Method and device for preventing and controlling adhesion of single-lamp control relay contacts in street lamp lighting system

Abstract

The present invention relates to the field of lighting, and specifically discloses a method and device for preventing contact adhesion of a single-lamp control relay in a street lamp lighting system. The method calculates the relay input moment through the zero-crossing moment of the power supply voltage, calculates the relay cut-off moment through the zero-crossing moment of the power supply voltage and the phase angle difference between the power supply voltage and the load current, and automatically iteratively corrects the switching moment according to the switching effect. The device consists of a voltage signal acquisition module, a voltage signal conditioning module, a load current signal acquisition module, a load current signal conditioning module, an electric energy metering unit, a single-chip microcomputer module, a reset circuit module, an optocoupler module, a control output unit, and a broadband power line carrier communication unit. The present invention can accurately realize on-line protection against contact adhesion during the switching of the single-lamp control relay, is not affected by the load harmonic current, no current is generated in the lamp power supply circuit after disconnection, and the factors such as the aging of the relay itself and the distortion of the performance coefficient do not affect the switching performance.

Description

Technical Field

[0001] The invention belongs to the field of control and protection of street lamp lighting systems, and relates to an on-line protection method and device for single-lamp control relay contact adhesion. Background Art

[0002] In a street lamp lighting system, due to the differences in lamp types and the diversity of the nature of their power factor compensation devices, when a relay is used to control the switching-on and switching-off processes of a single lamp, inrush currents several times higher than the rated current or reverse induced voltages of several thousand volts or more are likely to be generated, and relay contact adhesion often occurs, seriously affecting the system control effect and operation safety.

[0003] Currently known protection methods for single-lamp control relay contact adhesion are the conventional zero-voltage zero-current method and the composite zero-voltage zero-current method. The conventional zero-voltage zero-current method is that after the single-chip microcomputer module receives an input instruction, it acquires the zero-crossing moment of the lamp power supply voltage, and at the subsequent adjacent zero-crossing moment of the voltage, the relay contacts are synchronously closed to reduce the closing inrush current and protect the contacts from adhesion during input; similarly, after the single-chip microcomputer module receives a cut-off instruction, it acquires the zero-crossing moment of the lamp load circuit current, and at the subsequent adjacent zero-crossing moment of the current, the relay contacts are synchronously opened to reduce the reverse induced voltage and reduce the arc ignition energy of the contacts, protecting the contacts from adhesion during cut-off. However, this method is limited by the large amount of harmonics in the lamp current (the lamp is a non-linear load), and its current zero-crossing moment cannot be accurately obtained, so the protection of relay contact adhesion during cut-off cannot be effectively achieved. The composite zero-voltage zero-current method is to use a thyristor and a relay in parallel. When connecting the lamp power supply circuit, the thyristor is turned on first at the zero-crossing moment of the voltage, and then the parallel relay contacts are closed to keep the circuit running normally, and the thyristor exits, realizing the relay's inrush-current-free input; when turning off the lamp power supply circuit, the relay contacts are opened first, and the thyristor is delayed until the current zero-crossing moment and then turned off, realizing the arc-free disconnection of the relay contacts. This method has a high cost, and after the thyristor is turned off, its disconnection resistance is not infinite, and there is still a certain leakage current in the lamp power supply circuit, presenting a safety hazard. Summary of the Invention

[0004] The purpose of the invention is to overcome the above-mentioned disadvantages of the prior art, and without changing the original type of single-lamp control relay, provide an on-line protection method that can effectively avoid single-lamp control relay contact adhesion in a street lamp lighting system, and at the same time provide an on-line protection device for single-lamp control relay contact adhesion in a street lamp lighting system that can be used to implement this method.

