A multi-machine variable frequency sampling system and method based on optical fiber

Abstract

The application discloses a kind of multi-machine variable frequency sampling system and method based on optical fiber, the system is based on optical fiber loop communication structure, the host computer includes optical fiber communication module, sampling module and variable frequency algorithm module, the variable frequency algorithm module includes master module and data reorganization module, the master module is according to the highest sampling frequency of system setting sampling frequency and ADC, adaptive adjustment sampling frequency, generates sampling time point, through high-speed optical fiber communication, ensure that host computer and multiple slave machines realize synchronous sampling, the data reorganization module received sampling value is reorganized, and the data sequence according to the order of delay identifier is recovered.The application realizes the function of multi-machine system variable frequency sampling by controlling the time interval of sending optical fiber communication frame, the structure is simple to realize, without changing host computer and each slave machine sampling chip ADC, without additional synchronous clock signal, meet the setting of the sampling rate required by system, complete the measurement of various parameters.

Description

Technical Field

[0001] This invention relates to the field of multi-machine parallel optical fiber communication technology, specifically to a multi-machine frequency conversion sampling system and method based on optical fiber. Background Technology

[0002] In power supply and load systems, current and voltage sampling plays a crucial and indispensable role. In multi-machine systems, high requirements are often placed on sampling frequency and synchronous sampling. The traditional approach involves designing a dedicated clock to synchronously distribute across multiple machines, providing strictly phase-consistent clock and synchronization signals. This is done using a high-sampling-rate ADC, operating at its highest speed, and then slowing down to the required rate. Applications include current sharing monitoring and harmonic calculation. However, in practical engineering, this approach demands high hardware performance, incurs high implementation costs, and the accuracy of the speed-down is limited by the ADC's own sampling frequency. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by designing a fiber optic multi-machine frequency conversion sampling method. The method is characterized by achieving synchronous sampling of multiple machines based on optical fibers and adaptively increasing or decreasing the sampling frequency according to system requirements. Various system indicators can be measured by changing the sampling frequency. This method is easy to implement and has low cost.

[0004] This invention discloses a multi-machine frequency conversion sampling system based on optical fiber, which is based on an optical fiber loop communication structure consisting of a host and multiple slave machines. The host includes an optical fiber communication module, a sampling module, and a frequency conversion algorithm module. The frequency conversion algorithm module adjusts and delays the sampling time point according to the sampling frequency set by the system and the highest sampling frequency of the ADC to generate optical fiber communication sampling time points. At the same time, through high-speed optical fiber communication, the received sampling values ​​are reassembled to restore the data sequence according to the delay identifier order.

[0005] In the aforementioned fiber optic loop communication structure, any one machine can be the master and the others can be slaves; alternatively, one channel module of a machine can be the master and the other channel modules can be slaves.

[0006] The host and multiple slave devices are all equipped with current sampling modules.

[0007] This invention discloses a multi-machine frequency conversion sampling method based on optical fiber, and a multi-machine frequency conversion sampling system based on optical fiber.

[0008] When the required sampling frequency of the system is less than the maximum sampling frequency of the ADC, the system sets the sampling frequency of the system current measurement by controlling the interval between new communication frames initiated by the host.

[0009] When the required sampling frequency of the system is greater than the maximum sampling frequency of the ADC, the steps to achieve multi-machine frequency conversion sampling are as follows:

[0010] Step 1: The host first calculates the sampling time points of the current signal within one cycle but less than two cycles based on the sampling frequency required by the system, and attaches a delay indicator for each sampling time point.

[0011] Step two: Define the moment when the host initiates the first communication frame as the moment when the latest fiber optic communication frame is initiated. The host sequentially reads the sampling time points of the first sampling period. For each value read, the difference between that time point and the moment when the latest fiber optic communication frame is initiated is calculated. If the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC, the host will proceed accordingly. ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0012] Step 3: After the host has traversed all sampling time points of the first current cycle, it begins sampling time points for the next cycle. By judging the delay flag, it determines whether the next cycle is a new sampling cycle or a delayed sampling cycle. The first delayed sampling cycle sampling time points are read sequentially. For each value read, the difference between that time point and the time point when the latest fiber optic communication frame was initiated is calculated. If the difference is greater than the minimum sampling period T corresponding to the ADC's highest sampling frequency... ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0013] Step 4: After the host has traversed all the sampling time points of the first delayed period, it starts the sampling time points of the next period and jumps back to Step 1.

[0014] The host initiates a new current sampling cycle. The receiving module clears the sampling data buffer, waits for the first current sampling value and the delay flag is 0. After the host enters the current sampling value reception, it stores each received current sampling value in the buffer module, reads its delay flag, and records its address. After the current sampling value reception is completed, it enters the current sampling value reassembly, reads a current sampling value from each address in turn, and reassembles it into a new current sampling value sequence.

