CN210347815U - Photovoltaic harmonic monitoring device based on electric energy metering chip - Google Patents
Photovoltaic harmonic monitoring device based on electric energy metering chip Download PDFInfo
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- CN210347815U CN210347815U CN201921066196.9U CN201921066196U CN210347815U CN 210347815 U CN210347815 U CN 210347815U CN 201921066196 U CN201921066196 U CN 201921066196U CN 210347815 U CN210347815 U CN 210347815U
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Abstract
The utility model discloses a photovoltaic harmonic monitoring device based on an electric energy metering chip, which comprises a signal input unit used for converting an original voltage signal and an original current signal obtained from a power grid monitoring point into a low voltage signal and a low current signal respectively; the signal conditioning circuit acquires a low-voltage signal and a low-current signal through the signal input unit, and can respectively convert the bipolar low-voltage signal and the bipolar low-current signal into unidirectional sinusoidal signals to be output to the electric energy metering chip; the electric energy metering chip can convert the unidirectional sinusoidal signal into a digital signal, calculate the electric quantity parameter of the photovoltaic power grid, and output the electric quantity parameter to a microprocessor capable of calculating total harmonic distortion according to the electric quantity parameter of the photovoltaic power grid. The utility model provides an among the prior art technical problem that circuit module is more, circuit structure is complicated.
Description
Technical Field
The utility model relates to a photovoltaic power quality testing technical field especially relates to a device for monitoring photovoltaic harmonic.
Background
With the increasingly severe global energy situation and the continuous development of new energy, more and more photovoltaic power generation is gradually put into a power grid, and meanwhile, with the continuous improvement of the installed capacity of the photovoltaic power generation, higher technical performance requirements are provided for the safety, economy, quality, reliability and the like of system power supply after the photovoltaic power generation is connected to the grid. The photovoltaic power source is a harmonic source, and the start-stop frequency of the photovoltaic power source is increased due to the access of a nonlinear load and the change of the load, so that a series of power quality problems are caused. The harmonic waves are key factors influencing the electric energy quality of the photovoltaic system and are main reasons influencing the safe, stable, energy-saving and economic operation of the photovoltaic power generation system and even the whole power system.
Compared with other electric energy qualities, the detection result of the harmonic wave of the photovoltaic system can reflect electric energy quality parameters such as harmonic wave distortion and power factors of the photovoltaic inverter in time, the photovoltaic system can be controlled, managed and predicted in time, and latent and sudden severe accidents can be prevented. At present, no matter scientific research institutions, colleges and universities, manufacturers or operation, maintenance and management departments in an electric power system are concerned about the development of the harmonic monitoring technology of the photovoltaic system.
At present, although some devices for monitoring photovoltaic harmonics also exist, a plurality of circuit modules including an analog-to-digital conversion sampling module and a plurality of electrical parameter sampling modules are required, so that the circuit structure is complex, and the monitoring device is large in size.
SUMMERY OF THE UTILITY MODEL
Not enough to above-mentioned prior art, the utility model provides a photovoltaic harmonic monitoring devices based on electric energy measurement chip solves the technical problem that circuit module is more, circuit structure is complicated among the prior art.
In order to solve the technical problem, the utility model discloses a following technical scheme: a photovoltaic harmonic monitoring device based on an electric energy metering chip comprises a signal input unit, a signal output unit and a signal output unit, wherein the signal input unit is used for converting an original voltage signal and an original current signal obtained from a power grid monitoring point into a low voltage signal and a low current signal respectively; the signal conditioning circuit acquires a low-voltage signal and a low-current signal through the signal input unit, and can respectively convert the bipolar low-voltage signal and the bipolar low-current signal into unidirectional sinusoidal signals to be output to the electric energy metering chip; the electric energy metering chip can convert the unidirectional sinusoidal signal into a digital signal, calculate the electric quantity parameter of the photovoltaic power grid, and output the electric quantity parameter to a microprocessor capable of calculating total harmonic distortion according to the electric quantity parameter of the photovoltaic power grid.
Further, the signal input unit comprises 4 groups of voltage transformers and 4 groups of current transformers; the 4 groups of voltage transformers are used for converting three-phase voltage and zero-sequence voltage of a power grid monitoring point into 4-path low-voltage signals respectively; and the 4 groups of current transformers are used for converting the three-phase current and the zero-sequence current of the power grid monitoring point into 4 paths of low-current signals respectively.