[0005] The method for preventing and controlling single-lamp control relay contact adhesion in the street lamp lighting system described in the invention includes the following implementation steps:

[0006] Step 1: The voltage signal acquisition module and the load current signal acquisition module of the on-line protection device for single-lamp control relay contact adhesion are used to collect the instantaneous voltage value u between the power supply L and N and the instantaneous load current value i. The power frequency f of the power supply voltage and the phase angle difference θ between the power supply voltage and the load current are calculated and stored by the electric energy metering unit and the single-chip microcomputer module;

[0007] Step 2: After the relay input command is triggered, the single-chip microcomputer module calculates the input delay time Δt according to formula (1) h and captures the zero-crossing time t of the power supply voltage through the electric energy metering unit u0 , taking the t u0 moment as the starting time reference point, that is, the 0 moment. Starting from the t u0 moment, the single-chip microcomputer module starts timing for Δt h and then issues a relay input command. The relay completes the closing action at the subsequent zero-crossing moment of the voltage,

[0008]

[0009] In formula (1), Δt x,2 is the inherent time of the relay input action, which is determined by the characteristics of the relay itself and is a preset value. m is a positive integer, calculated by rounding [2f*Δt x,2 +1]. t x is the initial generation time of the load current after the single-chip microcomputer module issues the relay input command, measured by the single-chip microcomputer module and the electric energy metering unit, and the initial value is taken as

[0010] Step 3: After the relay cut-off command is triggered, the single-chip microcomputer module calculates the cut-off delay time Δt according to formula (2) d and captures the zero-crossing time t of the voltage through the electric energy metering unit u0 , taking the t u0 moment as the starting time reference point, that is, the 0 moment. Starting from the t u0 moment, the single-chip microcomputer module starts timing for Δt d and then issues a relay cut-off command. The relay completes the disconnection action at the subsequent zero-crossing moment of the current,

[0011]

[0012] In formula (2), Δt y,2 is the inherent time of the relay cut-off action, which is determined by the characteristics of the relay itself and is a preset value. n is a positive integer, calculated by rounding. t y is the moment when the load current finally becomes 0 after the single-chip microcomputer module issues the relay cut-off command, measured by the single-chip microcomputer module and the electric energy metering unit, and the initial value is taken as

[0013] A single-lamp control relay contact adhesion prevention and control device for a street lamp lighting system for implementing the above method, comprising a voltage signal acquisition module, a voltage signal conditioning module, a load current signal acquisition module, a load current signal conditioning module, an electric energy metering unit, a single-chip microcomputer module, a reset circuit module, an opto-coupler module, a control output unit, and a broadband power line carrier communication unit. The output end of the voltage signal acquisition module is electrically connected to the input end of the voltage signal conditioning module; the output end of the load current signal acquisition module is electrically connected to the input end of the load current signal conditioning module; the output ends of the voltage signal conditioning module and the load current signal conditioning module are both electrically connected to the input end of the electric energy metering unit; the output end of the electric energy metering unit and the output end of the reset circuit module are both electrically connected to the input end of the single-chip microcomputer module; the single-chip microcomputer module is electrically connected to the control output unit through the opto-coupler module for completing the on and off actions of the single-lamp control relay; the single-chip microcomputer module is connected to the upper computer through the broadband power line carrier communication unit, and the upper computer can implement functions such as reading and writing, remote monitoring, etc.

[0014] Further, the voltage signal acquisition module is a voltage transformer.

[0015] Further, the voltage signal conditioning module is successively composed of an I / V conversion circuit, an RC filter circuit, an amplification circuit, and a limiting circuit connected in series.

[0016] Further, the load current signal acquisition module is a current transformer.

[0017] Further, the load current signal conditioning module is successively composed of an I / V conversion circuit, an RC filter circuit, an amplification circuit, and a limiting circuit connected in series.