[0015] The slave device receives the current value transmitted by the host through the optical fiber receiver in the optical fiber communication module, and adds it to the real-time current value collected by its own current sampling module. Then, it sends the summed value to the next slave device through the optical fiber transmitter. After passing through the optical fiber loop, the host receives the summed current value of N machines through the optical fiber receiver, thus completing a multi-machine current measurement.

[0016] The system also includes a voltage sampling module and an impedance calculation module. The voltage sampling module is used to sample the total voltage value of the multi-machine system. The impedance calculation module calculates the AC impedance by acquiring the instantaneous current and voltage values ​​of multiple integer cycles. The voltage sampling module and current sampling module of the host machine perform synchronous sampling according to the set sampling period, and input the voltage sampling data and total current sampling data synchronously into the impedance calculation module. The impedance calculation module acquires the voltage value and total current value of multiple integer cycles, calculates the voltage amplitude and phase and the total current amplitude and phase respectively, and obtains the AC impedance.

[0017] This invention discloses a multi-machine frequency conversion sampling method based on optical fiber. Based on the aforementioned multi-machine frequency conversion sampling system based on optical fiber, the host and multiple slave machines are all equipped with voltage sampling modules.

[0018] When the required sampling frequency of the system is less than the maximum sampling frequency of the ADC, the system sets the sampling frequency of the system voltage measurement by controlling the interval between new communication frames initiated by the host.

[0019] When the required sampling frequency of the system is greater than the maximum sampling frequency of the ADC, the steps to achieve multi-machine frequency conversion sampling are as follows:

[0020] Step 1: The host first calculates the sampling time points of the voltage signal within one cycle but less than two cycles based on the sampling frequency required by the system, and attaches a delay indicator for each sampling time point.

[0021] Step two: Define the moment when the host initiates the first communication frame as the moment when the latest fiber optic communication frame is initiated. The host sequentially reads the sampling time points of the first sampling period. For each value read, the difference between that time point and the moment when the latest fiber optic communication frame is initiated is calculated. If the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC, the host will proceed accordingly. ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0022] Step 3: After the host has traversed all sampling time points of the first voltage cycle, it begins sampling time points for the next cycle. By judging the delay flag, it determines whether the next cycle is a new sampling cycle or a delayed sampling cycle. It then sequentially reads the sampling time points of the first delayed sampling cycle. For each value read, it calculates the difference between that time point and the time point when the latest fiber optic communication frame was initiated. If the difference is greater than the minimum sampling period T corresponding to the ADC's highest sampling frequency... ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0023] Step 4: After the host has traversed all the sampling time points of the first delayed period, it starts the sampling time points of the next period and jumps back to Step 1.

[0024] The beneficial effects of the technical solution of this invention are as follows:

[0025] 1. This invention employs a high-speed fiber optic loop topology to transmit the sum of current / voltage values ​​from a multi-machine system. The communication frame passes through each slave unit in the system, accumulating the real-time current / voltage of that slave unit, and then returns to the master unit after traversing the entire fiber optic loop to obtain the total current / voltage of the system. This method minimizes communication overhead while ensuring high measurement accuracy and real-time performance.

[0026] 2. The host of this invention realizes the frequency conversion sampling function of a multi-machine system by controlling the time interval of sending optical fiber communication frames. The structure is simple to implement. Without changing the ADC of the host and each slave sampling chip, no additional synchronization clock signal is required, which meets the sampling frequency setting required by the system and completes the measurement of various parameters. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the multi-machine frequency conversion sampling system of the present invention.

[0028] Figure 2 This is a schematic diagram of the control sampling period of the multi-machine frequency conversion sampling system of the present invention.

[0029] Figure 3 This is a schematic diagram of the system current sampling points of the present invention.

[0030] Figure 4 This is a schematic diagram of the current sampling points in the first cycle of the frequency conversion algorithm of the present invention.

[0031] Figure 5 This is a schematic diagram of the current sampling points for the frequency conversion algorithm of the present invention.

[0032] Figure 6 This is a schematic diagram of the recombinant sampling data of the present invention.

[0033] Figure 7 This is a schematic diagram illustrating the implementation process of the adaptive synchronous frequency conversion sampling algorithm module of the present invention.

[0034] Figure 8 This is a schematic diagram of the measurement of the total current in the multi-machine frequency conversion system based on the fiber optic loop structure of the present invention.

[0035] Figure 9 This is a schematic diagram of the AC impedance measurement framework of the multi-machine frequency conversion sampling system of the present invention.

[0036] Figure 10 This is a schematic diagram of impedance measurement in the multi-machine frequency conversion sampling system of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will be described in detail below, but the scope of protection of the present invention is not limited to the embodiments described.

[0038] like Figure 1 As shown, this invention discloses a multi-machine frequency conversion sampling system based on optical fiber. The system is based on an optical fiber loop communication structure with one master and multiple slaves. In the optical fiber loop communication structure, any one machine can be the master and the others can be slaves; alternatively, one channel module of one machine can be the master and the other multiple channel modules can be slaves.

