Electric energy meter circuit for extra-high voltage direct current power transmission scene

Abstract

The utility model relates to the technical field of electric energy meters, and provides an electric energy meter circuit for an extra-high voltage direct current power transmission scene, which comprises a pulse modem for converting an analog electric energy signal into a pulse signal and modulating the signal by controlling the width of the pulse, comprising an integrator, a phase compensation unit, a hysteresis comparator and a feedback unit, the multiplier is connected to the pulse modem, realizes product calculation of the voltage and current signals, and comprises a mutual inductor and a switch unit; the filter is connected to the pulse modem and the multiplier, filters high-frequency noise and harmonic waves in the electric energy signal, and comprises a harmonic wave filtering unit and a low-pass filtering unit; and the voltage frequency converter is connected to the pulse modem and the filter and is used for converting the processed analog signal into a frequency signal. Through the technical scheme, the phase shift error is eliminated, and the metering accuracy, the system linearity and the signal quality are improved.

Description

Technical field

[0001] The present application relates to the technical field of electric energy meters, and in particular to an electric energy meter circuit for use in ultra-high voltage direct current (UHVDC) transmission scenarios. [Background Technology]

[0002] In the UHVDC transmission system, the accuracy and stability of gateway metering are crucial for fair transactions in the power market and the management of power grid companies. However, the internal circuits of existing energy meters have the following major shortcomings when facing complex power environments and nonlinear factors: (1) Insufficient accuracy: The internal circuits of existing energy meters are often unable to accurately measure energy consumption when facing high-frequency harmonics and nonlinear factors in the UHVDC transmission system, resulting in large errors in the measurement results. (2) Poor anti-phase shift characteristics: Among the low-pass filter characteristics, the phase shift characteristic has the greatest impact on the linearity of the energy metering system. The existing metering PWM modulation circuit design has insufficient ability to eliminate phase shift (low-pass characteristics), resulting in delayed metering data. (3) Weak anti-interference ability: The electromagnetic interference and high-frequency noise in the UHVDC transmission system are relatively serious. The existing energy metering chip circuit is easily interfered with in a strong electromagnetic environment, affecting the measurement accuracy and stability. The traditional energy metering circuit design lacks effective anti-interference measures and is difficult to ensure measurement accuracy in a complex electromagnetic environment. [Utility Model Content]

[0003] The embodiment of the utility model provides an electric energy meter circuit for ultra-high voltage direct current transmission scenarios, aiming to solve the technical problems existing in the related technologies.

[0004] In a first aspect, an embodiment of the present invention provides an electric energy meter circuit for an ultra-high voltage direct current transmission scenario, comprising: a pulse modem, a multiplier, a filter, and a voltage-frequency converter;

[0005] The pulse modem is used to convert the analog power signal into a pulse signal and realize signal modulation by controlling the width of the pulse, and includes an integrator, a phase compensation unit, a hysteresis comparator and a feedback unit;

[0006] The multiplier is connected to the pulse modem and is used to realize the product calculation of voltage and current signals, and includes a mutual inductor and a switch unit;

[0007] The filter is connected to the pulse modem and the multiplier, and is used to filter out high-frequency noise and harmonics in the power signal, and includes a harmonic filtering unit and a low-pass filtering unit;

[0008] The voltage-to-frequency converter is connected to the pulse modem and the filter, and is used to convert the processed analog signal into a frequency signal.

[0009] In one embodiment, optionally, the integrator includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first comparator, and a first capacitor;

[0010] Among them, the first resistor is connected between the inverting input terminal of the first comparator and the ground, the second resistor is connected between the inverting input terminal and the output terminal of the first comparator, the third resistor is connected between the non-inverting input terminal and the output terminal of the first comparator, the fourth resistor is connected to the output terminal of the first comparator, the fifth resistor is connected between the non-inverting input terminal and the voltage input of the first comparator, the sixth resistor is connected between the non-inverting input terminal of the first comparator and the feedback unit, and the first capacitor is connected between the non-inverting input terminal of the first comparator and the ground.

[0011] In one embodiment, optionally, the phase compensation unit includes a seventh resistor and the fourth resistor, and the seventh resistor is connected between the fourth resistor and the voltage input.