[0018] The present invention has the following beneficial effects:

[0019] First, the method and device of the present invention calculate the relay input time through the zero-crossing moment of the power supply voltage, and calculate the relay cut-off time through the zero-crossing moment of the power supply voltage and the phase angle difference θ between the power supply voltage and the load (lamp) current, instead of directly measuring the zero-crossing moment of the load loop current to calculate the relay cut-off time, avoiding the influence of harmonic current, and the zero-crossing moment of the current can be accurately obtained, and the relay contact cut-off adhesion is effectively protected online;

[0020] Second, for the method and device of the present invention, the relay contact belongs to a dry contact, and no current is generated in the lamp power supply circuit after disconnection, and there is no safety hazard;

[0021] III. The method and device described in the present invention can automatically iteratively correct the switching moment according to the change in the inherent time of the relay's energization and disconnection actions, ensuring the accuracy of the relay's energization at the zero-crossing of voltage and disconnection at the zero-crossing of current, and being unaffected by factors such as the aging of the relay's own lifespan and the distortion of the performance coefficient, effectively providing online protection against the adhesion of the relay's switching contacts. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a schematic structural diagram of the single-lamp control relay contact adhesion prevention and control device for the street lamp lighting system described in the present invention.

[0023] Among them, 1 is the voltage signal acquisition module, 2 is the voltage signal conditioning module, 3 is the load current signal acquisition module, 4 is the load current signal conditioning module, 5 is the electric energy metering unit, 6 is the single-chip microcomputer module, 7 is the reset circuit module, 8 is the optocoupler module, 9 is the control output unit, and 10 is the broadband power line carrier communication unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following will further describe the present invention in detail with reference to the Figure 1 accompanying drawings:

[0025] The basic content of the method for preventing and controlling the adhesion of the single-lamp control relay contacts in the street lamp lighting system described in the present invention is to continuously and synchronously collect the instantaneous value u of the power supply voltage and the instantaneous value i of the load loop current through the voltage signal acquisition module 1 and the load current signal acquisition module 3 of the on-line protection device for the adhesion of the single-lamp control relay contacts in the street lamp lighting system. After being amplified, limited, filtered, and I / V converted by the voltage signal conditioning module 2 and the load current signal conditioning module 4 respectively, they are sent to the electric energy metering unit 5 containing an internal A / D converter. The electric energy metering unit 5 and the single-chip microcomputer module 6 calculate and store the power supply voltage frequency f and the phase angle difference θ between the power supply voltage and the load current.

[0026] The single-chip microcomputer module 6 calculates and stores the initial values of t x and t y When the relay energization command is triggered, the single-chip microcomputer module 6 calculates the relay energization delay time Δt h and captures the zero-crossing moment t of the power supply voltage through the electric energy metering unit 5 u0 . The single-chip microcomputer module 6 of the on-line protection device for the adhesion of the single-lamp control relay contacts in the street lamp lighting system calculates the relay energization delay time Δt according to formula (1) in the method implementation steps in the aforementioned invention content section. h Starting from the moment of t u0 , the time is counted for Δt h, after the timing is completed, the single-chip microcomputer module 6 issues a relay input command, and the relay contact completes the closing action at the moment when the voltage crosses zero. The initial load current generation moment t after the relay is input is measured through the single-chip microcomputer module and the electric energy metering unit x , for the next single-lamp control relay Δt h Correction calculation;

[0027] When the relay cut-off command is triggered, the single-chip microcomputer module 6 calculates the relay cut-off delay time Δt d and captures the moment t when the power supply voltage crosses zero through the electric energy metering unit 5 u0 , and the single-chip microcomputer module 6 of the on-line protection device for the single-lamp control relay contact adhesion of the street lamp lighting system calculates the relay cut-off delay time Δt according to formula (2) in the method implementation steps of the foregoing invention content section d , starting from the moment t u0 to time Δt d , after the timing is completed, the single-chip microcomputer module 6 issues a relay cut-off command, and the relay contact completes the opening action at the moment when the current crosses zero. The final load current after the relay is cut off is measured as 0 moment t through the single-chip microcomputer module and the electric energy metering unit y , for the next single-lamp control relay Δt d Correction calculation.