[0039] Preferably, the master unit and multiple slave units form a parallel system. The parallel system can be a power supply or a load. The power supply outputs power, mainly for supplying voltage; the load inputs power, mainly for drawing current. This embodiment takes a load as an example.

[0040] The host load includes a fiber optic communication module, a sampling module, and a frequency conversion algorithm module. The frequency conversion algorithm module includes a main control module and a data reconstruction module. The main control module adaptively adjusts the system's sampling frequency based on the system's set sampling frequency and the ADC sampling frequency to generate sampling time points. Simultaneously, high-speed fiber optic communication ensures synchronous sampling across the master and slave loads. The data reconstruction module reassembles the received sampled values ​​to restore a data sequence according to the delayed identifier order. In the multi-machine sampling system, both the host load and each slave load are equipped with a current sampling module, where the highest sampling frequency of the ADC is f. ADC .

[0041] The main control module in the frequency conversion algorithm module receives the sampling frequency f set by the system. sys The highest sampling frequency f of the ADC of the current sampling module ADC By controlling the interval between new fiber optic communication frames initiated by the host load, the sampling frequency of the system measurement can be adjusted and changed. When the required sampling frequency f of the multi-machine system... sys Greater than the highest sampling frequency f of the ADC ADC The main control module first calculates sampling time points that exceed one cycle, and then reads the sampling time points of a complete cycle sequentially, comparing each one to see if it meets the ADC sampling cycle. Time points that meet the cycle are initiated with fiber optic communication frames, completing multi-machine synchronous sampling; time points that do not meet the cycle are postponed to the next cycle, forming the first postponement cycle. This process continues, with time points in the first postponement cycle that meet the ADC sampling cycle triggering fiber optic communication frames, and those that do not are postponed to the next cycle, forming the second postponement cycle, until all sampling time points have been transmitted.

[0042] Meanwhile, the data reconstruction module in the frequency conversion algorithm module acquires sampled data through the optical fiber receiver in the optical fiber communication module. The acquired sampled data carries a delay period identifier. The data reconstruction module groups the sampled data according to the delay period identifier, reads each group of data in turn, and reconstructs it into a new sequence of current sampled values, thus obtaining the current sampled values ​​under the required sampling period of the system.

[0043] This invention also discloses a multi-machine frequency conversion sampling method based on optical fiber, wherein the multi-machine frequency conversion sampling system based on the aforementioned optical fiber, when the required sampling frequency f of the multi-machine system... sys Less than the highest sampling frequency of the ADC, i.e.

[0044] f sys <f ADC

[0045] The system sets the sampling frequency for system current measurement by controlling the interval between new communication frames initiated by the host load.

[0046] like Figure 2 As shown, the host load initiates the first communication frame at time t0, and after an interval of Δt, initiates the second communication frame at time (t+Δt). After another interval of Δt, initiate the third communication frame at time (t+2Δt). And so on, initiating the Kth communication frame at time [t+(k-1)Δt].

[0047] The first communication frame is transmitted via a high-speed fiber optic loop topology, transmitting the accumulated current values ​​of each slave load back to the master load at time t1. That is, the duration of one complete communication frame in a multi-machine system via the fiber optic loop is...

[0048] Tfiber=|t1-t0|

[0049] Among them, the speed of optical fiber communication is as high as 1Gbps, while the sampling frequency of the current sampling module inside a single load device is hundreds of kHz, and the current sampling period is much longer than the duration of optical fiber loop communication.

[0050] Tsample>>Tfiber

[0051] In this embodiment, the current measurement of the multi-machine system based on the fiber optic loop topology is real-time.

[0052] Simultaneously, the host load generates and sends a new current communication frame every interval Δt. Therefore, the communication frames receiving the sum of the multi-machine system currents through the fiber optic loop by the host load are also at intervals of Δt. In other words, the time interval for the host load to obtain discrete sampled values ​​of the total multi-machine system current is Δt, which is the sampling period T of the total system current. sys .

[0053] Δt=T sys=1 / f sys

[0054] Therefore, in this embodiment, by controlling the host load to generate and send new current communication frames at a fixed interval Δt, the sampling frequency of the total current measurement of the multi-machine system can be set.

[0055] However, when the required sampling frequency of a multi-machine system is greater than the maximum sampling frequency of the ADC, i.e.

[0056] f sys >f ADC

[0057] At this point, if the sampling period T required by the system is followed... sys Timed transmission of fiber optic communication frames, due to T sys <T ADC The ADC in the current sampling module is not working properly. Therefore, this embodiment adopts the following steps to realize the multi-machine frequency conversion function through optical fiber communication.

[0058] Step one: The host load first calculates the sampling time points k0, k1, k2... for the current signal that exceed one cycle but less than two cycles based on the system's required sampling frequency, and simultaneously adds a delay flag dy=0 for each sampling time point, such as... Figure 3 As shown.

