CN205861836U - The voltage dip synchronous monitoring system of multistage power grid - Google Patents

Abstract

The utility model discloses a voltage sag synchronous monitoring system for a multi-level power grid, which comprises a voltage sag synchronous monitoring device arranged at each voltage level bus node of each outlet circuit and a synchronous monitoring device with each voltage sag The upper computer connected by communication, the voltage sag synchronous monitoring device includes a signal acquisition module electrically connected to the three first current transformers in the voltage and current acquisition cabinet and three voltage transformers, and the signal acquisition module A signal processor electrically connected, a GPS clock module electrically connected with the signal processor, and a first communication module used for communication connection with an upper computer. The voltage sag synchronous monitoring system of the above-mentioned multi-level power grid can monitor the power quality information of each voltage level bus node in real time and upload it to the host computer in real time. When a voltage sag occurs, the signal can be transmitted to the host computer in real time, which is convenient The upper computer performs subsequent analysis and evaluation.

Description

Synchronous monitoring system for voltage sag in multi-level power grid

technical field

The utility model relates to the field of power quality monitoring, in particular to a voltage sag synchronous monitoring system of a multi-level power grid.

Background technique

With the construction of smart grid, the system capacity, scale, voltage level and other rapid development, the complexity and diversity of the system, user productivity and equipment sensitivity increase. Fundamental changes have taken place in the load structure and electrical characteristics, especially renewable energy power generation systems, user equipment and industrial processes based on microelectronics, computers, power electronics and other technologies are increasingly connected to the power grid, and these devices have great influence on the voltage Sags are very sensitive, making voltage sags the most serious power quality problem. On the other hand, even faults of hundreds of kilometers may cause local voltage sags, and the frequency of voltage sags is much higher than other power quality problems. Among the complaints, more than 70% were caused by voltage sags. Therefore, a synchronous voltage sag monitoring system with modular structure design, high precision data acquisition and calculation, and multiple communication methods is designed to analyze and evaluate voltage sags, discover the law of voltage sag transfer, and prevent voltage sags caused by voltage sags. Major accidents are of great significance.

The evaluation and control of voltage sags are inseparable from the monitoring of power quality. At present, well-known foreign power quality companies such as LEM in Switzerland, UNIPOWER in Sweden, FLUKE in the United States, and domestic Shanghai Baosteel Anda Power Quality Co., Ltd. , Guodian Zhongke Electric Co., Ltd., etc., the research and development of power quality monitoring systems are relatively mature, and the functions are relatively complete. However, various power quality monitoring products on the market have the following limitations in the monitoring of voltage sags: 1) It mainly focuses on steady-state power quality indicators, and monitoring systems designed for dynamic power quality voltage sags are extremely rare; 2) Due to the transitivity of voltage sags, synchronous monitoring of each node is required, and the monitoring time accuracy of products on the market Low, and cannot meet the analysis and evaluation requirements. 3) There is no targeted evaluation system for the data processing of multi-level grid voltage sag monitoring; 4) The single means of communication is not conducive to the systematization of grid monitoring at all levels.

Therefore, although multifunctional power quality automatic monitoring products have been developed at home and abroad, there is no synchronous monitoring for voltage sags in multi-level power grids. For voltage sags, which has become the most serious power quality problem, it is necessary to establish Synchronous monitoring system for voltage sags in multi-level grids.

Utility model content

Aiming at the deficiencies of the prior art above, the technical problem to be solved by the utility model is: to provide a multi-level grid voltage sag synchronous monitoring system capable of realizing multi-level grid voltage sag synchronous monitoring.

In order to solve the above technical problems, the technical solution adopted by the utility model is to provide a synchronous monitoring system for voltage sags of multi-level power grids, including synchronous monitoring of voltage sags at each voltage level bus node of each outlet circuit device and an upper computer connected in communication with each voltage sag synchronous monitoring device, the voltage sag synchronous monitoring device includes three first current transformers on the bus and the secondary sides of the three voltage transformers are electrically connected A signal acquisition module electrically connected to the signal acquisition module, a signal processor electrically connected to the signal acquisition module, a GPS clock module electrically connected to the signal processor, and a first communication module for communicating with an upper computer.