[0028] The structural embodiment of the on-line protection device for the single-lamp control relay contact adhesion of the street lamp lighting system described in the present invention is as shown in the appendix Figure 1 It includes a voltage signal acquisition module 1, a voltage signal conditioning module 2, a load current signal acquisition module 3, a load current signal conditioning module 4, an electric energy metering unit 5, a single-chip microcomputer module 6, a reset circuit module 7, an opto-coupler module 8, a control output unit 9, and a broadband power line carrier communication unit 10. Among them, the output end of the voltage signal acquisition module 1 is electrically connected to the input end of the voltage signal conditioning module 2; the output end of the load current signal acquisition module 3 is electrically connected to the input end of the load current signal conditioning module 4; the output ends of the voltage signal conditioning module 2 and the load current signal conditioning module 4 are both electrically connected to the input end of the electric energy metering unit 5; the output end of the electric energy metering unit 5 and the output end of the reset circuit module 7 are both electrically connected to the input end of the single-chip microcomputer module 6; the single-chip microcomputer module 6 is electrically connected to the control output unit 9 through the opto-coupler module 8 to complete the closing and opening actions of the single-lamp control relay; the single-chip microcomputer module 6 is connected to the upper computer through the broadband power line carrier communication unit 10, and the upper computer can realize functions such as reading and writing, remote monitoring, etc.

[0029] The voltage signal acquisition module 1 is a voltage transformer.

[0030] The voltage signal conditioning module 2 consists of an I / V conversion circuit, an RC filter circuit, an amplifier circuit, and a limiting circuit that are electrically connected in sequence.

[0031] The load current signal acquisition module 3 is a current transformer.

[0032] The load current signal conditioning module 4 consists of an I / V conversion circuit, an RC filter circuit, an amplifier circuit, and a limiting circuit that are electrically connected in sequence.

[0033] In the structural design of specific examples, the voltage signal acquisition module 1 uses a voltage transformer (such as HPT304A, HRPT-1), the load current signal acquisition module 3 uses a current transformer (such as HCT255A, HRCT-1), and the voltage signal conditioning module 2 and the load current signal conditioning module 4 are implemented by a filter composed of an I / V conversion and amplifier circuit (such as RVC420, LM324 and peripheral auxiliary components), clamping diodes (such as IN4148), limiting zener diodes, and general resistor-capacitor devices. The power metering unit 5 can use devices of the ATT7022 series (such as ATT7022E), the single-chip microcomputer module 6 can use a digital signal processor with built-in multi-channel A / D (such as dsPIC30F6014A), and the opto-coupler module 8 needs to select an opto-coupler device with a larger output driving ability (such as TLP127). The control output unit 9 uses a general control relay (such as JQX-14).

[0034] The working process of the on-line protection for the contact adhesion of the single-lamp control relay in the street lamp lighting system by the device of the present invention is as follows:

[0035] I. The system is powered on, self-checked, and initialized;

[0036] II. Read the preset Δt x,2 、Δt y,2 values;

[0037] III. Check whether there is a fault in the system of the device of the present invention. When there is a fault, transfer to the corresponding processing program and give a fault diagnosis prompt message. When there is no fault, execute the next step;

[0038] IV. Continuously collect the instantaneous voltage value between the power supply L and N of the on-line protection device for the contact adhesion of the single-lamp control relay in the street lamp lighting system and the instantaneous current value of the load circuit;

[0039] V. Calculate and store f and θ of the street lamp lighting system in real time;

[0040] VI. When the relay input command is triggered, the single-chip microcomputer module calculates Δt h and captures t u0 , starts timing Δt u0 from the moment of t h and issues a relay input command, and executes step VII;

[0041] When the relay cut-off instruction is triggered, the single-chip microcomputer module calculates Δt d and captures t u0 , and starts timing Δt from the moment of t u0 . After that, a relay cut-off instruction is issued, and step eight is directly executed; d

