinusoidal voltage signal. The invention can accurately control the terminal voltage of the cable.)

1. Realize cable resistance detection circuit of accurate control of distal end voltage, its characterized in that: including first switch, cable resistance detection return circuit and auxiliary capacitance, wherein, auxiliary capacitance connects in parallel at long cable end, first switch with cable resistance detection return circuit all sets up at long cable source end, wherein, first switch concatenates at power output end, cable resistance detection return circuit connects in parallel first switch power output end, cable resistance detection return circuit includes voltage detection circuit, current sampling circuit, phase-locked loop and second switch, voltage detection circuit, current sampling circuit are used for gathering the voltage and the electric current of cable source end respectively, and its output links to each other with the phase-locked loop input respectively, phase-locked loop output initial frequency is f_refAnd when the phase difference between the sinusoidal voltage signal injected from the cable source end and the cable response current is 0, the phase-locked loop performs frequency locking on the sinusoidal voltage signal output by the phase-locked loop.

2. The cable resistance detection circuit according to claim 1, wherein: the phase-locked loop comprises a phase discriminator, a loop filter and a voltage-controlled oscillator which are sequentially arranged according to signals, wherein the voltage-controlled oscillator outputs an initial frequency f_refThe sinusoidal voltage signal is injected into the source end of the long cable, the sinusoidal voltage excitation and the cable response current are sampled,and the phase detector is used for carrying out phase monitoring, converting the detected phase difference signal into a voltage signal to be output, and processing the voltage signal by the loop filter to form a control voltage of the voltage-controlled oscillator so as to adjust the frequency of a sinusoidal voltage signal output by the voltage-controlled oscillator, wherein when the phase difference is 0, the phase-locked loop is used for carrying out frequency locking on the sinusoidal voltage signal output by the voltage-controlled oscillator.

3. The detection method of the cable resistance detection circuit according to claim 2, characterized in that: the method comprises the following steps:

s1: opening the first switch S1, closing the second switch S2, and injecting a sinusoidal voltage with a certain frequency into the cable by using a voltage-controlled oscillator;

s2: detecting the phases of the sinusoidal voltage excitation and the cable response current;

s3: judging whether the phase difference between the sine voltage excitation and the cable response current is 0 or not, if so, executing step S4, if not, converting the phase difference into a voltage quantity, and adjusting the frequency of the sine voltage output by the voltage-controlled oscillator until the phase difference is 0;

s4: locking the frequency of sinusoidal voltage output by the voltage-controlled oscillator, wherein the frequency is the resonant frequency of the cable inductor and the auxiliary capacitor;

s5: and under the frequency, acquiring the resistance value of the cable according to the sinusoidal voltage value and the current value of the cable at the same time.

4. The method for precisely controlling the voltage at the far end comprising the detection method of claim 3, wherein after obtaining the resistance value of the cable, the method further comprises:

step S6: opening the second switch S2 and closing the first switch S1 according to v_o(t)＝V_L+i_line(t)R_lineAnd carrying out closed-loop control on the output voltage of the voltage source to realize accurate regulation of the voltage at the tail end of the cable, wherein v_o(t) the voltage, V, of the source end of the cable which needs to be output at the moment t_LDesired input voltage for the load system, R_lineFor the cable voltage value, i, obtained in step S5_line(t) is the current value of the cable at time t.

5. The method for precisely controlling the voltage at the far end comprising the detection method of claim 3, wherein after obtaining the resistance value of the cable, the method further comprises: and step A, disconnecting the second switch S2, closing the first switch S1, dynamically compensating the terminal voltage of the cable according to the loss voltage of the cable, performing closed-loop control on the output voltage of the voltage source, and realizing accurate regulation of the terminal voltage of the cable, wherein the loss voltage of the cable is the product of the current value at the moment t and the voltage value of the cable obtained in the step S5.

6. A remote power transmission cable termination voltage control system, the system comprising: memory, a processor, and a remote power cable termination voltage control program stored on the memory, which when invoked by the processor performs the steps of the method according to claim 4 or 5.

7. A computer readable storage medium storing a long distance power cable end voltage control program which when invoked by a processor performs the steps of the method according to claim 4 or 5.

Technical Field

The invention relates to the technical field of cable impedance detection, in particular to a cable resistance detection circuit and a detection method for realizing remote voltage accurate control, and further relates to a remote voltage accurate control method, a system and a storage medium comprising the detection method.