Further, the signal conditioning circuit comprises an operational amplifier; the inverting input end of the operational amplifier is connected with the ground through a resistor R1, and the inverting input end is connected with the output end through a resistor R2; the non-inverting input terminal of the operational amplifier receives the bipolar input signal through a resistor R3, and a reference voltage is connected between the resistor R3 and the non-inverting input terminal through a resistor R4.
Further, the model of the electric energy metering chip is CSE 7780.
Further, the microprocessor is an ARM microprocessor with the model number of LPC 2136.
Compared with the prior art, the utility model discloses following beneficial effect has:
1. in the prior art, various electrical quantity parameters (analog signals) of a photovoltaic power grid are respectively collected by adopting various electrical quantity parameter sampling modules, and then the analog signals are converted into digital signals by an analog-to-digital conversion module and output to a processor for processing. However, the utility model discloses owing to adopted the electric energy measurement chip, the integration of electric energy measurement chip itself has the modulus conversion module to the electric quantity parameter is calculated according to electric current and voltage to the basic function of electric energy measurement chip, thereby will gather the problem of various electric quantity parameters through various electric quantity parameter sampling module, the problem of conversion for acquisition current and voltage makes circuit structure simplify.
2. In order to meet the input requirements of the signal conditioning circuit, the signal input unit converts an original signal obtained from a power grid monitoring point into a low-voltage signal and a low-current signal. Because the low-voltage signal and the low-current signal are bipolar signals (sinusoidal signals with positive half cycles and negative half cycles), the signal conditioning circuit is adopted to convert the bipolar signals into unidirectional sinusoidal signals suitable for the electric energy metering chip to process.
3. Finished products can be purchased from the market by the microprocessor capable of calculating the total harmonic distortion according to the electric quantity parameters of the photovoltaic power grid, and the research and development cost can be greatly reduced.
Drawings
FIG. 1 is a block circuit diagram of a photovoltaic harmonic monitoring device based on an electric energy metering chip in the present embodiment;
FIG. 2 is a circuit schematic of a signal conditioning circuit;
fig. 3 is a logical composition structural diagram of an electric energy metering chip of the CSE 7780.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and preferred embodiments.
Referring to fig. 1, a photovoltaic harmonic monitoring device based on an electric energy metering chip includes a signal input unit 11 for converting an original voltage signal and an original current signal obtained from a power grid monitoring point into a low voltage signal and a low current signal, respectively; the signal conditioning circuit 12 acquires a low voltage signal and a low current signal through a signal input unit, and can respectively convert the bipolar low voltage signal and the bipolar low current signal into unidirectional sinusoidal signals to be output to the electric energy metering chip 13, wherein the model of the electric energy metering chip 13 is CSE 7780; the electric energy metering chip 13 can convert the unidirectional sinusoidal signal into a digital signal, calculate the electrical quantity parameters (including active power and power factor) of the photovoltaic power grid, and output the electrical quantity parameters to the microprocessor 14 which can calculate the total harmonic distortion according to the electrical quantity parameters of the photovoltaic power grid; the microprocessor 14 is an ARM microprocessor with the model number LPC 2136. The microprocessor 14 is loaded with a harmonic detection program (the harmonic detection program is an existing program), and can analyze the voltage and the current acquired in real time on line, calculate the power factor and the total harmonic distortion of the photovoltaic power grid in time and provide harmonic information.
In this specific embodiment, the signal input unit includes 4 sets of voltage transformers and 4 sets of current transformers; the 4 groups of voltage transformers are used for converting three-phase voltage and zero-sequence voltage of a power grid monitoring point into 4-path low-voltage signals respectively; and the 4 groups of current transformers are used for converting the three-phase current and the zero-sequence current of the power grid monitoring point into 4 paths of low-current signals respectively.
Referring to fig. 2, in this embodiment, the signal conditioning circuit includes an operational amplifier; the inverting input end of the operational amplifier is connected with the ground through a resistor R1, and the inverting input end is connected with the output end through a resistor R2; the non-inverting input terminal of the operational amplifier receives the bipolar input signal through a resistor R3, and a reference voltage is connected between the resistor R3 and the non-inverting input terminal through a resistor R4. The signal conditioning circuit can convert the bipolar signal into a required signal, can realize isolated transmission of an input signal, and effectively reduces interference.
