CN106532948B - Distributed generation resource remote monitoring system and method - Google Patents
Distributed generation resource remote monitoring system and method Download PDFInfo
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- H02J13/0006—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/70—Smart grids as climate change mitigation technology in the energy generation sector
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/12—Monitoring or controlling equipment for energy generation units, e.g. distributed energy generation [DER] or load-side generation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
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Abstract
The present invention relates to a kind of distributed generation resource remote monitoring system and method, master device receives downlink control instruction, and downlink control instruction is modulated to obtain modulation downlink control instruction and is sent to monitoring terminal；Monitoring terminal receives modulation downlink control instruction, modulation downlink control instruction is demodulated to obtain downlink control instruction, and the operating parameter of distributed generation resource is acquired to obtain uplink signal according to downlink control instruction, uplink signal is modulated to obtain modulation uplink signal and is sent to master device；The modulation uplink signal that master device acquisition monitoring terminal is sent obtains the modulation time domain of modulation uplink signal；Modulation uplink signal is demodulated according to the modulation time domain of modulation uplink signal, obtains operating parameter and the output of distributed generation resource.The modulation time domain of uplink signal is modulated by acquisition, avoids and operation is interfered with each other existing for multiplexing, effectively increases uplink signal transmissions rate, monitoring efficiency is high.
Description
Technical Field
The invention relates to the field of power monitoring, in particular to a distributed power supply remote monitoring system and a distributed power supply remote monitoring method.
Background
The distributed power supply has the advantages of decentralized development, on-site network power supply, low cost and the like, and is a beneficial supplement for a large power grid. The small hydropower station is a natural distributed renewable energy source and has a plurality of advantages, but after the small hydropower station is connected to the power grid, the small hydropower station can affect the power quality, the reliability, the trend direction, the network loss and the relay protection of the power grid.
For the remote monitoring of the distributed power supply through 10kV and grid connection, an information transmission channel with high cost performance is a key link, the main communication modes of the power distribution network at present comprise means of optical fibers, public and special wireless, medium-voltage and low-voltage power line carriers and the like, and the remote monitoring of the distributed power supply such as photovoltaic and the like is carried out by depending on the existing power communication platform at present.
However, in the conventional distributed power source remote monitoring method, a signal sent by a remote monitoring terminal is received and demodulated to obtain and display distributed power source data. When multiple signals are received simultaneously, mutual interference operation existing in multiple paths of transmission influences data processing efficiency, received distributed power data cannot be displayed in time, and the traditional distributed power remote monitoring method has the defect of low monitoring efficiency.
Disclosure of Invention
In view of the above, it is necessary to provide a distributed power remote monitoring system and method with high monitoring efficiency.
A distributed power supply remote monitoring system comprises a main station device and a monitoring terminal, wherein the main station device is connected with the monitoring terminal, and the monitoring terminal is connected with a distributed power supply;
the master station equipment is used for modulating the downlink control instruction according to the received downlink control instruction to obtain a modulated downlink control instruction and sending the modulated downlink control instruction to the monitoring terminal; the monitoring terminal is used for acquiring the modulated uplink signal sent by the monitoring terminal, acquiring a modulation time domain of the modulated uplink signal, demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output operation parameters of the distributed power supply;
the monitoring terminal is used for demodulating the modulation downlink control instruction according to the received modulation downlink control instruction to obtain the downlink control instruction, acquiring the operation parameters of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulating the uplink signal and sending the uplink signal to the master station equipment.
A distributed power supply remote monitoring method comprises the following steps:
the method comprises the steps that a master station device receives a downlink control instruction, modulates the downlink control instruction to obtain a modulated downlink control instruction and sends the modulated downlink control instruction to a monitoring terminal;
the monitoring terminal receives the modulation downlink control instruction, demodulates the modulation downlink control instruction to obtain the downlink control instruction, collects the operation parameters of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulates the uplink signal to obtain a modulation uplink signal and sends the modulation uplink signal to the master station equipment;
the master station equipment acquires the modulated uplink signal sent by the monitoring terminal to obtain a modulation time domain of the modulated uplink signal;
and demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output the operation parameters of the distributed power supply.