Background

Cables used for long distance power transmission have a non-negligible resistance, so the far end load terminal voltage or the secondary power input voltage of the power supply will be less than the actual output voltage of the power supply. Especially, in low-voltage and high-current application occasions, the voltage drop caused by the resistance of the cable is large, and the problem that the load at the far end is under-voltage or the normal work of a secondary power supply is influenced exists.

The existing far-end cable resistance detection method mainly comprises the steps of connecting a large enough capacitor in parallel at the tail end of a cable to realize low alternating current impedance at a load end, measuring voltage change generated due to line resistance by continuously modulating current to a load system, and calculating to obtain a cable resistance value so as to perform cable voltage drop compensation. The method has higher requirements on the capacitance value of the capacitor in order to ensure lower alternating current impedance of a load end, and the detection precision of the cable resistance is influenced by the reduction of the capacitance value of the capacitor along with the service life.

Disclosure of Invention

The invention aims to solve the problem of voltage reduction caused by a long-distance power transmission cable, and provides a cable resistance detection circuit, a detection method, a remote voltage accurate control method, a system and a storage medium for realizing remote voltage accurate control, aiming at realizing remote accurate control on the terminal voltage of a cable.

In order to achieve the above object, the present invention provides a cable resistance detection circuit for realizing precise control of a far-end voltage, which includes a first switch, a cable resistance detection circuit and an auxiliary capacitor, wherein the auxiliary capacitor is connected in parallel to a tail end of a long cable, the first switch and the cable resistance detection circuit are both disposed at a source end of the long cable, the first switch is connected in series to a power output end, the cable resistance detection circuit is connected in parallel to a power output end of the first switch, and the cable resistance detection circuit includes a voltage detection circuitThe cable source end voltage detection circuit and the current sampling circuit are respectively used for collecting voltage and current of a cable source end, output ends of the voltage detection circuit and the current sampling circuit are respectively connected with input ends of the phase-locked loops, and output initial frequency of the phase-locked loops is f_refAnd when the phase difference between the sinusoidal voltage signal injected from the cable source end and the cable response current is 0, the phase-locked loop performs frequency locking on the sinusoidal voltage signal output by the phase-locked loop.

The further technical scheme of the invention is that the phase-locked loop comprises a phase discriminator, a loop filter and a voltage-controlled oscillator which are sequentially arranged according to signals, wherein the initial output frequency of the voltage-controlled oscillator is f_refThe sinusoidal voltage signal is injected into the source end of the long cable, sinusoidal voltage excitation and cable response current are sampled, phase monitoring is carried out through the phase discriminator, the phase discriminator converts the detected phase difference signal into a voltage signal to be output, the voltage signal is processed through the loop filter to form control voltage of the voltage-controlled oscillator, therefore, the frequency of the sinusoidal voltage signal output by the voltage-controlled oscillator is adjusted, and when the phase difference is 0, the phase-locked loop carries out frequency locking on the sinusoidal voltage signal output by the voltage-controlled oscillator.

The invention also provides a detection method based on the cable resistance detection circuit, which comprises the following steps:

s1: opening the first switch S1, closing the second switch S2, and injecting a sinusoidal voltage with a certain frequency into the cable by using a voltage-controlled oscillator;

s2: detecting the phases of the sinusoidal voltage excitation and the cable response current;

s3: judging whether the phase difference between the sine voltage excitation and the cable response current is 0 or not, if so, executing step S4, if not, converting the phase difference into a voltage quantity, and adjusting the frequency of the sine voltage output by the voltage-controlled oscillator until the phase difference is 0;

s4: locking the frequency of sinusoidal voltage output by the voltage-controlled oscillator, wherein the frequency is the resonant frequency of the cable inductor and the auxiliary capacitor;

s5: and under the frequency, acquiring the resistance value of the cable according to the sinusoidal voltage value and the current value of the cable at the same time.

The invention also provides a method for accurately controlling the far-end voltage based on the detection method, which comprises the following steps of after the resistance value of the cable is obtained:

step S6: opening the second switch S2 and closing the first switch S1 according to v_o(t)＝V_L+i_line(t)R_lineAnd carrying out closed-loop control on the output voltage of the voltage source to realize accurate regulation of the voltage at the tail end of the cable, wherein v_o(t) the voltage, V, of the source end of the cable which needs to be output at the moment t_LDesired input voltage for the load system, R_lineFor the cable voltage value, i, obtained in step S5_line(t) is the current value of the cable at time t.