[0042] VII. The control output unit closes the single-lamp control relay, and the single-chip microcomputer module and the power metering unit measure t x , which is used to correct Δt of the next single-lamp control relay h , and step nine is executed;

[0043] VIII. The control output unit disconnects the single-lamp control relay, and the single-chip microcomputer module and the power metering unit measure t y , which is used to correct Δt of the next single-lamp control relay d ;

[0044] IX. The broadband power line carrier communication unit uploads the status information of the single-lamp control relay of the street lamp lighting system to the upper computer for remote monitoring;

[0045] X. Repeat step three.

[0046] Through the above description and embodiments, the basic principles, main features and advantages of the present invention are described. In particular, the essence of the present invention is shown - calculating the relay input moment through the zero-crossing moment of the power supply voltage, calculating the relay cut-off moment through the zero-crossing moment of the power supply voltage and the phase angle difference between the power supply voltage and the load current, and automatically iteratively correcting the switching moment according to the switching effect. Without directly measuring the zero-crossing moment of the load loop current, it avoids the interference of the load harmonic current on accurately obtaining the zero-crossing moment of the current, and the switching performance is not affected by factors such as the aging of the relay itself and the distortion of the performance coefficient. It accurately realizes the on-line protection of the contact adhesion during the switching of the single-lamp control relay.

[0047] The actual application methods and application scenarios of the present invention are not limited by the above embodiments. Without departing from the scope of the main idea of the present invention, the present invention will also have various corresponding changes (such as the application scenario changing to other industrial control systems) and improvements. These changes and improvements should fall within the scope of protection required by the present invention, and the scope of protection can be defined by the claims attached to the text of the present invention application and their equivalents.​

Claims

1. The prevention and control method of the single-lamp control relay contact adhesion prevention and control device for the street lamp lighting system, characterized in that It includes the following implementation steps: Step 1: The instantaneous value u of the voltage between the power supply L and N and the instantaneous value i of the load loop current are collected through the voltage signal acquisition module and the load current signal acquisition module. The power supply voltage frequency f and the phase angle difference θ between the power supply voltage and the load current are calculated and stored by the electric energy metering unit and the single-chip microcomputer module; Step 2: After the relay input command is triggered, the single-chip microcomputer module calculates the input delay time Δt according to formula (1). h And the power metering unit is used to capture the zero-crossing moment t of the power supply voltage. u0 , taking the moment t u0 as the starting time reference point, that is, the 0 moment, starting from the moment t u0 to time Δt h later, the single-chip microcomputer module issues a relay input command, and the relay completes the closing action at the subsequent zero-crossing moment of the voltage. In formula (1), Δt x,2 is the inherent time for the relay to operate when energized, which is determined by the characteristics of the relay itself and is a preset value. m is a positive integer, which is obtained by rounding up [2f*Δt x,2 +1], and t x is the initial generation time of the load current after the single-chip microcomputer module issues a relay energization instruction, which is measured by the single-chip microcomputer module and the power metering unit, and the initial value is taken Step 3: After the relay cut-off instruction is triggered, the single-chip microcomputer module calculates the cut-off delay time Δt according to formula (2). d And the power metering unit captures the zero-crossing moment t of the voltage. u0 , taking the moment t u0 as the starting time reference point, that is, the 0 moment, starting from the moment t u0 to time Δt d After that, the single-chip microcomputer module issues a relay cut-off instruction, and the relay completes the disconnection action at the subsequent zero-crossing moment of the current. In formula (2), Δt y,2 is the inherent time for the relay to cut off the action, which is determined by the characteristics of the relay itself and is a preset value. n is a positive integer, which is obtained through rounding calculation. t y is the moment when the load current finally becomes 0 after the single-chip microcomputer module issues a relay cut-off instruction, which is measured by the single-chip microcomputer module and the electric energy metering unit, and the initial value is taken

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