In the distributed power supply remote monitoring system and the method, the master station equipment receives the downlink control instruction, modulates the downlink control instruction to obtain a modulated downlink control instruction and sends the modulated downlink control instruction to the monitoring terminal; the monitoring terminal receives the modulation downlink control instruction, demodulates the modulation downlink control instruction to obtain a downlink control instruction, collects the operation parameters of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulates the uplink signal to obtain a modulation uplink signal and sends the modulation uplink signal to the master station equipment; the method comprises the steps that a master station device collects a modulated uplink signal sent by a monitoring terminal and obtains a modulation time domain of the modulated uplink signal; demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output the operation parameters of the distributed power supply; after the master station device detects the modulated uplink signal sent by the monitoring terminal, the modulation time domain of the modulated uplink signal is obtained, and the modulated uplink signal is demodulated according to the modulation time domain of the modulated uplink signal, so that mutual interference operation existing in multipath transmission is avoided, the transmission rate of the modulated uplink signal is effectively improved, and the monitoring efficiency of the distributed power supply is high.
Drawings
FIG. 1 is a diagram of a distributed power remote monitoring system according to an embodiment;
FIG. 2 is a flow diagram of a distributed power remote monitoring method according to an embodiment;
FIG. 3 is a diagram of an embodiment of an encoding structure for power frequency communication transmission;
FIG. 4 is a waveform diagram of a signal with white noise according to an embodiment;
FIG. 5 is a signal waveform diagram under the color noise environment according to an embodiment.
Detailed Description
In one embodiment, as shown in fig. 1, a distributed power supply remote monitoring system includes a master station device 110 and a monitoring terminal 120, where the master station device 110 is connected to the monitoring terminal 120, and the monitoring terminal 120 is connected to a distributed power supply 200; the master station device 110 is configured to modulate the downlink control instruction according to the received downlink control instruction to obtain a modulated downlink control instruction, and send the modulated downlink control instruction to the monitoring terminal 120; the system is used for acquiring the modulated uplink signal sent by the monitoring terminal 120, acquiring a modulation time domain of the modulated uplink signal, demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal, obtaining and outputting the operation parameter of the distributed power supply 200; the monitoring terminal 120 is configured to demodulate the modulation downlink control instruction according to the received modulation downlink control instruction to obtain a downlink control instruction, acquire an operation parameter of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulate the uplink signal, and send the uplink signal to the master station device 110.
Specifically, the distributed power supply 200 can control the power utilization time and the load size, actively cooperate with the demand response strategy of the marketer, and can be completely separated from the power grid, even reversely deliver power to the power grid.
In one embodiment, the monitoring terminal 120 includes a sensor module, a processor module, a signal driving module, and a compensation capacitor and driving module, wherein the sensor module, the signal driving module, and the compensation capacitor and driving module are all connected to the processor module, and the sensor module is further connected to the distributed power supply 200; the sensor module is used for receiving a downlink control instruction output by the processor module, acquiring data of the distributed power supply 200 according to the downlink control instruction and sending the data to the processor module; the signal driving module is used for receiving and modulating the downlink control instruction to demodulate, obtaining the downlink control instruction and sending the downlink control instruction to the processor module; receiving the uplink signal output by the processor module, modulating the uplink signal to obtain a modulated uplink signal, and sending the modulated uplink signal to the master station device 110; the processor module is used for sending a downlink control instruction to the sensor module, receiving a signal sent by the sensor module, processing the signal to obtain an uplink signal, outputting the uplink signal to the signal driving module, and driving the compensation capacitor and the driving module to perform reactive compensation on the distributed power supply 200 according to the acquired data of the distributed power supply 200.
Specifically, voltage and current signals from the sensor module are converted by an A/D device in the processor module and then received by an MCU in the processor module, the MCU simultaneously completes TWACS signal processing and calculation of the operation parameters of the distributed power supply 200 through software operation, when information needs to be returned, the MCU in the processor module controls a TWACS signal driving module to perform uplink signal modulation, and switching of the compensation capacitor is controlled according to the reactive processing condition. The modulation and demodulation method of the power frequency communication signal of the power line is realized by performing digital signal processing operation through the MCU.
In one embodiment, the monitoring terminal 120 further includes a power module coupled to the sensor module, the signal driver module, the compensation capacitor and driver module, and the processor module, the power module being configured to provide power to the sensor module, the signal driver module, the compensation capacitor and driver module, and the processor module.