The further technical scheme of the invention is that after the resistance value of the cable is obtained, the method further comprises the following steps: and step A, disconnecting the second switch S2, closing the first switch S1, dynamically compensating the terminal voltage of the cable according to the loss voltage of the cable, performing closed-loop control on the output voltage of the voltage source, and realizing accurate regulation of the terminal voltage of the cable, wherein the loss voltage of the cable is the product of the current value at the moment t and the voltage value of the cable obtained in the step S5.

To achieve the above object, the present invention further provides a remote power transmission cable terminal voltage control system, including: memory, a processor, and a remote power cable termination voltage control program stored on the memory, the remote power cable termination voltage control program when invoked by the processor performing the steps of the method as described above.

To achieve the above object, the present invention also proposes a computer-readable storage medium storing a remote power transmission cable terminal voltage control program which, when invoked by a processor, performs the steps of the method as described above.

The cable resistance detection circuit, the system and the storage medium for realizing the accurate control of the far-end voltage have the beneficial effects that: according to the invention, the resistance value of the long cable can be obtained at the cable source end by detecting the excitation voltage and the cable response current at the cable source end, so that the remote accurate control on the terminal voltage of the cable can be realized.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a schematic block diagram of a power supply system of the present invention;

FIG. 2 is a schematic diagram of a cable resistance detection circuit of the present invention;

FIG. 3 is a flow chart of a cable resistance detection method according to the present invention.

The objects, features and advantages of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.

In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout includes three juxtapositions, exemplified by "A and/or B" including either A or B or both A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.

The power supply system is shown in a block diagram in figure 1, and the whole system is composed of a voltage source and a cable equivalent total resistance R_lineCable equivalent self-inductance L_lineA load or a secondary power supply, wherein v_oFor the voltage source output voltage (i.e. cable source voltage), v_LFor load terminal voltage or secondary power supply input voltage (i.e. cable end voltage), i_lineFor the current flowing through the cable, C_auxAn auxiliary capacitor needs to be added for detection. The voltage source supplies voltage and current to the load system through the longer cable due to the total resistance R of the cable_lineThe voltage at the tail end of the cable is lower than the actual output voltage of the voltage source in a steady state, so that the voltage at the load end or the input voltage of the secondary power supply is lower than the expected voltage, and the normal work of the system is influenced.

In order to compensate the voltage drop caused by the resistance of a remote cable in the closed-loop control of a voltage source and realize the accurate adjustment of the terminal voltage of the cable, the precondition is that the resistance value of any long cable can be detected. The present invention provides a method for detecting the resistance of a remote cable based on a phase-locked loop.

As shown in fig. 2, the cable resistance detection circuit for implementing precise remote voltage control in this embodiment includes a first switch, a cable resistance detection loop, and an auxiliary capacitor, where the auxiliary capacitor is connected in parallel to the end of a long cable, the first switch and the cable resistance detection loop are both disposed at the source end of the long cable, and the first switch is connected in series to the source end of the long cableThe power output end, cable resistance detection return circuit connects in parallel first switching power supply output end, cable resistance detection return circuit includes voltage detection circuit, current sampling circuit, phase-locked loop and second switch, voltage detection circuit, current sampling circuit are used for gathering the voltage and the electric current of cable source end respectively, and its output links to each other with the phase-locked loop input respectively, phase-locked loop output initial frequency is f_refAnd when the phase difference between the sinusoidal voltage signal injected from the cable source end and the cable response current is 0, the phase-locked loop performs frequency locking on the sinusoidal voltage signal output by the phase-locked loop.

Specifically, the Phase-Locked Loop of this embodiment is an existing feedback control circuit structure, which is referred to as a Phase-Locked Loop (PLL) for short. The phase-locked loop is characterized in that: the frequency and phase of the oscillation signal inside the loop are controlled by an externally input reference signal. Phase-locked loops are commonly used in closed-loop tracking circuits because they allow for automatic tracking of the frequency of the input signal with respect to the frequency of the output signal. In the working process of the phase-locked loop, when the frequency of the output signal is equal to that of the input signal, the phase difference between the output voltage and the input voltage is kept constant, namely the phase of the output voltage and the phase of the input voltage are locked, which is the origin of the name of the phase-locked loop. A Phase-locked Loop generally includes three parts, namely, a Phase Detector (PD), a Loop Filter (LF), and a Voltage Controlled Oscillator (VCO).

In the invention, different from the traditional phase-locked loop control circuit: the sinusoidal voltage excitation output by the voltage-controlled oscillator serves as both the output of the phase-locked loop and the input signal of the phase-locked loop for phase comparison with the cable response current input signal.