[0012] In one embodiment, optionally, the hysteresis comparator includes the first resistor, the second resistor and a second comparator;

[0013] The inverting input terminal of the second comparator is connected to the fourth resistor, and the output terminal is connected to the feedback unit;

[0014] The feedback unit includes a first switch and a second switch connected in parallel;

[0015] One end of the first switch is connected to a first reference voltage and an output end of the second comparator, and the other end of the first switch is connected to the sixth resistor;

[0016] One end of the second switch is connected to a second reference voltage and the output end of the second comparator, and the other end of the second switch is connected to the sixth resistor;

[0017] The pulse modem further comprises: a voltage dividing unit;

[0018] The voltage dividing unit includes an eighth resistor and a ninth resistor;

[0019] The eighth resistor is connected between the sixth resistor and the non-inverting input terminal of the second comparator;

[0020] The ninth resistor is connected between the non-inverting input terminal of the second comparator and the ground.

[0021] In one embodiment, optionally, the switch unit includes a third switch and a sixth switch connected in parallel, and a fourth switch and a fifth switch connected in parallel, and the switches include MOS transistors.

[0022] In one embodiment, optionally, the low-pass filtering unit is connected between the multiplier and the voltage-frequency converter, and the low-pass filtering unit includes: a first operational amplifier, a tenth resistor, and a second capacitor;

[0023] The tenth resistor and the second capacitor are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the first operational amplifier;

[0024] An inverting input terminal of the first operational amplifier is grounded.

[0025] In one embodiment, optionally, the harmonic filtering unit includes:

[0026] a second operational amplifier, an eleventh resistor, a third capacitor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a fourth capacitor, a fifth capacitor, and a third operational amplifier;

[0027] The eleventh resistor and the third capacitor are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the second operational amplifier;

[0028] The inverting input terminal of the second operational amplifier is grounded;

[0029] The twelfth resistor is connected between the output terminal of the second operational amplifier and the non-inverting input terminal of the first operational amplifier;

[0030] The fourth capacitor and the thirteenth resistor are connected in series between the output terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier;

[0031] The fourteenth resistor is connected across the non-inverting input terminal and the output terminal of the third operational amplifier;

[0032] The fifth capacitor and the fifteenth resistor are connected in series between the output terminal of the third operational amplifier and the non-inverting input terminal of the first operational amplifier;

[0033] An inverting input terminal of the third operational amplifier is grounded.

[0034] In one embodiment, optionally, the voltage-to-frequency converter includes:

[0035] a third comparator, a sixteenth resistor, a transistor, a seventh switch, an eighth switch, a seventeenth resistor, a fourth comparator, a sixth capacitor, a fifth comparator, an eighteenth resistor, a nineteenth resistor, and a tri-state gate;

[0036] The non-inverting input terminal of the third comparator is connected to the reference voltage, the inverting input terminal of the third comparator is connected to the triggered negative voltage Vss through the sixteenth resistor, and the MOS transistor is connected between the inverting input terminal and the output terminal of the third comparator;

[0037] One end of the seventh switch and the eighth switch is connected to the transistor, the other end of the seventh switch is grounded, and the other end of the eighth switch is connected to the non-inverting input of the fourth comparator and the output of the fifth comparator;

[0038] The seventeenth resistor is connected between the non-inverting input terminal of the fourth comparator and the output voltage of the filter, the sixth capacitor is connected across the non-inverting input terminal and the output terminal of the fourth comparator, and the inverting input terminal of the fourth comparator is grounded;

[0039] The output terminal of the fourth comparator is connected to the non-inverting input terminal of the fifth comparator, the eighteenth resistor is connected between the inverting input terminal and the output terminal of the fifth comparator, and the nineteenth resistor is connected between the inverting input terminal of the fifth comparator and ground;

[0040] The tri-state gate is connected between the output terminal of the fifth comparator and the eighth switch.

[0041] In one embodiment, optionally, the method further includes:

[0042] A bias subcircuit has one end connected to a reference voltage and the other end connected to the pulse modem, the multiplier, the filter and the voltage-to-frequency converter.

[0043] In one embodiment, optionally, the MOS transistor includes an HVMOS transistor.