Specifically, the specific form of the power module is not exclusive, and the power module can be a power supply directly attached to a printed circuit board, and is characterized by supplying power to an application specific integrated circuit, a digital signal processor, a microprocessor, a memory, a Field Programmable Gate Array (FPGA) and other digital or analog loads.
In one embodiment, the monitor terminal 120 further includes a clock and memory module coupled to the processor module for outputting a clock signal to the processor module and storing data received by the processor module.
Specifically, in the aspect of electrical measurement, the MCU obtains voltage and current signals through an ac sampling method, and then obtains various electrical parameters of the distributed power supply 200 through software operation, and the positive and negative of active and reactive power need to be determined due to the existence of bidirectional power supply in the distributed power supply 200.
In particular, the voltage or current signal may be approximately expressed as:
wherein n 'is the harmonic frequency of the voltage or current signal, and when n' is 1, the harmonic frequency represents a power frequency fundamental wave.
The computational expression for the amplitude and phase of a signal at any frequency can be expressed as:
wherein:
wherein A isn'、Bn'The cosine coefficient and the sine coefficient of the N ' harmonic of the voltage or the current are respectively, N ' is the number of signal sampling points in 1 power frequency period, k ' is the serial number of the sampling point, and 40 points are adopted for calculation in the embodiment for the power frequency fundamental wave.
The power factor angle is:
wherein,is the initial phase angle of the voltage phasor,is the initial phase angle of the current phasor,is the power factor angle.
Therefore, the directions of active power and reactive power can be judged through the positive and negative of the power factor angle, the electric energy metering characteristics of the distributed power supply 200 are adapted, and forward and reverse active and reactive electric energy can be obtained by combining a classical area integration method.
Considering the problem of island detection of grid connection of the distributed power supply 200, data such as voltage, frequency and the like of the power supply need to be obtained quickly, and the power supply state of the main network is judged, so that whether the main network is cut off or not is determined to be in an island operation mode.
The calculation of the voltage is mature, the difficult problem is the fast calculation of the frequency, and in this embodiment, based on the fourier algorithm, the following frequency calculation method is proposed by using the relationship between the phase and the frequency:
wherein f isGIn order to be the frequency of the radio,the voltage phase of the mth power frequency cycle is calculated on the basis of 50 Hz.
In the remote monitoring system of the distributed power supply 200, the master station device 110 is configured to modulate the downlink control instruction according to the received downlink control instruction to obtain a modulated downlink control instruction, and send the modulated downlink control instruction to the monitoring terminal 120; and the time domain demodulation module is configured to, after detecting the modulated uplink signal sent by the monitoring terminal 120, obtain a modulation time domain of the modulated uplink signal, demodulate the modulated uplink signal according to the modulation time domain of the modulated uplink signal, obtain an operation parameter of the distributed power supply 200, and output the operation parameter; the monitoring terminal 120 is configured to demodulate the modulated downlink control instruction according to the received modulated downlink control instruction to obtain a downlink control instruction, form an uplink signal according to the downlink control instruction, modulate the uplink signal, and send the modulated uplink signal to the master station device 110. After the main station device 110 detects the modulated uplink signal sent by the monitoring terminal 120, the modulation time domain of the modulated uplink signal is obtained, the modulated uplink signal is demodulated according to the modulation time domain of the modulated uplink signal, the mutual interference operation existing in multipath transmission is avoided, the transmission rate of the modulated uplink signal is effectively improved, the monitoring efficiency of the distributed power supply 200 is high, a power supply company can conveniently and effectively master the operation condition of the distributed power supply 200 at low cost, the remote monitoring terminal 120 takes devices such as a MCU (microprogrammed control unit), an AD (analog-to-digital), a PT (potential Transformer) and a CT (computed tomography) as platforms, the monitoring management and power frequency communication functions of the distributed power supply 200 are simultaneously realized through software operation, the device cost is low, and favorable conditions are.
In one embodiment, as shown in fig. 2, a distributed power source remote monitoring method includes the following steps:
step S110: the master station device 110 receives the downlink control instruction, modulates the downlink control instruction to obtain a modulated downlink control instruction, and sends the modulated downlink control instruction to the monitoring terminal 120.