[0059] Step 2: After the host load initiates the first communication frame at time k0, k0 is defined as the time point K at which the latest fiber optic communication frame is initiated. S K S =k0. Because

[0060] k1-k0=T sys <T ADC

[0061] Add the period T of the current signal to k1 I To obtain the new time k1 delay ,

[0062] k1 delay =k1+T I

[0063] That is, k1 delay This can be viewed as a sampling time where k1 is delayed by one current cycle. Simultaneously, a first delayed sampling cycle is inserted after the first cycle, and k1... delay Insert it into the first delayed sampling period, and set k1 delay The delay flag is incremented by 1, i.e.

[0064] dy1 = dy1 + 1

[0065] Furthermore, all sampling time points that exceeded one cycle in the previously calculated sampling time points were also delayed by one current cycle.

[0066] The host load sequentially reads the sampling time points k2, k3...km of the first cycle. For each value read, it calculates its relationship with the initiation time point K of the latest fiber optic communication frame. S The difference, then compared with the minimum sampling period T corresponding to the highest sampling frequency of the ADC. ADC Make a comparison.

[0067] If k2-K S ≥T ADC Then the host loads the value of k2, waits for time k2, initiates a new communication frame, and simultaneously sends the latest fiber optic communication frame initiation time point K. S Updated to k2.

[0068] If k2-K S <T ADC Then add the period T of the current signal to k2. I To obtain the new time k2 delay ,Right now

[0069] k2 delay =k2+T I

[0070] k2 delay Insert it into the first delayed sampling period, and set k2 delay The delay indicator is incremented by 1. And so on, such as... Figure 4 All sampling time points in the first cycle are divided into two parts. The first part (green dots) has been sampled by the communication frame initiated by the optical fiber, while the second part (red and black dots) is moved into the first delayed cycle, and the delayed indicator is incremented by 1.

[0071] Step 3: After the host load has traversed all sampling moments of the first current sampling cycle, the next sampling cycle begins. First, a delay flag is used to determine whether the next cycle is a new sampling cycle or a delayed sampling cycle.

[0072] If the delay flag dy=0 for the next cycle time point, then it is a new sampling cycle. The sampling time point within one to less than two cycles of the current signal is calculated based on the system's required sampling frequency. To ensure signal continuity, the first sampling time point of the new cycle is the old value calculated in the previous round. Latest fiber optic communication frame initiation time point K. S Do not reset; use the old value. Then proceed to step two.

[0073] If the delay flag dy > 0 for the next cycle time point, then the sampling cycle is delayed, and the host load continues to read the sampling time point ki and calculate its relationship with the latest fiber optic communication frame initiation time point K. SThe difference, then compared with the minimum sampling period T corresponding to the highest sampling frequency of the ADC. ADC Make a comparison.

[0074] If ki-K S ≥T ADC If the host loads the value ki, waits for time ki, initiates a new communication frame, and updates the initiation time of the latest fiber optic communication frame to ki.

[0075] If ki-K S <T ADC If km is the first point in the delayed sampling period that does not meet the sampling period requirement, then another delayed sampling period (let's call it the second delayed sampling period) is inserted after that period, and the period T of the current signal is added to ki. I Convert to ki delay The sample is placed into the second delayed sampling period, and the delay flag of ki is incremented by 1. The corresponding sampling time points after this period are also delayed by one current period.

[0076] The host load sequentially reads delayed sampling period time points k(i+1), k(i+2), ..., and calculates its relationship with the latest fiber optic communication frame initiation time point K after each value is read. S The difference, then compared with the minimum sampling period T corresponding to the highest sampling frequency of the ADC. ADC Make a comparison.

[0077] If k(i+1)-K S ≥T ADC Then the host loads the value k(i+1), waits for time k(i+1), initiates a new communication frame, and simultaneously sends the initiation time point K of the latest fiber optic communication frame. S Update to k(i+1).

[0078] If k(i+1)-K S <T ADC Then add the period T of the current signal to k(i+1). I Convert to k(i+1) delay , and k(i+1) delay When the second delayed sampling period is added, the corresponding delay flag is incremented by 1. This process continues, such as... Figure 5 All sampling time points in the first delay period are divided into two parts. One part (black dots), with delay identifier dy=1, has been sampled by the communication frame initiated by the optical fiber. The other part (red dots) is moved into the second delay sampling period, with delay identifier dy=2.

[0079] Step 4: After the host load has traversed all the sampling times of the first delayed sampling period, start the next sampling time point and jump back to Step 1.

[0080] Following the steps above, the host load initiates a multi-machine synchronous high-frequency sampling function by controlling the time interval of sending fiber optic communication frames and leveraging the high-speed performance of fiber optics. The slave loads receive the current value transmitted by the host load through the fiber optic receiver, simultaneously adding it to the real-time current value collected by their own current sampling module, and then sending the sum to the next slave load through the fiber optic transmitter. After passing through the fiber optic loop, the host load receives the sum of the currents from the N load systems through the fiber optic receiver.