[0044] In the above scheme implemented by the electric energy meter circuit for ultra-high voltage direct current transmission scenarios, the electric energy meter circuit for ultra-high voltage direct current transmission scenarios includes: a pulse modem, a multiplier, a filter, and a voltage-to-frequency converter. The pulse modem is used to convert an analog electric energy signal into a pulse signal and modulate the signal by controlling the pulse width, and includes an integrator, a phase compensation unit, a hysteresis comparator, and a feedback unit. The multiplier, connected to the pulse modem, is used to calculate the product of voltage and current signals and includes a mutual inductor and a switch unit. The filter, connected to the pulse modem and the multiplier, is used to filter out high-frequency noise and harmonics in the electric energy signal and includes a harmonic filter unit and a low-pass filter unit. The voltage-to-frequency converter, connected to the pulse modem and the filter, is used to convert the processed analog signal into a frequency signal. In the present invention, the phase compensation unit is used to compensate for the modem input phase shift, eliminating phase shift errors and improving metering accuracy. The multiplier ensures lossless transmission when the current direction changes through the bidirectional conduction of the mutual inductor current and the switch unit, thereby improving system linearity. The filter adopts harmonic filtering unit and low-pass filtering unit, and uses dual operational amplifiers to clamp the input nodes to ensure that the potentials of the multiplier output nodes are equal, filter out non-target waveforms, and improve signal quality.

Brief Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0046] Figure 1 The following is a schematic diagram showing the structure of an electric energy meter circuit for ultra-high voltage direct current transmission scenarios provided by an embodiment of the present utility model;

[0047] Figure 2 A schematic diagram of the structure of an integrator in an electric energy meter circuit for ultra-high voltage direct current transmission scenarios provided by an embodiment of the present utility model is shown;

[0048] Figure 3 A schematic diagram of the structure of a multiplier in an electric energy meter circuit for ultra-high voltage direct current transmission scenarios provided by an embodiment of the present utility model is shown;

[0049] Figure 4 A schematic diagram showing the association of multiplier MOS tubes in an electric energy meter circuit for ultra-high voltage direct current transmission scenarios provided by an embodiment of the present invention is shown;

[0050] Figure 5A schematic diagram of the structure of a filter in an electric energy meter circuit for ultra-high voltage direct current transmission scenarios provided by an embodiment of the present utility model is shown;

[0051] Figure 6 A schematic structural diagram of a voltage-frequency converter in an electric energy meter circuit for ultra-high voltage direct current (UHVDC) transmission scenarios provided by an embodiment of the present invention is shown. [Specific implementation method]

[0052] In order to better understand the technical solution of the present invention, the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0053] It should be understood that the embodiments described are only a portion of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0054] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates otherwise.

[0055] In order to solve the technical problems of poor accuracy and poor stability of existing electric energy meters when encountering nonlinear and noise factors, the utility model proposes an electric energy meter circuit for ultra-high voltage direct current transmission scenarios.

[0056] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0057] See also Figure 1 , Figure 1 The figure shows a schematic structural diagram of an electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to an embodiment of the present invention.

[0058] like Figure 1 As shown, according to one embodiment of the present invention, an electric energy meter circuit for ultra-high voltage direct current transmission scenarios includes:

[0059] Pulse modem 11, multiplier 12, filter 13 and voltage-to-frequency converter 14;

[0060] The pulse modem 11 is used to convert the analog power signal into a pulse signal and modulate the signal by controlling the width of the pulse, and includes an integrator, a phase compensation unit, a hysteresis comparator and a feedback unit;

[0061] The multiplier 12 is connected to the pulse modem 11 and is used to calculate the product of the voltage and current signals, and includes a mutual inductor and a switch unit;

[0062] The filter 13 is connected to the pulse modem 11 and the multiplier 12 and is used to filter out high-frequency noise and harmonics in the power signal, and includes a harmonic filtering unit and a low-pass filtering unit;

[0063] The voltage-to-frequency converter 14 is connected to the pulse modem 11 and the filter 13 , and is configured to convert the processed analog signal into a frequency signal.

[0064] In one embodiment, optionally, the method further includes:

[0065] The bias sub-circuit 15 has one end connected to the reference voltage and the other end connected to the pulse modem 11 , the multiplier 12 , the filter 13 and the voltage-to-frequency converter 14 .