Specifically, the signal from the master station device 110 to the monitor terminal 120 is a downlink signal, and voltage modulation is performed near the voltage zero crossing. In the present embodiment, the communication between the master station device 110 and the monitoring terminal 120 is realized based on a power line communication technology.
Specifically, power line power frequency communication refers to a communication mode that a tiny distortion signal is generated when power line transmission passes through a power grid power frequency voltage zero crossing point to transmit information, can span over a transformer for remote communication, achieves transmission of remote monitoring information of the distributed power supply 200, has the advantages of strong anti-attenuation capacity and no need of installing coupling equipment on a 10KV line, and can adapt to the environment that the distributed power supply 200 is wide in regional distribution and is prone to public wireless network signal blind areas in remote positions. Because the current internal enterprise network of the power system is basically covered to the substation, relevant departments of the power company can conveniently master the operation data of the distributed power supply 200, more accurate basis is provided for tide and protection calculation, and favorable conditions are created for planning of the micro-grid.
Step S120: the monitoring terminal 120 receives the modulated downlink control instruction, demodulates the modulated downlink control instruction to obtain a downlink control instruction, acquires the operating parameters of the distributed power supply 200 according to the downlink control instruction to obtain an uplink signal, modulates the uplink signal to obtain a modulated uplink signal, and transmits the modulated uplink signal to the master station device 110.
Specifically, the signal from the monitor terminal to the master station device 110 is called an upstream signal, and current modulation is performed near the voltage zero crossing. The monitoring terminal has both TWACS and electrical measurement functions, and when receiving the downlink control instruction, the monitoring terminal acquires the operation parameters of the distributed power supply 200, such as the voltage, the current, the active and reactive power generation amounts, the power factor, and the like of the distributed power supply 200 to obtain an uplink signal, modulates the uplink signal near the voltage zero crossing to obtain a modulated uplink signal, and transmits the modulated uplink signal to the master station device 110.
Step S130: the master station device 110 collects the modulated uplink signal sent by the monitoring terminal 120, and obtains a modulation time domain of the modulated uplink signal. In the present embodiment, step S130 includes steps 131 to 135.
Specifically, when the power frequency communication technology is applied to remote monitoring of the distributed power supply 200, the advantages are provided, but the main defect is that the communication rate is low, and for monitoring of the distributed power supply 200, downlink information is relatively less, and only the transmission efficiency of uplink information needs to be improved. According to the mechanism of the power distribution network structure and power frequency communication of the power line, multi-channel transmission of power frequency communication signals is carried out in modes of multi-feeder parallel demodulation, three-phase simultaneous transmission, single-phase multi-channel and the like, so that the equivalent rate of the system is improved.
The power frequency communication uplink demodulation is realized by identifying distortion currents from all distributed power supplies 200 in a 10KV line, and because currents of all 10KV branch lines are basically not influenced with each other, a distributed receiving mode is adopted in a main station device 110 located in a substation, and simultaneously, uplink current signals of all the branch lines are sampled to perform signal detection, so that multi-feeder line parallel demodulation can be realized.
For three-phase simultaneous transmission and single-phase multi-path parallel transmission, due to factors such as line impedance and load, a system voltage phase difference exists between uplink signal receiving and transmitting nodes, and a receiving time domain deviation problem exists in a traditional power frequency communication mode based on local voltage zero crossing.
Aiming at the requirement, a power frequency communication transmission coding structure shown in fig. 3 is designed.
Each bit of downlink data is represented by a voltage distortion signal position of 2 power frequency periods, and each bit of uplink data is represented by a current distortion signal position of 4 power frequency periods; let T be the power frequency cycle, downlink data be M bits, uplink data be N bits, and synchronization information be K bits.
Step 131: and acquiring synchronous information and preamble information of the modulated uplink signal and a current sampling signal of a power frequency period of the modulated uplink signal.
Step 132: and modulating the synchronous information and the preamble information of the modulated uplink signal to obtain a modulation component of the synchronous information and a modulation component of the preamble information.
Specifically, for the case of parallel transmission of multiple uplink signals, since each uplink signal may come from a different transformer, the master station device 110 needs to determine the modulation time domain of each uplink signal according to the preamble information, and the present invention selects and selects the pseudo-random sequence with the length of 31 and the differential manchester code to modulate the synchronization information, in this embodiment, the modulation components of the synchronization information are as follows:
wherein, XI(t) is a modulation component of the synchronization information, IxjAnd (t) is distortion current of the j path, M (t) is Manchester coding, p (k) is a bipolar pseudo-random sequence, N is the coding length of the synchronous information, and j is the number of paths of the signal.