The principle of the signal conditioning circuit is as follows: converting a bipolar signal (for example, -5V to + 5V) into a unidirectional sinusoidal signal (for example, 0 to 5V), wherein the sinusoidal signal: RN = RP, RN = R1/R3, RP = R4/R2. RN is the equivalent resistance of two input end external paths, and RP is the balanced resistance, and its effect is: providing a proper static bias for the transistor inside the chip; eliminating influence of quiescent base current on output voltage, the magnitude of which is in accordance with external path of two input terminalsEquivalent resistanceThe values are balanced.
The utility model discloses owing to adopted the electric energy measurement chip, the electric energy measurement chip itself is integrated to have the modulus conversion module to the basic function of electric energy measurement chip is according to electric current and power calculation electric quantity parameter, thereby will gather the problem of various electric quantity parameters through various electric quantity parameter sampling module, and the conversion is for the problem of acquisition current and voltage, makes circuit structure can simplify: the utility model discloses a signal acquisition unit's that signal conditioning circuit and electric energy measurement chip combination formed function is equivalent to the signal acquisition unit's that comprises multiple electric quantity parameter sampling module and analog-to-digital conversion module function among the prior art, but structural but can simplify greatly.
Referring to fig. 3, the utility model discloses a CSE 7780's electric energy measurement chip logic component structure, at the chip during operation, the electric current that will sample, voltage signal pass through gain amplifier earlier, amplify the sampled signal, then through the Sigma-Delta of high accuracy, analog-to-digital converter (ADC) convert analog signal into digital signal, and the digital signal who obtains filters high frequency noise and direct current gain through low pass filter, high pass filter to obtain the data of required electric current, voltage sampling quantization. Multiplying the data, and outputting average active power through a low-pass filter; the quantized data of the current and the voltage are used for obtaining effective values of the current and the voltage through a square circuit, a low-pass filter and an open circuit. And integrating the active power according to time to calculate the active energy. The obtained energy is output through a PF pin through an energy frequency converter, and a digital numerical value obtained through digital signal processing can be obtained through an SPI bus.
Claims (5)
1. The utility model provides a photovoltaic harmonic monitoring devices based on electric energy measurement chip which characterized in that: the system comprises a signal input unit, a signal processing unit and a signal processing unit, wherein the signal input unit is used for converting an original voltage signal and an original current signal obtained from a power grid monitoring point into a low voltage signal and a low current signal respectively; the signal conditioning circuit acquires a low-voltage signal and a low-current signal through the signal input unit, and can respectively convert the bipolar low-voltage signal and the bipolar low-current signal into unidirectional sinusoidal signals to be output to the electric energy metering chip; the electric energy metering chip can convert the unidirectional sinusoidal signal into a digital signal, calculate the electric quantity parameter of the photovoltaic power grid, and output the electric quantity parameter to a microprocessor capable of calculating total harmonic distortion according to the electric quantity parameter of the photovoltaic power grid.
2. The photovoltaic harmonic monitoring device based on the electric energy metering chip as claimed in claim 1, wherein: the signal input unit comprises 4 groups of voltage transformers and 4 groups of current transformers; the 4 groups of voltage transformers are used for converting three-phase voltage and zero-sequence voltage of a power grid monitoring point into 4-path low-voltage signals respectively; and the 4 groups of current transformers are used for converting the three-phase current and the zero-sequence current of the power grid monitoring point into 4 paths of low-current signals respectively.
3. The photovoltaic harmonic monitoring device based on the electric energy metering chip as claimed in claim 1, wherein: the signal conditioning circuit comprises an operational amplifier; the inverting input end of the operational amplifier is connected with the ground through a resistor R1, and the inverting input end is connected with the output end through a resistor R2; the non-inverting input terminal of the operational amplifier receives the bipolar input signal through a resistor R3, and a reference voltage is connected between the resistor R3 and the non-inverting input terminal through a resistor R4.
4. The photovoltaic harmonic monitoring device based on the electric energy metering chip as claimed in claim 1, wherein: the model of the electric energy metering chip is CSE 7780.
5. The photovoltaic harmonic monitoring device based on the electric energy metering chip as claimed in claim 1, wherein: the microprocessor is an ARM microprocessor with the model number of LPC 2136.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113466554A (en) * | 2021-06-18 | 2021-10-01 | 国网宁夏电力有限公司电力科学研究院 | Photovoltaic harmonic monitoring system based on electric energy metering chip |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113466554A (en) * | 2021-06-18 | 2021-10-01 | 国网宁夏电力有限公司电力科学研究院 | Photovoltaic harmonic monitoring system based on electric energy metering chip |
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