[0066] This utility model provides a new circuit structure design for electric energy meter, which is used to solve the technical problems of poor accuracy and stability of existing electric energy meter when encountering nonlinear and noise factors. The circuit design mainly includes four parts: pulse width modulator, multiplier, filter and voltage frequency converter. The main circuit of the electric energy meter is as follows: Figure 1 As shown in the figure, the phase compensation unit compensates for the modem input phase shift, eliminating phase shift errors and improving measurement accuracy. The multiplier uses bidirectional current conduction through the transformer, along with a switch unit, to ensure lossless transmission when current direction changes, improving system linearity. The filter utilizes a harmonic filter unit and a low-pass filter unit, using dual op amps to clamp the input nodes, ensuring equal potential at the multiplier output nodes, filtering out non-target waveforms, and improving signal quality.

[0067] like Figure 2 As shown, in one embodiment, optionally, the integrator includes: a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a first comparator A1 and a first capacitor C1;

[0068] The first resistor R1 is connected between the inverting input terminal of the first comparator A1 and ground, the second resistor R2 is connected between the inverting input terminal and the output terminal of the first comparator A1, the third resistor R3 is connected between the non-inverting input terminal and the output terminal of the first comparator A1, the fourth resistor R4 is connected to the output terminal of the first comparator A1, the fifth resistor R5 is connected between the non-inverting input terminal and the voltage input of the first comparator A1, the sixth resistor R6 is connected between the non-inverting input terminal of the first comparator A1 and the feedback unit, and the first capacitor C1 is connected between the non-inverting input terminal of the first comparator A1 and ground.

[0069] In one embodiment, optionally, the phase compensation unit includes a seventh resistor R7 and the fourth resistor R4 , and the seventh resistor R7 is connected between the fourth resistor R4 and the voltage input Vin.

[0070] In one embodiment, optionally, the hysteresis comparator includes the first resistor R1, the second resistor R2, and a second comparator Comp1;

[0071] The inverting input terminal of the second comparator Comp1 is connected to the fourth resistor R4, and the output terminal is connected to the feedback unit;

[0072] The feedback unit includes a first switch S1 and a second switch S2 connected in parallel;

[0073] One end of the first switch S1 is connected to the first reference voltage VrefL and the output end of the second comparator Comp1, and the other end of the first switch S1 is connected to the sixth resistor R6;

[0074] One end of the second switch S2 is connected to the second reference voltage VrefH and the output end of the second comparator Comp1, and the other end of the second switch S2 is connected to the sixth resistor R6;

[0075] The pulse modem further comprises: a voltage dividing unit;

[0076] The voltage dividing unit includes an eighth resistor R8 and a ninth resistor R9;

[0077] The eighth resistor R8 is connected between the sixth resistor R6 and the non-inverting input terminal of the second comparator Comp1;

[0078] The ninth resistor R9 is connected between the non-inverting input terminal of the second comparator Comp1 and the ground.

[0079] In this embodiment, the integrator connects the capacitor to V pWhen the op amp is in its linear region, the voltage across R6 is zero, and R1 = R2, the voltage across the capacitor drops to 50% of the output voltage, minimizing voltage-induced capacitor nonlinearity errors. For a hysteresis comparator, as the input voltage Vin(t) gradually rises, once the input voltage exceeds the threshold, the output of Comp1 switches to a high level. At this point, positive feedback applies the feedback voltage to the negative input of the first comparator A1 through R1 and R2, further increasing the voltage at the input and ensuring that the output of Comp1 remains high, preventing false triggering caused by slight fluctuations in the input signal. When the input voltage drops below the lower threshold, the output of Comp1 switches to a low level. The feedback unit applies a negative feedback voltage to the input through R1 and R2, reducing the input voltage and ensuring that the output of Comp1 remains low, preventing output switching caused by slight fluctuations in the input signal.

[0080] R8 and R9 form a voltage divider network that sets the reference voltage at the input of the first comparator, A1. This means that the voltage at the negative input (i.e., the inverting input) of the first comparator, A1, is determined by R8 and R9, and this voltage determines the conditions under which the first comparator triggers its output. By adjusting the resistance values ​​of R8 and R9, the trigger voltage threshold of the first comparator can be changed. The first comparator typically compares the input voltage with this threshold to generate a pulse-width modulated (PWM) signal.