As an optimization, the signal acquisition module includes a voltage-current transmission module electrically connected to the secondary sides of the three voltage transformers and the three first current transformers, and a voltage-current transmission module electrically connected to the voltage-current transmission module. A signal conditioning module, an A/D conversion module electrically connected to the signal conditioning module, and a phase-locked loop electrically connected to both the A/D conversion module and the signal conditioning module.

As an optimization, the voltage and current transmission module includes three voltage transmission circuits electrically connected to the secondary sides of the three voltage transformers in one-to-one correspondence and connected to the secondary sides of the three first current transformers one by one. One corresponds to three current transmission circuits electrically connected;

Each voltage transmission circuit includes first to eighth resistors and a first capacitor, the first end of the first resistor is electrically connected to the corresponding voltage transformer, and the second end passes through the second resistor, the third resistor and the fourth resistor in turn. The first capacitor is connected to the fourth resistor in parallel, and the node between the first capacitor and the fourth resistor is electrically connected to the signal conditioning module; the second resistor is connected to the fourth resistor The node between the three resistors is also connected to the node between the third resistor and the fourth resistor through the fifth resistor, the sixth resistor, the seventh resistor and the eighth resistor in sequence;

Each current transmission circuit includes a second current transformer, a ninth resistor, and a tenth resistor. The current transmission circuit passes through the primary side of the second current transformer and the secondary side of the corresponding first current transformer. Electrically connected, the secondary side of the second current transformer has two pins, the first pin is electrically connected to the signal conditioning module, and is grounded after passing through the ninth resistor and the tenth resistor in turn, and the first pin is electrically connected to the signal conditioning module. Two pins are connected directly to ground.

As an optimization, the signal conditioning module includes six signal conditioning circuits corresponding to three voltage transmission circuits and three current transmission circuits, and each signal conditioning circuit includes operational amplifiers, eleventh to fourteenth resistor and a second capacitor, the non-inverting input terminal of the operational amplifier is connected to the corresponding transmission circuit through the eleventh resistor, the inverting input terminal of the operational amplifier is grounded through the twelfth resistor, and directly through the tenth resistor The three resistors are directly connected to the output terminal, and the output terminal is grounded sequentially through the fourteenth resistor and the second capacitor, and the node between the fourteenth resistor and the second capacitor is electrically connected to the A/D conversion module.

As an optimization, the phase-locked loop adopts a general-purpose integrated phase-locked loop, model CD4046.

As an optimization, the host computer has a second communication module communicatively connected with the first communication module.

The voltage sag synchronous monitoring system of the multi-level power grid of the present invention is equipped with a voltage sag synchronous monitoring device at each voltage level bus node, and each voltage sag synchronous monitoring device is connected to the upper computer through communication , the voltage sag synchronous monitoring device is used to monitor the power quality information of each level of nodes in real time, and upload it to the host computer in real time. When a voltage sag occurs, the signal can be transmitted to the host computer in real time, which is convenient for the host computer to perform subsequent analysis evaluation. Each voltage sag synchronous monitoring device is equipped with a GPS clock module, which can effectively ensure that the monitoring devices at each voltage level have extremely high time accuracy in monitoring the start and end moments of the voltage sag, and its time accuracy can reach microseconds. The relative time accuracy of each monitoring device for synchronous monitoring of the same voltage sag source can reach within 10 microseconds.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a structural schematic diagram of an embodiment of a voltage sag synchronous monitoring system for a multi-level power grid of the present invention.

Fig. 2 is a block diagram of a voltage sag synchronous monitoring device in the voltage sag synchronous monitoring system of the multi-level power grid of the present invention.

FIG. 3 is a schematic circuit diagram of one of the voltage transmission circuits in the voltage and current transmission module in FIG. 2 .

FIG. 4 is a schematic circuit diagram of one of the current transmission circuits in the voltage and current transmission module in FIG. 2 .

FIG. 5 is a schematic circuit diagram of one of the signal conditioning circuits in the signal conditioning module in FIG. 2 .

FIG. 6 is a circuit diagram of the A/D conversion module in FIG. 2 .

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. example. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

Please refer to Fig. 1 to Fig. 6, the voltage sag synchronous monitoring system of the multilevel power grid of the present invention includes the voltage sag synchronous monitoring device (in this example, several The voltage sag synchronous monitoring device is installed one by one in the voltage and current acquisition cabinet at the bus node of each voltage level. The upper computer of the above-mentioned voltage sag synchronous monitoring device includes a signal acquisition module electrically connected to the secondary sides of three first current transformers and three voltage transformers on the bus, and a signal acquisition module electrically connected to the signal acquisition module A signal processor, a GPS clock module electrically connected to the signal processor, and a first communication module used for communication connection with an upper computer.