[0081] The sum of the currents received sequentially by the host load corresponds one-to-one with the time point of the fiber optic communication frame initiation, i.e., as shown below. Figure 5 The data points shown are used to reassemble the sampled data according to the following rules based on the host load.

[0082] When the host load initiates a new current sampling, the receiving module first clears the sampling data buffer, waits for the first current sample value, and sets the delay flag dy=0.

[0083] After the host load enters the current sampling value reception, it stores each received current sample value in the buffer module and reads its delay flag. The storage address of the first current sample value with delay flag dy=0 is recorded as address0, and then they are buffered one by one until the first current sample value with delay flag dy=1 is recorded as address1, and so on, until address2, address3, and so on, until the delay flag returns to dy=0 again, at which point one current sampling cycle is determined to be over.

[0084] After the current sampling value is received, the current sampling value reconstruction process begins. For example... Figure 6 As shown, the first current sample value is read from address0, the second from address1, the third from address2, the fourth from address3, and so on. After all addresses have been read once, the process returns to address0+1 to read the fifth current sample value, address1+1 to read the sixth, and so on, reading one current sample value from each address in turn, recombining them into a new sequence of current sample values. This obtains the current sample values ​​for the required sampling period of the system.

[0085] Through the above steps, the host load controls the time interval of sending fiber optic communication frames to realize the frequency conversion sampling function of the multi-machine system. The structure is simple to implement. Without changing the ADC of the sampling chips of the host and each slave load, no additional synchronization clock signal is required to meet the sampling rate setting required by the system and complete the measurement of various parameters.

[0086] In the fiber-optic-based multi-machine frequency conversion sampling method, to achieve adaptive synchronous frequency conversion sampling in the host load, an adaptive synchronous frequency conversion sampling algorithm module needs to be added to the host load. The specific implementation of this algorithm module is as follows: Figure 7 As shown, first obtain the sampling frequency f set by the system. sys and the highest sampling frequency f of the ADC ADC Based on the system sampling frequency, sampling time points k0, k1, k2... exceeding one cycle are calculated, with the delay flag dy=0 for each sampling time point. Then, sampling time points km for a complete cycle are read sequentially, and each is compared to see if it meets the ADC sampling cycle, determining if km-ks≥T. ADC If the conditions are met, a new communication frame is initiated and ks = km; otherwise, km is not met. delay =km+T I dym = dym + 1, and km delay The delayed sampling period is then included. Then, the time intervals (in km) sampled within the delayed sampling period are read sequentially. delay Determine km delay -ks≥T ADC When all delayed sampling time points initiate a communication frame, one cycle of sampling is completed.

[0087] The fiber-optic multi-machine frequency conversion sampling method is widely used, especially in complex systems with high sampling frequency requirements. This invention is not only applicable to sampling the total current in multi-machine load systems, but also to measuring the phase difference of currents in various slave devices. High-speed fiber optic communication ensures the synchronization of multi-channel sampling, and frequency conversion significantly improves the sampling rate of each channel, thereby improving phase accuracy. Furthermore, in harmonic analysis, when performing harmonic analysis using Fast Fourier Transform, the input sampled values ​​are ideally powers of 2. Traditional methods involve zero-padding. However, under a fixed sampling rate, the number of zeros padded varies for different fundamental signals. When the actual number of sampling points deviates significantly from the expected number, zero-padding becomes unsuitable. This invention discloses a frequency conversion sampling method that effectively solves this problem. Selecting the most suitable sampling frequency for data sampling, and relying on the high-speed performance of fiber optics, allows for highly accurate frequency adjustment, all of which greatly improve the accuracy of harmonic analysis measurements.

[0088] like Figure 8As shown, this invention discloses a multi-machine frequency conversion sampling system based on optical fiber, which includes a host and each slave load, as well as a load execution module. The load execution module performs basic functions such as current output of the load according to set values ​​and measured values. The current sampling module is used to collect the output current value of the device in real time. The optical fiber communication module includes an optical fiber transmitter and an optical fiber receiver. The optical fiber receiver receives the current signal transmitted by the upstream load device and adds it to the local current value collected by the current sampling module. Then, the optical fiber transmitter sends the summed current value to the next-level load device. The multi-machine load system connects the optical fiber transmitter of the host load device to the optical fiber receiver of the first slave load through the optical fiber communication module. The optical fiber transmitter of the first slave load is connected to the optical fiber receiver of the second slave load, and so on, connecting each slave load device in series until the optical fiber transmitter of the last slave load device (N-1) is connected to the optical fiber receiver of the host load device, forming an optical fiber loop topology of the multi-machine load system.

[0089] The host load generates a new communication frame, placing the local current value I1, which is collected in real time by the current sampling module, into the communication frame. This frame is then transmitted to the first slave load via the fiber optic transmitter. The first slave load receives the current value I1 transmitted by the host load via the fiber optic receiver and simultaneously reads the real-time current value I2 from its current sampling module. I1 and I2 are added together to obtain the sum of the currents of the two loads, S2.