[0081] The threshold voltage of the hysteresis comparator circuit can be expressed as:

[0082]

[0083] Among them, V FB V refL and V refH The absolute value of the formula is determined by the output of the first comparator. The pulse width modulator circuit does not directly use the output of the first comparator because there is typically a relatively large absolute difference between the positive and negative potentials of the first comparator's output. When the feedback signal is also transmitted to the integrator, this difference can cause large errors in the modulator, which in turn degrades the performance of the PWM module. Therefore, the output of the first comparator requires a high-precision off-chip voltage signal as the feedback voltage. Reducing the resistance of R9 in the circuit also reduces the threshold of the first comparator, narrowing the voltage range of the integrator's output and improving the linearity of the resistor and capacitor. However, this results in a higher frequency signal at the integrator's output.

[0084] In the above-described embodiment, the integrator, phase compensation unit, hysteresis comparator, and feedback unit are used to compensate for the pulse width modulator input phase shift, eliminating phase shift errors. Compared to conventional energy meters, the present invention can more accurately reflect actual energy consumption, significantly improving metering accuracy. Increasing the modulation frequency of the pulse width modulator effectively suppresses the impact of quantization noise on metering accuracy. Compared to existing technologies, the present invention can provide higher metering accuracy in environments with high-frequency harmonics and nonlinear loads.

[0085] like Figure 3 As shown, in one embodiment, optionally, the multiplier includes a mutual inductor L and a switch unit, the switch unit includes a third switch S3 and a sixth switch S6 connected in parallel, and a fourth switch S4 and a fifth switch S5 connected in parallel, and the switches include MOS tubes.

[0086] In one embodiment, optionally, the MOS transistor includes an HVMOS transistor.

[0087] from Figure 3 It can be seen that S3 and S6 are connected in parallel, and S4 and 56 are connected in parallel. The specific parallel connection method is as follows Figure 4 shown.

[0088] In the multiplier circuit, the switch in the multiplier needs to conduct the current converted by the transformer. The transformer here can be regarded as a current source, and the current source is sinusoidal, and the direction of the current will reverse after half a cycle. Therefore, the switch should be implemented by connecting two MOS tubes in parallel to cope with the change in current flow direction. When ν PWM When the value of (t) remains unchanged, the transformer on the left of the circuit is directly connected to the output on the right through the switch's on-resistance. Because there's only one branch, the current in the transformer is transmitted to the output without loss. In the multiplier implementation, to ensure voltage resistance, MOS transistors with relatively large gate areas, typically produced in a voltage-resistant process, are selected. For high input currents, such as milliampere levels, this reduces the switch's on-resistance and improves the linearity of the metering system.

[0089] In this embodiment, two MOS transistors are connected in parallel in the multiplier and a high-voltage MOS transistor is used to reduce on-resistance, achieve bidirectional conduction of the transformer current, ensure lossless transmission when the current direction changes, and improve system linearity.

[0090] like Figure 5 As shown, in one embodiment, optionally, the filter 13 includes a harmonic filtering unit and a low-pass filtering unit. The low-pass filtering unit is connected between the multiplier and the voltage-frequency converter, and the low-pass filtering unit includes: a first operational amplifier A3, a tenth resistor R10 and a second capacitor C2;

[0091] The tenth resistor R10 and the second capacitor C2 are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the first operational amplifier A3;

[0092] An inverting input terminal of the first operational amplifier A3 is grounded.

[0093] In one embodiment, optionally, the harmonic filtering unit includes:

[0094] a second operational amplifier A4, an eleventh resistor R11, a third capacitor C3, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, a fourth capacitor C4, a fifth capacitor C5, and a third operational amplifier A5;

[0095] The eleventh resistor R11 and the third capacitor C3 are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the second operational amplifier A4;

[0096] The inverting input terminal of the second operational amplifier A4 is grounded;

[0097] The twelfth resistor R12 is connected between the output terminal of the second operational amplifier A4 and the non-inverting input terminal of the first operational amplifier A3;

[0098] The fourth capacitor C4 and the thirteenth resistor R13 are connected in series between the output terminal of the second operational amplifier A4 and the non-inverting input terminal of the third operational amplifier A5;

[0099] The fourteenth resistor R14 is connected between the non-inverting input terminal and the output terminal of the third operational amplifier A5;

[0100] The fifth capacitor C5 and the fifteenth resistor R15 are connected in series between the output terminal of the third operational amplifier A5 and the non-inverting input terminal of the first operational amplifier A3;

[0101] An inverting input terminal of the third operational amplifier A5 is grounded.