The voltage sag synchronous monitoring device is installed in the measurement cabinet corresponding to each bus node of the multi-level power grid (each bus node is equipped with a voltage and current measurement cabinet), and receives the secondary side signal of each real-time acquisition bus voltage transformer and the first The secondary side signal of the current transformer and the system time of each device are calibrated by a unified GPS clock signal. Specifically, there are three voltage transformers and three first current transformers on one bus, and each voltage sag synchronous monitoring device is connected with six transformers (three voltage transformers and three first current transformers) corresponding to the bus. Transformer) are electrically connected to the secondary side. The voltage sag synchronous monitoring transmits the collected and calculated electric energy parameters to the software of the upper computer in real time through various communication networks, and can realize the local display of each electric parameter.

Specifically, the signal acquisition module in this embodiment includes a voltage and current transmission module electrically connected to six transformers, a signal conditioning module electrically connected to the voltage and current transmission module, and a signal conditioning module electrically connected to the signal conditioning module. A connected A/D conversion module and a phase-locked loop electrically connected to the A/D conversion module and the signal conditioning module. The signal acquisition module simultaneously acquires A, B, C three-phase currents and A, B, C phase voltages.

The comprehensive function of the voltage and current transmission module and the signal conditioning module is to convert the voltage and current signals into voltage signals suitable for A/D sampling; the function of the A/D conversion module is to convert analog signals into digital signals, and the function of the phase-locked loop is Realize the automatic control of phase synchronization, and ensure that the A/D conversion chip can collect data according to the actual frequency of the power grid. in:

The voltage and current transmission module includes three voltage transmission circuits electrically connected to the three voltage transformers in one-to-one correspondence and three current transmission circuits electrically connected to the three first current transformers in one-to-one correspondence circuit. The three voltage transmission circuits have the same structure, the input terminals are respectively electrically connected to the three voltage transformers, and the output terminals are electrically connected to the signal conditioning module. Similarly, the circuit structures of the three current transmitters are the same, their input terminals are respectively electrically connected to the three first current transformers, and their output terminals are electrically connected to the signal conditioning module. The structure of one of the voltage transmission circuits and one of the current transmission circuits will be described in detail below.

See Figure 3 for details. The voltage transmission circuit includes first to eighth resistors and a first capacitor C8. The first end of the first resistor R3 is electrically connected to the corresponding voltage transformer, and the second end passes through the second resistor R4 in turn. , the third resistor 45 and the fourth resistor R12 are then grounded, the first capacitor C8 is connected in parallel with the fourth resistor R12, and the node between the first capacitor C8 and the fourth resistor R12 is connected to the signal conditioning The modules are electrically connected; the node between the second resistor R4 and the third resistor R5 passes through the fifth resistor R10, the sixth resistor R14, the seventh resistor R16 and the eighth resistor R17 in turn, and then connects with the third resistor R5 is connected to a node between the fourth resistor R12.

Please refer to FIG. 4 for details. The current transmission circuit includes a second current transformer CT1, a ninth resistor R39, and a tenth resistor R44. The current transmission circuit communicates with the corresponding first current through the second current transformer. The secondary side of the transformer is electrically connected, the second current transformer has two pins, the first pin is electrically connected to the signal conditioning module, and is also sequentially passed through the ninth resistor R39 and the tenth resistor R44 After ground, the second pin is directly connected to ground.

The signal conditioning module includes six signal conditioning circuits corresponding to three voltage transmission circuits and three current transmission circuits. The structure of the six signal conditioning circuits is the same, the only difference is that each signal conditioning circuit is electrically connected to a corresponding transmission circuit (voltage transmission circuit or current transmission circuit). The following describes one of the signal conditioning circuits as an example:

The signal conditioning circuit includes an operational amplifier U3B, eleventh to fourteenth resistors and a second capacitor C28, the non-inverting input terminal of the operational amplifier U3B is connected to the corresponding transmission circuit through the eleventh resistor R58, and directly connected to the 5V power supply, the inverting input terminal of the operational amplifier U3B is grounded through the twelfth resistor R60, the inverting input terminal is also directly connected to the -5V power supply, and directly connected to the output terminal through the thirteenth resistor R61, The output end is also grounded sequentially through the fourteenth resistor R59 and the second capacitor C28, and the node between the fourteenth resistor R59 and the second capacitor C28 is electrically connected to the A/D conversion module.