Step 133: and grouping the current sampling signals of the power frequency period of the modulated uplink signal to obtain corresponding adjacent period difference signals.
Specifically, the master station device 110 samples an uplink signal of a 10kV line, divides voltage or current sampling signals of 2N power frequency periods into N groups, and samples signals of two periods in each group, thereby obtaining N adjacent period difference signals.
Step 134: and obtaining a composite signal according to the modulation component of the synchronous information, the adjacent period difference signal and the modulation component of the preamble information of the modulated uplink signal.
Then the N difference signals are weighted with the modulation component of the leading information and then superposed to generate a composite signal, wherein the j-th composite signal can be represented as CjAnd (t), setting I (t) as a current sampling signal.
Wherein, Cj(t) is the j-th composite signal, MD(t) is Manchester decoding, pj(k) And I (t) is a current sampling signal.
Substituting equation (8) into equation (9) yields:
Cj(t)＝N*Ix(t+Δj)+n(t) (10)
wherein, DeltajFor the voltage zero-crossing time difference of each uplink signal receiving and transmitting terminal, IxN (t) is the distortion current, N (t) is the noise, and N is the code length of the synchronization information.
Because the modulation coding of each path of uplink synchronous information has the characteristics of strong autocorrelation and low cross correlation, the synchronous information of the jth path can obtain strong N multiplication, and other 5 paths of preamble information cannot. Therefore, in the synthesized signal generated in the receiving process of each path of communication information, the signal-to-noise ratio is obviously increased, and because the frequency range of the uplink current distortion signal is between 150Hz and 500Hz, the energy of the frequency range is obviously stronger than that of other time periods in the time domain of the modulated uplink signal, the time domain of the modulated signal can be determined through time-frequency analysis.
Step 135: and performing time-frequency analysis on the synthesized signal by adopting the Wigner distribution to determine a modulation time domain for modulating the uplink signal.
Specifically, since the wigner distribution has a high time-frequency resolution, in this embodiment, the time-frequency analysis is performed to determine the signal time domain by using the wigner distribution that suppresses the cross influence.
Wherein, Cj(t) is the composite signal, τ is the variable, t is the time, and h (t) is the rectangular data window.
During uplink communication, because the modulation component in the synchronization information is greatly enhanced, an obvious peak moment appears in the distribution characteristic of the distorted signal energy along with time obtained in the step (4), and the influence of the voltage phase difference of the transmitting and receiving ends of the power frequency communication signal can be overcome by detecting the uplink signal by taking the moment as a reference.
Step S140: and demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output the operation parameter of the distributed power supply 200. In the present embodiment, step S140 includes step 142 and step 144.
Specifically, after the modulation time domain of each uplink signal is determined, signal detection is performed according to the coding mode of each channel of data, the traditional uplink signal detection mode is realized by judging the positive and negative of a differential accumulated value according to a current sampling signal in a voltage zero-crossing region, the time domain characteristics of a distorted signal are not fully utilized, and the anti-interference capability is influenced. The cross-correlation mode is to realize data demodulation according to the positive and negative cross-correlation parameters of the data synthesis signal obtained by reference signal and time domain difference on the basis of removing power frequency and integer harmonic interference by a time domain difference mode according to modulation codes, and the performance is better when the residual power grid noise in the data synthesis signal belongs to white noise.
When the method is applied to monitoring of the distributed power supply 200, a large amount of colored interference noise is generated in a power grid due to the fact that a large amount of power electronic devices are used in the existing microgrid, and therefore the demodulation result of the microgrid can be influenced.
In this embodiment, the current signals in 4 periods are subjected to superposition synthesis operation by modulation coding of uplink data, so that the modulation signals can be approximate to 150Hz sinusoidal signals of 1 period, and then the phase parameters are calculated by adopting wavelet transformation to realize data demodulation.
Step 142: and detecting the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain a detection result. In this embodiment, step 142 includes step 1422, step 1424, and step 1426.
Step 1422: and acquiring current sampling signals of the modulated uplink signals in each power frequency period.