The principle of the invention for accurately adjusting the terminal voltage of the cable is as follows:

in the early stage of the voltage source work, S is disconnected₁Closing S₂The initial frequency of the voltage-controlled oscillator is f_refThe sinusoidal voltage signal is injected into the source end of the long cable, the sinusoidal voltage excitation and the cable response current are sampled, and the phase is carried out through the phase discriminatorAnd monitoring, wherein the phase discriminator converts the detected phase difference signal into a voltage signal to be output, the voltage signal is processed by a loop filter to form a control voltage of the voltage-controlled oscillator, so that the frequency of a sinusoidal voltage signal output by the voltage-controlled oscillator is adjusted, and when the phase difference is 0, the phase-locked loop locks the frequency of the sinusoidal voltage signal output by the voltage-controlled oscillator. According to the impedance characteristic, when the phase difference between the sinusoidal voltage excitation signal injected from the source end of the cable and the response current of the cable is 0, the self-inductance L of the cable is indicated_lineAnd an auxiliary capacitor C_auxResonance occurs, i.e. the frequency of the sinusoidal voltage output by the voltage controlled oscillator is at the resonance frequency. At the moment, the input impedance of the cable source end is in a resistance characteristic, sinusoidal voltage and cable response current data under the current frequency are sampled, and the sinusoidal voltage and the cable response current data are obtained according to the characteristicsThe resistance value of the currently used cable can be obtained. Wherein, I_line(t) the current flowing through the cable at time t, V_sineAnd (t) is a sinusoidal voltage value at the time t.

Finally, disconnect S₂Closing S₁According to v_o(t)＝V_L+i_line(t)R_lineAnd carrying out closed-loop control on the output voltage of the voltage source to realize accurate regulation of the voltage at the tail end of the cable, wherein V_LThe desired input voltage for the load system. The voltage at the source end can also be compensated in real time through the voltage drop of the cable, so that the output voltage at the tail end of the cable is a desired value.

As shown in fig. 3, the method for detecting the cable resistance to realize accurate control of the source terminal voltage in this embodiment includes the following specific steps:

step 1: an auxiliary capacitor C is connected in parallel at the tail end of the cable_aux；

Step 2: using a voltage controlled oscillator to output an initial frequency of f_refAnd injecting the sinusoidal voltage signal to the cable source end;

step 3: sampling sine voltage excitation and cable response current, judging the phase difference between the sine voltage excitation and the cable response current, and converting the phase difference into control voltage of a voltage-controlled oscillator;

step 4: judging whether the phase difference is 0, if not, adjusting the frequency of the sinusoidal voltage output by the voltage-controlled oscillator through controlling the voltage until the phase difference is 0, and locking the frequency at the moment, wherein the frequency is the resonant frequency of the cable inductor and the auxiliary capacitor;

step 5: obtaining the resistance value of the cable according to the sinusoidal voltage and the response current value of the cable at the same time under the resonance frequency, namely

The accurate cable resistance detection method based on the phase-locked loop, disclosed by the invention, can obtain the resistance value of the long cable at the cable source end by detecting the excitation voltage and the cable response current of the cable source end, so that the remote accurate control on the terminal voltage of the cable can be realized, and the method has the following beneficial effects:

(1) the resistance value of the cable can be accurately obtained only through an excitation signal, an auxiliary capacitor and a phase-locked loop principle, and the method is simple in logic and easy to implement;

(2) the method solves the problem that the resistance voltage drop of a remote cable causes the undervoltage of a load system, can realize the accurate control of the terminal voltage of the cable, does not need to hang a long cable externally to detect the input voltage of the load system, and has no impact influence on the load system;

(3) the method can realize cable resistance detection only at a single end of the long cable;

(4) the method has no special requirement on the capacitance value of the introduced auxiliary capacitor;

(5) the method can be applied to any power supply system, is not limited by the circuit structure of a load system, and has universality.

In order to achieve the above object, the present invention further provides a system for controlling terminal voltage of a long-distance power transmission cable, the system comprising: the method comprises a memory, a processor and a remote power transmission cable terminal voltage control program stored on the memory, wherein the steps of the method according to the above embodiment are executed when the remote power transmission cable terminal voltage control program is called by the processor, and are not described herein again.

In order to achieve the above object, the present invention further provides a computer-readable storage medium, where a remote power transmission cable end voltage control program is stored, and when the remote power transmission cable end voltage control program is called by a processor, the steps of the method according to the above embodiment are performed, and are not described herein again.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.