[0102] In this embodiment, A4 and A5 and their surrounding capacitors and resistors implement harmonic filtering, and A3 and its surrounding capacitors and resistors implement low-pass filtering. Among them, the harmonic filtering unit inputs the current or voltage (including unwanted harmonics) output by the multiplier, and outputs: a current or voltage signal with unwanted components (harmonics) filtered out. Specifically, the configuration of the operational amplifier A3 and the capacitors and resistors around it form an active low-pass filter. By selecting appropriate resistance and capacitance values, the cutoff frequency of the filter can be set. The cutoff frequency is usually determined by the time constant in the filter circuit, such as f c= 1 / 2πRC, where R is the resistor and C is the capacitor. Signals above the cutoff frequency are gradually attenuated, while signals below the cutoff frequency are passed. The capacitors in the circuit may act as energy storage elements, allowing low-frequency signals to gradually pass while short-circuiting or attenuating rapidly changing high-frequency signals, thereby achieving a low-pass filtering effect. The operational amplifiers A4 and A5, along with their associated capacitors and resistors, combine to form an active harmonic filter that specifically suppresses specific harmonics. Through positive or negative feedback, it can produce a bandpass or bandstop filtering effect, attenuating harmonic components of specific frequencies. For example, if a specific frequency harmonic needs to be filtered out (such as the 150Hz third harmonic of a 50Hz power supply harmonic), the filter parameters can be adjusted to maximize attenuation of that harmonic while preserving other frequency components.

[0103] In the above embodiment, the filter includes harmonic filtering and low-pass filtering. Dual op amps are used to clamp the input nodes, ensuring equal potential at the multiplier output nodes, filtering out non-target waveforms and improving signal quality. The use of high open-loop gain op amps significantly reduces nonlinear errors in the metering circuit. Compared to traditional energy meters, the optimized op amp design results in more accurate metering results, especially in complex load environments.

[0104] like Figure 6 As shown, in one embodiment, optionally, the voltage-to-frequency converter includes:

[0105] a third comparator A6, a sixteenth resistor R16, a transistor M1, a seventh switch S7, an eighth switch S8, a seventeenth resistor R17, a fourth comparator A7, a sixth capacitor C6, a fifth comparator A8, an eighteenth resistor R18, a nineteenth resistor R19, and a tri-state gate Tri;

[0106] The non-inverting input terminal of the third comparator A6 is connected to the reference voltage, the inverting input terminal of the third comparator A6 is connected to the triggered negative voltage Vss through the sixteenth resistor R16, and the MOS transistor M1 is connected between the inverting input terminal and the output terminal of the third comparator A6;

[0107] One end of the seventh switch S7 and the eighth switch S8 is connected to the transistor M1, the other end of the seventh switch S7 is grounded, and the other end of the eighth switch S8 is connected to the non-inverting input end of the fourth comparator A7 and the output end of the fifth comparator A8;

[0108] The seventeenth resistor R17 is connected between the non-inverting input terminal of the fourth comparator A7 and the output voltage Vin of the filter, the sixth capacitor C6 is connected between the non-inverting input terminal and the output terminal of the fourth comparator A7, and the inverting input terminal of the fourth comparator A7 is grounded;

[0109] The output terminal of the fourth comparator A7 is connected to the non-inverting input terminal of the fifth comparator A8, the eighteenth resistor R18 is connected between the inverting input terminal and the output terminal of the fifth comparator A8, and the nineteenth resistor R19 is connected between the inverting input terminal of the fifth comparator A8 and ground;

[0110] The tri-state gate Tri is connected between the output terminal of the fifth comparator A8 and the eighth switch S8.

[0111] In this embodiment, the voltage and current signals input by the voltage-to-frequency converter are first converted into a voltage signal representing power through a time-division multiplier. This voltage signal is then converted into a pulse signal with a duty cycle representing the power level through a voltage-to-frequency converter (VFC). After the pulse signal is converted into the number of pulses of a high-frequency clock, this number of pulses becomes the power signal corresponding to the input voltage and current.

[0112] The voltage-to-frequency converter circuit uses a structure similar to that of a hysteresis comparator, but the feedback signal is converted into a current signal. Therefore, the feedback voltage of the hysteresis comparator directly uses the output voltage of the comparator.

[0113] like Figure 6 As shown in Figure 1, the negative feedback of the loop is generated by an integrator rather than a comparator. The feedback current is implemented using a simple LDO structure that can generate a current that is equal to V ref Fixed current with similar accuracy.