[0090] S2=I1+I2

[0091] The first slave load replaces the current value I1 of the master load in the communication frame with the sum of the currents of the two loads, S2. After updating the communication frame, it sends it to the second slave load through the optical fiber transmitter.

[0092] After receiving the communication frame through the fiber optic receiver, the second slave load obtains the sum of the currents S2 of the first two loads. Simultaneously, it reads the real-time current value I3 of the second slave load from its current sampling module. S2 and I3 are then added together to obtain the sum of the currents S3 of the first three loads.

[0093] S3 = S2 + I3 = I1 + I2 + I3

[0094] The second slave load replaces the sum of the currents S2 of the first two loads in the communication frame with the sum of the currents S3 of the three loads. After updating the communication frame, it sends it to the third slave load through the optical fiber transmitter.

[0095] Similarly, after the (N-1)th slave load receives the communication frame through the fiber optic receiver, it obtains the sum of the currents Sn-1 of the first N-1 loads. Simultaneously, it reads the real-time current value In of the (N-1)th slave load from its current sampling module. Sn-1 is then added to In to obtain the sum of the currents Sn of the N loads in the multi-machine system.

[0096] Sn=Sn-1+In=I1+I2+I3+………In-1+In

[0097] The (N-1)th slave load replaces the sum of the currents Sn-1 of the previous N-1 loads with the sum of the currents Sn of the N loads, updates the communication frame, and then sends it to the host load of the system through the fiber optic transmitter. After receiving the communication frame from the fiber optic receiver, the host load obtains the sum of the currents Sn of the N loads, thus completing one measurement of the total system current.

[0098] The present invention can also realize a method for measuring the total current of a multi-machine load system by employing an optical fiber loop topology.

[0099] First, in the multi-machine load system, the master load generates a new communication frame and transmits it to the first slave load via its fiber optic transmitter. Upon receiving the communication frame from the master load, the first slave load places the real-time current value I2, read by its local current sampling module, into the communication frame and then transmits it to the second slave load via its fiber optic transmitter. The current information transmitted by the first slave load is...

[0100] S1=I2

[0101] The second slave load receives the current value S1 transmitted by the first slave load through the optical fiber receiver. Simultaneously, it reads the real-time current value I3 of the second slave load from its current sampling module. S1 and I3 are added together to obtain the sum of the currents of the two loads, S2.

[0102] S2 = I2 + I3

[0103] The second slave load replaces the current value S1 in the communication frame with the sum of the currents of the two slave loads, S2. After updating the communication frame, it sends it to the third slave load through the optical fiber transmitter.

[0104] After receiving the communication frame through the fiber optic receiver, the third slave load obtains the sum of the currents S2 of the first two loads. Simultaneously, it reads the real-time current value I4 of the third slave load from its current sampling module. S2 and I4 are then added together to obtain the sum of the currents S3 of the first three loads.

[0105] S3 = S2 + I4 = I2 + I3 + I4

[0106] The third slave load replaces the sum of the currents S2 of the first two loads in the communication frame with the sum of the currents S3 of the three slave loads. After updating the communication frame, it sends it to the fourth slave load through the optical fiber transmitter.

[0107] Similarly, after the (N-1)th slave load receives the communication frame through the fiber optic receiver, it obtains the sum of the currents Sn-2 of the first N-2 loads. Simultaneously, it reads the real-time current value In of the (N-1)th slave load from its current sampling module. Sn-2 is then added to In to obtain the sum of the currents Sn-1 of the N-1 loads in the multi-load system.

[0108] Sn-1=Sn-2+In=I2+I3+………In-1+In

[0109] The (N-1)th slave load replaces the sum of the currents Sn-2 of the first N-2 loads with the sum of the currents Sn-1 of the N-1 slave loads, updates the communication frame, and then sends it to the master load of the system via the fiber optic transmitter. After receiving the communication frame from the fiber optic receiver, the master load obtains the sum of the currents Sn-1 of the N-1 slave loads. Simultaneously, it reads the real-time current value I1 of the master load from its current sampling module, adds Sn-1 to I1, and obtains the sum of the currents Sn of the N loads in the multi-machine system.

[0110] Sn=Sn-1+I1=I2+I3+………In-1+In+I1

[0111] Unlike the previous method of measuring the total current of multiple loads, in this embodiment the communication frame sent by the host load does not contain the current information of the host load. That is, the current of the host load does not participate in the communication of the optical fiber loop, which can save some communication overhead.

[0112] The multi-load system measurement scheme disclosed in this invention adopts a high-speed fiber optic loop topology to transmit the sum of current values ​​of the multi-load system. The communication frame passes through each slave load in the system, adding the real-time current of that slave load, traversing the entire fiber optic loop back to the master load, and obtaining the total system current. This method features low communication overhead while ensuring high measurement accuracy and real-time performance.