The A/D conversion module adopts the chip of model AD7606BSTZ-6. A/D sampling is the core circuit of the signal acquisition module. The signal processing module performs calculation and processing. In this embodiment, a 6-channel synchronous sampling chip AD7606BSTZ-6 is used to simultaneously collect three-phase currents of A, B, and C and voltages of phases A, B, and C. AD7606BSTZ-6 has built-in analog input clamp protection, second-order anti-aliasing filter, track-and-hold amplifier, 16-bit charge redistribution successive approximation ADC, flexible digital filter, 2.5V reference voltage source, reference voltage buffer and high-speed Serial and parallel second current transformers. Operating from a single 5-V supply, the AD7606BSTZ-6 can handle ±10-V and ±5-V true bipolar input signals while sampling at throughput rates up to 200 kSPS on all channels. The input clamp protection circuit can withstand voltages up to ±16.5V. The analog input impedance of the AD7606 is 1MΩ regardless of the sampling frequency. It operates from a single supply with on-chip filtering and high input impedance.

The phase-locked loop adopts the universal integrated phase-locked loop CD4046, which is a multifunctional single-chip integrated phase-locked loop composed of CMOS circuits, and has the advantages of low power consumption, high input impedance, and wide power supply voltage range. widely used in digital systems. The CD4046 phase-locked loop uses an RC type voltage-controlled oscillator, which must be connected with capacitors and resistors as charging and discharging components. There is a linear amplifier and a shaping circuit inside the CD4046, which can convert the input weak signal of about 100Mmv into a square wave or pulse signal.

The signal processor includes a DSP digital signal processing module electrically connected to the A/D conversion module and an ARM engineering module electrically connected to the DSP digital signal processing module. in:

In the present embodiment, what described digital signal processing module adopts is the STM32F429 type chip with DSP core, mainly as the platform of calculating every power quality parameter, it has the ARM 32 bit Cortex-M4 CPU of FPU, in Flash memory The self-adaptive real-time accelerator that realizes zero-wait-state operation performance, the main frequency is up to 180MHz MPU, and the performance up to 225DMIPS/1.25DMIPS/MHz can be achieved, and it has a DSP instruction set.

The ARM engineering module uses an LPC1788FBD208 chip, which mainly implements storage, management and display of power quality parameter results. LPC1788 is an ARM Cortex-M3 microcontroller integrated with an LCD image controller. It is a highly integrated microcontroller designed by NXP Semiconductors for various advanced communications, high-quality image display and other applications, with Cortex-M3 as the core. Controller, the microcontroller includes LCD controller, 10/100 Ethernet EMAC, USB full-speed Device/Host/OTG controller, CAN bus controller, SPI, SSP, IIC, IIS and external storage controller EMC, etc. resource.

GPS clock module: connected to the DSP data processing module to calibrate the system time of monitoring devices under different voltage levels with a unified GPS clock signal. When a short-circuit fault occurs at a point in the multi-level power grid, the GPS clock signal can effectively ensure that each voltage The monitoring devices under the level have extremely high time accuracy for monitoring the start and end moments of the voltage sag, and the time accuracy can reach microseconds, so that the relative time accuracy of each monitoring device for the synchronous monitoring of the same voltage sag source can reach 10 microseconds within seconds.

In this embodiment, the voltage sag synchronous monitoring device further includes an LCD liquid crystal display screen electrically connected to the signal processor for displaying query and setting on the spot. Query functions include basic power parameters, voltage quality, voltage harmonics, real-time curve and historical curve query, voltage sag event recording and analysis query. Setting function: system setting, which can be set according to the actual site conditions and so on.