Specifically, after determining the modulation time domain of each uplink signal through the synchronization information and the preamble information, in the data information period, the orthogonal coding mode may implement parallel transmission of 6 uplink signals, and when the E uplink signal is transmitted (E is maximum 6), the sampling currents in 4 power frequency cycles may be represented as:
akifor modulation coding of each uplink signal, Ikp(t) current distortion of the kth signal, Is(T) is background current, k is multi-channel data information based on orthogonal coding, the maximum channel number E is 6, T is power frequency period, each channel of signal has detection vector at ith voltage zero crossing moment, and has +/-1 value, and modulation coding a is utilizedkiAnd the orthogonal relation between the detection vectors can realize the parallel demodulation of multi-channel signals, but the mutual interference of zero is only an ideal state, and in fact, residual interference exists, so that the uplink detection performance needs to be improved to ensure the transmission quality of monitoring information.
Step 1424: and carrying out superposition synthesis operation on the current sampling signals of the modulated uplink signals in each power frequency period to obtain superposition synthesis signals. In this embodiment, step 1424 includes obtaining noise of the modulated uplink signal, and synthesizing the current sampling signals within each power frequency period of the modulated uplink signal to obtain a sinusoidal signal.
Specifically, after data modulation information of each path of uplink signals is acquired through a detection vector, g (t) is set as a rectangular window function with a voltage zero crossing as a center, the time length of the rectangular window function is 3ms, and current modulation signals in 4 periods can be synthesized into sine signals approximate to 150Hz according to the formula (13).
Y (T) is a sinusoidal signal, I (T) is a current sampling signal, g (T) is a rectangular window function with a voltage zero crossing as the center, and T is a power frequency period.
Adding the noise of the sinusoidal signal and the modulated uplink signal to obtain a superposed composite signal:
yI(t)＝ix(t)+nI(t) (14)
wherein n isI(t) is noise, ix(t) is an approximate 150Hz sinusoidal signal, yIAnd (t) is the superposed composite signal.
Step 1426: and calculating the phase parameter of the superposed and synthesized signal by a wavelet transform method, and judging the positive and negative of the phase parameter to obtain a detection result.
Specifically, in order to improve the uplink data detection performance, in this embodiment, the inphase component and the orthogonal component of the discretized complex wavelet mother function are selected as follows:
wherein M is1The length of the data window is selected to be 64, N in this embodiment1Is oneThe total number of samples in the synthesized waveform of approximately 150Hz is selected to be 64 in this embodiment, n is a discrete series of serial numbers, and μ is a high frequency attenuation parameter for controlling the attenuation of the high frequency components in the signal.
The orthogonal component output of the wavelet transform is as follows:
wherein, WRFor superimposing the phase parameters of the composite signal, n being a discrete series of numbers, yI(n) is a superimposed composite signal, phiR(n) is the orthogonal component of the mother function of the discretized complex wavelet.
Step 144: and demodulating the modulated uplink signal according to the detection result.
Specifically, when data demodulation is performed based on the phase parameter, since there are only two phases, data demodulation can be realized only by judging the positive and negative of the quadrature component.
By judging WRThe data demodulation can be realized by only calculating signals of 1 cycle, the high-frequency attenuation parameter mu is selected to be 6, and when the mu is 0, the orthogonal component is obtained by equivalent to short-time Fourier transform.
In order to analyze the performance of wavelet demodulation, n (t) is set to be white gaussian noise, and in the case of different signal-to-noise ratios, the waveform of the received signal shown in equation (14) is as shown in fig. 4, and when 200 points are sampled every power frequency cycle, the useful component of the composite signal occupies a time of about 64 sampling intervals.
For the signal as shown in fig. 4, when the signal-to-noise ratio is high, all of the 3 detection methods can perform demodulation accurately, and when the signal-to-noise ratio is low, demodulation errors occur in the conventional uplink detection method.
Due to the complex harmonic components in the current of the distributed power supply 200 operating site, the single-frequency signal is selected to simulate the site color noise interference condition, and the waveform of the received signal is as shown in fig. 5 under the condition of different signal-to-noise ratios.