[0113] The present invention also discloses a multi-machine frequency conversion sampling method based on optical fiber, and a multi-machine frequency conversion sampling system based on optical fiber, wherein the host and multiple slave machines are equipped with voltage sampling modules;

[0114] When the required sampling frequency of the system is less than the maximum sampling frequency of the ADC, the system sets the sampling frequency of the system voltage measurement by controlling the interval between new communication frames initiated by the host.

[0115] When the required sampling frequency of the system is greater than the maximum sampling frequency of the ADC, the steps to achieve multi-machine frequency conversion sampling are as follows:

[0116] Step 1: The host first calculates the sampling time points of the voltage signal within one cycle but less than two cycles based on the sampling frequency required by the system, and attaches a delay indicator for each sampling time point.

[0117] Step two: Define the moment when the host initiates the first communication frame as the moment when the latest fiber optic communication frame is initiated. The host sequentially reads the sampling time points of the first sampling period. For each value read, the difference between that time point and the moment when the latest fiber optic communication frame is initiated is calculated. If the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC, the host will proceed accordingly. ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0118] Step 3: After the host has traversed all sampling time points of the first voltage cycle, it begins sampling time points for the next cycle. By judging the delay flag, it determines whether the next cycle is a new sampling cycle or a delayed sampling cycle. It then sequentially reads the sampling time points of the first delayed sampling cycle. For each value read, it calculates the difference between that time point and the time point when the latest fiber optic communication frame was initiated. If the difference is greater than the minimum sampling period T corresponding to the ADC's highest sampling frequency... ADC If the sampling time is positive, then that time point is the next fiber optic communication sampling time point; otherwise, it is moved to the next delayed sampling period.

[0119] Step 4: After the host has traversed all the sampling time points of the first delayed period, it starts the sampling time points of the next period and jumps back to Step 1.

[0120] This invention, by constructing an optical fiber loop topology for a multi-machine load system, obtains the total current of the multi-machine load frequency conversion sampling system and also implements a method for measuring the AC impedance of the multi-machine frequency conversion sampling system.

[0121] like Figure 9-10 As shown, when measuring AC impedance in a multi-machine load frequency conversion sampling system, two functional modules are added to the main load: a voltage sampling module and an impedance calculation module. The voltage sampling module is responsible for sampling the total voltage value of the multi-machine load system, and the impedance calculation module calculates the AC impedance by acquiring the instantaneous values ​​of current and voltage over multiple full cycles.

[0122] First, based on the method for measuring the total current of a multi-machine load frequency conversion sampling system described above, the host load is sampled according to a set sampling period, and the sum of the currents Sn of N loads in the multi-machine load system is obtained through the fiber optic loop topology.

[0123] Simultaneously, the newly added voltage sampling module on the host load also samples synchronously with the current module according to the set sampling period, that is, simultaneously sampling and acquiring a voltage sampling data U1 and a current sampling data I1. Each time the host load acquires a voltage sampling data, it waits to receive the system total current sampling data transmitted over the optical fiber. Specifically, the host load samples the voltage value U1 and the current value I1 for the first time, sends I1 into the optical fiber loop topology, and after a fixed optical fiber loop delay, the host load receives the first system total current Sn1, sending (U1, Sn1) as the first variable combination into the impedance calculation module. This process continues, with the host load obtaining a set of voltage and system total current sampling values ​​every sampling period Tsys, namely (U2, Sn2), (U3, Sn3), (U4, Sn4), ... (Uk, Snk).

[0124] The impedance calculation module continuously receives voltage and total system current samples. It processes the voltage and total current samples over multiple cycles to calculate the AC voltage amplitude Um and voltage phase φu, as well as the total current amplitude Im and total current phase φi, thereby obtaining the AC impedance.

[0125] The magnitude of the AC impedance is the ratio of the voltage amplitude to the current amplitude, i.e.

[0126] |Z|=Um / Im

[0127] The phase angle of the AC impedance is the phase difference between the voltage and the total current, i.e.

[0128] ΦZ=φu–φi

[0129] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A multi-computer variable frequency sampling system based on optical fiber, which is based on an optical fiber loop communication structure composed of a host computer and a plurality of slave computers, characterized in that, The host comprises a fiber communication module, a sampling module and a frequency conversion algorithm module, the frequency conversion algorithm module adjusts and delays the sampling time points according to the highest sampling frequency of the ADC and the sampling frequency set by the system, calculates the sampling time points according to the sampling frequency set by the system, calculates the difference between the sampling time points and the fiber communication sampling time points one by one, if the difference is greater than the sampling period corresponding to the highest sampling frequency of the ADC, the sampling time point is the next fiber communication sampling time point, otherwise, the sampling time point is delayed by one sampling period, and the process is repeated until all the sampling time points meet the condition, the fiber communication sampling time points are generated, and the received sampling values are recombined to restore the data sequence in the order of the delayed identifiers through high-speed fiber communication.

2. The multi-machine variable frequency sampling system based on optical fiber according to claim 1, wherein, In the fiber loop communication structure, any machine can be the host, and the others are slaves; or one channel module in one machine can be the host, and the other channel modules are slaves.