[0114] The S7 and S8 switches primarily control the connection of the LDO. When the LDO is connected to the input branch via S7, the op amp's clamping characteristics clamp the LDO's output node at zero potential. If S8 is absent and disconnected, the drain of M1 in the LDO will be pulled to Vss. When S7 is closed again, the drain of M1 requires time to return to zero potential before it can output the normal reference current. Therefore, to reduce the LDO's settling time, its output node should also be fixed at zero potential when the LDO is disconnected from the input branch. Therefore, the other end of S8 should be connected to zero potential.

[0115] In addition to controlling the feedback voltage, the output of the fifth comparator also has the core function of controlling the tri-state gate to modulate the input clock signal. The function of the tri-state gate is that when the control terminal is high, the output signal is equal to the input; when the control terminal is low, the output signal remains in a high-impedance state. Therefore, within a certain period of time, when the input signal remains constant, the duty cycle of the tri-state gate remains unchanged, so the number of output pulses also remains unchanged. Since the output v DTo control the output of a high-frequency clock signal and maintain the signal-to-noise ratio of the output pulse signal, the modulator's output frequency should be relatively low, but not so low that the meter's pulse constant becomes too small, which would require more pulses to be accumulated. Therefore, compared to the integrator capacitance in PWM, the capacitance in this structure is larger, resulting in less modulator nonlinearity and suppressing and attenuating the high-frequency quantization noise in the output, thereby improving system accuracy.

[0116] In the above embodiment, the voltage-to-frequency converter employs a structure similar to a hysteresis comparator. The feedback signal is converted into a current signal, which is then fed back through an integrator to generate negative feedback, improving system stability. A tri-state gate controls the modulation of the input clock signal, ensuring the signal-to-noise ratio of the output pulse signal. The modulator output frequency is relatively low, improving system accuracy.

[0117] It is understandable that the selection of each component and the signal type of the voltage signal can be selected and set according to the actual scenario of production design, and this embodiment does not make specific limitations.

[0118] It should be noted that the circuit functions of the energy meter for UHVDC transmission scenarios provided in this embodiment are primarily implemented through the circuit connections between various circuit modules, and do not rely on the implementation of program modules within a particular circuit module. Furthermore, the various circuit modules in the energy meter circuit for UHVDC transmission scenarios can be implemented using either analog or digital circuits, and for circuit modules that can be embedded with program modules, their module functions can be implemented using program modules provided by conventional technologies.

[0119] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0120] It should be understood that although the terms "first," "second," etc. may be used to describe the setting units in the embodiments of the present invention, these setting units should not be limited to these terms. These terms are merely used to distinguish the setting units from each other. For example, without departing from the scope of the embodiments of the present invention, the first setting unit may also be referred to as the second setting unit, and similarly, the second setting unit may also be referred to as the first setting unit.

[0121] The word "if," as used herein, may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0122] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative. For example, the division of the units is merely a logical function 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. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection of the system or unit, which may be electrical, mechanical or other forms.

[0123] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0124] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. An electric energy meter circuit for ultra-high voltage direct current transmission scenarios, characterized in that: include: pulse modems, multipliers, filters, and voltage-to-frequency converters; The pulse modem is used to convert the analog power signal into a pulse signal and realize signal modulation by controlling the width of the pulse, and includes an integrator, a phase compensation unit, a hysteresis comparator and a feedback unit; The multiplier is connected to the pulse modem and is used to realize the product calculation of voltage and current signals, and includes a mutual inductor and a switch unit; The filter is connected to the pulse modem and the multiplier, and is used to filter out high-frequency noise and harmonics in the power signal, and includes a harmonic filtering unit and a low-pass filtering unit; The voltage-to-frequency converter is connected to the pulse modem and the filter, and is used to convert the processed analog signal into a frequency signal.

2. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 1, characterized in that: The integrator includes: a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a first comparator and a first capacitor; Among them, the first resistor is connected between the inverting input terminal of the first comparator and the ground, the second resistor is connected between the inverting input terminal and the output terminal of the first comparator, the third resistor is connected between the non-inverting input terminal and the output terminal of the first comparator, the fourth resistor is connected to the output terminal of the first comparator, the fifth resistor is connected between the non-inverting input terminal and the voltage input of the first comparator, the sixth resistor is connected between the non-inverting input terminal of the first comparator and the feedback unit, and the first capacitor is connected between the non-inverting input terminal of the first comparator and the ground.

3. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 2, characterized in that: The phase compensation unit includes a seventh resistor and the fourth resistor, and the seventh resistor is connected between the fourth resistor and the voltage input.

4. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 2, characterized in that: The hysteresis comparator includes the first resistor, the second resistor and a second comparator; The inverting input terminal of the second comparator is connected to the fourth resistor, and the output terminal is connected to the feedback unit; The feedback unit includes a first switch and a second switch connected in parallel; One end of the first switch is connected to a first reference voltage and an output end of the second comparator, and the other end of the first switch is connected to the sixth resistor; One end of the second switch is connected to a second reference voltage and the output end of the second comparator, and the other end of the second switch is connected to the sixth resistor; The pulse modem further comprises: a voltage dividing unit; The voltage dividing unit includes an eighth resistor and a ninth resistor; The eighth resistor is connected between the sixth resistor and the non-inverting input terminal of the second comparator; The ninth resistor is connected between the non-inverting input terminal of the second comparator and the ground.

5. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 1, characterized in that: The switch unit includes a third switch and a sixth switch connected in parallel, and a fourth switch and a fifth switch connected in parallel, and the switches include MOS tubes.

6. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 1, characterized in that: The low-pass filtering unit is connected between the multiplier and the voltage-frequency converter, and the low-pass filtering unit includes: a first operational amplifier, a tenth resistor, and a second capacitor; The tenth resistor and the second capacitor are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the first operational amplifier; An inverting input terminal of the first operational amplifier is grounded.

7. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 6, characterized in that: The harmonic filtering unit includes: a second operational amplifier, an eleventh resistor, a third capacitor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a fourth capacitor, a fifth capacitor, and a third operational amplifier; The eleventh resistor and the third capacitor are connected in parallel and bridged between the non-inverting input terminal and the output terminal of the second operational amplifier; The inverting input terminal of the second operational amplifier is grounded; The twelfth resistor is connected between the output terminal of the second operational amplifier and the non-inverting input terminal of the first operational amplifier; The fourth capacitor and the thirteenth resistor are connected in series between the output terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier; The fourteenth resistor is connected across the non-inverting input terminal and the output terminal of the third operational amplifier; The fifth capacitor and the fifteenth resistor are connected in series between the output terminal of the third operational amplifier and the non-inverting input terminal of the first operational amplifier; An inverting input terminal of the third operational amplifier is grounded.

8. The electric energy meter circuit for ultra-high voltage direct current transmission according to claim 5, characterized in that: The voltage-to-frequency converter includes: a third comparator, a sixteenth resistor, a transistor, a seventh switch, an eighth switch, a seventeenth resistor, a fourth comparator, a sixth capacitor, a fifth comparator, an eighteenth resistor, a nineteenth resistor, and a tri-state gate; The non-inverting input terminal of the third comparator is connected to the reference voltage, the inverting input terminal of the third comparator is connected to the triggered negative voltage Vss through the sixteenth resistor, and the MOS transistor is connected between the inverting input terminal and the output terminal of the third comparator; One end of the seventh switch and the eighth switch is connected to the transistor, the other end of the seventh switch is grounded, and the other end of the eighth switch is connected to the non-inverting input of the fourth comparator and the output of the fifth comparator; The seventeenth resistor is connected between the non-inverting input terminal of the fourth comparator and the output voltage of the filter, the sixth capacitor is connected across the non-inverting input terminal and the output terminal of the fourth comparator, and the inverting input terminal of the fourth comparator is grounded; The output terminal of the fourth comparator is connected to the non-inverting input terminal of the fifth comparator, the eighteenth resistor is connected between the inverting input terminal and the output terminal of the fifth comparator, and the nineteenth resistor is connected between the inverting input terminal of the fifth comparator and ground; The tri-state gate is connected between the output terminal of the fifth comparator and the eighth switch.

9. The electric energy meter circuit for ultra-high voltage direct current transmission scenarios according to claim 1, characterized in that: Also includes: A bias subcircuit has one end connected to a reference voltage and the other end connected to the pulse modem, the multiplier, the filter and the voltage-to-frequency converter.

10. The electric energy meter circuit for ultra-high voltage direct current transmission according to claim 5, characterized in that: The MOS transistor includes an HVMOS transistor.

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