The detection performance under different signal-to-noise ratios is contrastively analyzed, the Fourier mode is superior to the traditional uplink detection mode, the performance of wavelet demodulation is superior to the Fourier transform mode, the main reason is that the traditional uplink detection mode realizes demodulation through simple accumulation operation, the time domain characteristics of signals are not fully utilized, the performance of the wavelet demodulation is superior to the Fourier transform mode and can restrain high-frequency interference, and the signal demodulation performance can be effectively improved based on the parallel demodulation mode of the multi-channel uplink signals of the wavelet analysis.
In the remote monitoring method for the distributed power supply, the master station device 110 receives the downlink control instruction, modulates the downlink control instruction to obtain a modulated downlink control instruction, and sends the modulated downlink control instruction to the monitoring terminal 120; the monitoring terminal 120 receives the modulation downlink control instruction, demodulates the modulation downlink control instruction to obtain a downlink control instruction, acquires the operation parameters of the distributed power supply 200 according to the downlink control instruction to obtain an uplink signal, modulates the uplink signal to obtain a modulation uplink signal, and transmits the modulation uplink signal to the master station device 110; after detecting the modulated uplink signal sent by the monitoring terminal 120, the master station device 110 obtains a modulation time domain of the modulated uplink signal; demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output the operation parameters of the distributed power supply 200; after the master station device 110 detects the modulated uplink signal sent by the monitoring terminal 120, the modulation time domain of the modulated uplink signal is obtained, and the modulated uplink signal is demodulated according to the modulation time domain of the modulated uplink signal, so that mutual interference operation existing in multipath transmission is avoided, the transmission rate of the modulated uplink signal is effectively improved, and the monitoring efficiency of the distributed power supply 200 is high.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. The distributed power supply remote monitoring system is characterized by comprising a master station device and a monitoring terminal, wherein the master station device is connected with the monitoring terminal, and the monitoring terminal is connected with a distributed power supply;
the master station equipment is used for modulating the downlink control instruction according to the received downlink control instruction to obtain a modulated downlink control instruction and sending the modulated downlink control instruction to the monitoring terminal; the monitoring terminal is used for acquiring the modulated uplink signal sent by the monitoring terminal, acquiring a modulation time domain of the modulated uplink signal, demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output operation parameters of the distributed power supply;
the monitoring terminal is used for demodulating the modulation downlink control instruction according to the received modulation downlink control instruction to obtain the downlink control instruction, acquiring the operation parameters of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulating the uplink signal and sending the uplink signal to the master station equipment;
the acquiring, by the master station device, the modulated uplink signal sent by the monitoring terminal, and the modulation time domain of the modulated uplink signal includes: acquiring synchronous information and leading information of the modulated uplink signal and a current sampling signal of a power frequency period of the modulated uplink signal; modulating the synchronous information and the preamble information of the modulated uplink signal to obtain a modulation component of the synchronous information and a modulation component of the preamble information; grouping the current sampling signals of the power frequency period of the modulated uplink signal to obtain corresponding adjacent period difference signals; obtaining a composite signal according to the modulation component of the synchronous information, the adjacent period difference signal and the modulation component of the preamble information of the modulated uplink signal; performing time-frequency analysis on the synthesized signal by adopting the Wigner distribution to determine a modulation time domain of the modulated uplink signal; wherein, the modulation component of the synchronous information is:
wherein, XI(t) is a modulation component of the synchronization information, IxjAnd (t) is distortion current of the j path, M (t) is Manchester coding, p (k) is a bipolar pseudo-random sequence, N is the coding length of the synchronous information, and j is the number of paths of the signal.
2. The distributed power supply remote monitoring system according to claim 1, wherein the monitoring terminal comprises a sensor module, a processor module, a signal driving module and a compensation capacitor and driving module, the sensor module, the signal driving module and the compensation capacitor and driving module are all connected with the processor module, and the sensor module is further connected with the distributed power supply;
the sensor module is used for receiving a downlink control instruction output by the processor module, acquiring data of the distributed power supply according to the downlink control instruction and sending the data to the processor module;
the signal driving module is used for receiving the modulated downlink control instruction for demodulation to obtain the downlink control instruction and sending the downlink control instruction to the processor module; receiving the uplink signal output by the processor module for modulation to obtain a modulated uplink signal and sending the modulated uplink signal to the master station equipment;
the processor module is used for sending the downlink control instruction to the sensor module, receiving and processing the signal sent by the sensor module, obtaining an uplink signal and outputting the uplink signal to the signal driving module, and driving the compensation capacitor and the driving module to perform reactive compensation on the distributed power supply according to the collected data of the distributed power supply.