3. The multi-machine sampling system based on optical fiber according to claim 1, wherein, The host and the plurality of slaves are each provided with a current sampling module.

4. A multi-machine frequency conversion sampling method based on an optical fiber, based on the multi-machine frequency conversion sampling system based on an optical fiber in any one of claims 1 to 3, characterized in that, when the required sampling frequency of the system is less than the highest sampling frequency of the ADC, the system controls the host to initiate the interval time of a new communication frame, so as to set the sampling frequency of the system current measurement; when the required sampling frequency of the system is greater than the highest sampling frequency of the ADC, the multi-machine frequency conversion sampling is implemented as follows: Step one, the host first calculates the sampling time points of the current signal within more than one period and less than two periods according to the required sampling frequency of the system, and adds the delay identifier of each sampling time point; Step two, define the time point when the host initiates the first frame of communication frame as the latest fiber communication frame initiation time point, the host reads the first sampling period sampling time point in turn, calculates the difference between the time point and the latest fiber communication frame initiation time point every time a value is read, if the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC ADC , then the time point is the next fiber communication sampling time point, otherwise, move to the next delayed sampling period; Step three, when the host traverses all sampling time points of the first current cycle, the next cycle sampling time point is started, and whether the next cycle is a new sampling cycle or a delayed sampling cycle is obtained by judging the delay identifier. The first delayed sampling cycle sampling time point is read in turn, the difference between the time point and the latest optical fiber communication frame initiation time point is calculated for each read value, and if the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC ADC , the time point is the next optical fiber communication sampling time point, otherwise, the next delayed sampling cycle is moved in. Step four, after the host traverses all the sampling time points of the first delay period, the next period sampling time point is started, and the process returns to step one.

5. The method of claim 4, wherein the sampling is performed by a plurality of frequency converters. The host starts a new current sampling, the receiving module empties the sampling data buffer, waits for the first current sampling value and the delay identifier bit is 0, the host enters the current sampling value receiving, and after receiving a current sampling value, the current sampling value is stored in the buffer module, the delay identifier bit is read, and the address is recorded, after the current sampling value receiving is completed, the current sampling value recombination is entered, and one current sampling value is read at each address in turn, and a new current sampling value sequence is recombined.

6. The method of claim 4, wherein the sampling is performed by a plurality of frequency converters. The slave receives the current value transmitted by the host through the optical fiber receiving end in the fiber communication module, adds the real-time current value collected by the local current sampling module, and sends the added value to the next slave through the optical fiber sending end, and the host receives the current total value of the N machines through the optical fiber receiving end after passing through the fiber loop, and completes the current measurement of the multi-machine.

7. The method of claim 4, wherein the sampling is performed by a plurality of frequency converters. The application also comprises a voltage sampling module and an impedance calculation module, wherein the voltage sampling module is used for sampling the total voltage value of the multi-machine system, the impedance calculation module calculates the AC impedance by obtaining the current and voltage instantaneous values of multiple complete periods, the voltage sampling module and the current sampling module of the host machine are synchronously sampled according to the set sampling period, the voltage sampling data and the total current sampling data are synchronously input into the impedance calculation module, the impedance calculation module obtains the voltage value and the total current value of multiple complete periods, respectively calculates the voltage amplitude and phase and the total current amplitude and phase, and obtains the AC impedance.

8. A method for multi-machine frequency sampling based on optical fiber, based on the multi-machine frequency sampling system based on optical fiber in claim 1, characterized in that, The host machine and the multiple slave machines are each provided with a voltage sampling module; When the required sampling frequency of the system is less than the highest sampling frequency of the ADC, the system controls the host machine to initiate the interval time of a new communication frame, so as to set the sampling frequency of the system voltage measurement; When the required sampling frequency of the system is greater than the highest sampling frequency of the ADC, the multi-machine variable frequency sampling is implemented as follows: Step one, the host machine firstly calculates the sampling time points within one period and less than two periods of the voltage signal according to the required sampling frequency of the system, and simultaneously attaches the delay identifier of each sampling time point; Step two, define the time point when the host initiates the first frame of communication frame as the latest fiber communication frame initiation time point, the host reads the first sampling period sampling time point in turn, calculates the difference between the time point and the latest fiber communication frame initiation time point every time a value is read, if the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC ADC , then the time point is the next fiber communication sampling time point, otherwise, move to the next delayed sampling period; Step three, when the host traverses all sampling time points of the first voltage period, the next period sampling time point is started, and it is obtained through judging the delay identifier that the next period is a new sampling period or a delay sampling period. The first delay sampling period sampling time point is read in turn, the difference between the time point and the latest optical fiber communication frame initiation time point is calculated for each read value, and if the difference is greater than the minimum sampling period T corresponding to the highest sampling frequency of the ADC ADC , the time point is the next optical fiber communication sampling time point, otherwise, the next delay sampling period is moved in. Step four, after the host machine traverses all the sampling time points of the first delay period, the next period sampling time point is started, and the process is returned to step one.

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