The voltage sag synchronous monitoring system of the multi-level power grid of the present invention is equipped with a voltage sag synchronous monitoring device at each level of bus node, and each voltage sag synchronous monitoring device is connected to the host computer through communication, The voltage sag synchronous monitoring device is used to monitor the power quality information of each level of nodes in real time and upload it to the host computer in real time. When a voltage sag occurs, the signal can be transmitted to the host computer in real time, which is convenient for the host computer to carry out subsequent Analytical evaluation. Each voltage sag synchronous monitoring device is equipped with a GPS clock module, which can effectively ensure that the monitoring devices at each voltage level have extremely high time accuracy in monitoring the start and end moments of the voltage sag, and its time accuracy can reach microseconds. The relative time accuracy of each monitoring device for synchronous monitoring of the same voltage sag source can reach within 10 microseconds.

The above are only embodiments of the present utility model, and are not intended to limit the patent scope of the present utility model. Any equivalent structure or equivalent process conversion made by using the description of the utility model and the contents of the accompanying drawings, or directly or indirectly used in other related Technical fields are all included in the scope of patent protection of the utility model in the same way.

Claims (6)

1. the voltage dip synchronous monitoring system of a multistage power grid, it is characterised in that: include being located at the every of each transmission line circuit Voltage dip synchronous monitoring device at one electric pressure bus nodes and leading to each voltage dip synchronous monitoring device The host computer that news connect, described voltage dip synchronous monitoring device includes and three the first current transformers on bus and three The letter that the signal acquisition module of the electrical connection that the secondary side of voltage transformer all electrically connects electrically connects with described signal acquisition module Number gps clock module that processor electrically connects with described signal processor and for the first communication being connected with upper machine communication Module.

2. the voltage dip synchronous monitoring system of multistage power grid as claimed in claim 1, it is characterised in that: described signals collecting Module includes that the voltage x current all electrically connected with the secondary side of described three voltage transformers and three the first current transformers becomes The Signal-regulated kinase sending module to electrically connect with described voltage x current transmitting module electrically connects with described Signal-regulated kinase A/D modular converter and the phaselocked loop all electrically connected with described A/D modular converter and Signal-regulated kinase.

3. the voltage dip synchronous monitoring system of multistage power grid as claimed in claim 2, it is characterised in that: described voltage x current Transmitting module include three voltage transmission circuit electrically connecting with the secondary side one_to_one corresponding of described three voltage transformers and Three the electric current transmission circuits electrically connected with described three the first Current Transformer Secondary side one_to_one corresponding；

Each voltage transmission circuit all includes the first to the 8th resistance and the first electric capacity, and the first end of the first resistance is with corresponding Voltage transformer electrical connection, the second end passes sequentially through ground connection after the second resistance, the 3rd resistance and the 4th resistance, described first electricity Hold and be connected with described 4th resistor coupled in parallel, and the node between the first electric capacity and described 4th resistance and described signal condition mould Block electrically connects；Node between described second resistance and described 3rd resistance also pass sequentially through the 5th resistance, the 6th resistance, the 7th It is connected with the node between described 3rd resistance and the 4th resistance after resistance and the 8th resistance；

Each electric current transmission circuit all includes one second current transformer, the 9th resistance, the tenth resistance, described electric current transmission circuit Being electrically connected with the first corresponding Current Transformer Secondary side by the primary side of this second current transformer, described second electric current is mutual The secondary side of sensor has two pins, and first pin electrically connects with described Signal-regulated kinase, also passes sequentially through described Ground connection after nine resistance and the tenth resistance, second pin is directly grounded.

4. the voltage dip synchronous monitoring system of multistage power grid as claimed in claim 3, it is characterised in that: described signal condition Module includes and three voltage transmission circuit and three electric current transmission circuits six signal conditioning circuits, Mei Yixin one to one Number modulate circuit all includes operational amplifier, the 11st to the 14th resistance and the second electric capacity, described operational amplifier same Phase input is connected with corresponding transmission circuit by described 11st resistance, and the inverting input of described operational amplifier passes through 12nd resistance eutral grounding, is also directly joined directly together with outfan by the 13rd resistance, and described outfan also passes sequentially through the tenth Four resistance and the second capacity earth, the node between described 14th resistance and the second electric capacity is electrically connected with described A/D modular converter Connect.

5. the voltage dip synchronous monitoring system of multistage power grid as claimed in claim 2, it is characterised in that: described phaselocked loop is adopted Using general integrated phase lock, model is CD4046.

6. the voltage dip synchronous monitoring system of the multistage power grid as described in claim any one of claim 1 to 5, it is special Levy and be: described host computer has the second communication module being connected with described first communication module communication.