3. The distributed power remote monitoring system according to claim 2, wherein the monitoring terminal further comprises a power module connected to the sensor module, the signal driving module, the compensation capacitor and driving module and the processor module, the power module being configured to supply power to the sensor module, the signal driving module, the compensation capacitor and driving module and the processor module.
4. The distributed power supply remote monitoring system according to claim 2, wherein the monitoring terminal further comprises a clock and storage module connected to the processor module, the clock and storage module being configured to output a clock signal to the processor module and store data received by the processor module.
5. A distributed power supply remote monitoring method is characterized by comprising the following steps:
the method comprises the steps that a master station device receives a downlink control instruction, modulates the downlink control instruction to obtain a modulated downlink control instruction and sends the modulated downlink control instruction to a monitoring terminal;
the monitoring terminal receives the modulation downlink control instruction, demodulates the modulation downlink control instruction to obtain the downlink control instruction, collects the operation parameters of the distributed power supply according to the downlink control instruction to obtain an uplink signal, modulates the uplink signal to obtain a modulation uplink signal and sends the modulation uplink signal to the master station equipment;
the master station equipment acquires the modulated uplink signal sent by the monitoring terminal to obtain a modulation time domain of the modulated uplink signal;
demodulating the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain and output operation parameters of the distributed power supply;
the master station equipment acquires the modulated uplink signal sent by the monitoring terminal and acquires a modulation time domain of the modulated uplink signal, and the method comprises the following steps:
acquiring synchronous information and leading information of the modulated uplink signal and a current sampling signal of a power frequency period of the modulated uplink signal;
modulating the synchronous information and the preamble information of the modulated uplink signal to obtain a modulation component of the synchronous information and a modulation component of the preamble information;
grouping the current sampling signals of the power frequency period of the modulated uplink signal to obtain corresponding adjacent period difference signals;
obtaining a composite signal according to the modulation component of the synchronous information, the adjacent period difference signal and the modulation component of the preamble information of the modulated uplink signal;
performing time-frequency analysis on the synthesized signal by adopting the Wigner distribution to determine a modulation time domain of the modulated uplink signal;
wherein, the modulation component of the synchronous information is:
wherein, XI(t) is a modulation component of the synchronization information, IxjAnd (t) is distortion current of the j path, M (t) is Manchester coding, p (k) is a bipolar pseudo-random sequence, N is the coding length of the synchronous information, and j is the number of paths of the signal.
6. The distributed power remote monitoring method according to claim 5, wherein the step of demodulating the modulated uplink signal according to the modulated time domain of the modulated uplink signal comprises:
detecting the modulated uplink signal according to the modulation time domain of the modulated uplink signal to obtain a detection result;
and demodulating the modulated uplink signal according to the detection result.
7. The distributed power supply remote monitoring method according to claim 6, wherein the step of detecting the modulated uplink signal according to the modulated time domain of the modulated uplink signal to obtain a detection result comprises:
acquiring current sampling signals of the modulated uplink signals in each power frequency period;
carrying out superposition synthesis operation on the current sampling signals in each power frequency period of the modulated uplink signals to obtain superposed synthesis signals;
and calculating the phase parameter of the superposed and synthesized signal by a wavelet transform method, and judging the positive and negative of the phase parameter to obtain a detection result.
8. The distributed power supply remote monitoring method according to claim 7, wherein the step of performing superposition synthesis operation on the current sampling signals in each power frequency period of the modulated uplink signal to obtain a superposition synthesis signal comprises:
acquiring noise of the modulated uplink signal;
synthesizing the current sampling signals of the modulated uplink signals in each power frequency period to obtain sinusoidal signals;
and adding the noise of the sinusoidal signal and the modulated uplink signal to obtain a superposed composite signal.
9. The distributed power supply remote monitoring method according to claim 8, wherein the step of calculating the phase parameter of the superimposed composite signal by means of wavelet transform comprises:
WR＝yI(n)*φR(n)
wherein, WRFor superimposing the phase parameters of the composite signal, n being a discrete series of numbers, yI(n) is a superimposed composite signal, phiR(n) is the orthogonal component of the mother function of the discretized complex wavelet.
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