CN101893668B - Three-phase three-wire and three-phase four-wire compatible electrical parameter signal measurement and process system - Google Patents

Abstract

The invention relates to a three-phase three-wire and three-phase four-wire compatible electrical parameter signal measurement and processing system, which is characterized in that the system consists of a voltage connection terminal, a current connection terminal, a connection mode switching switch, a voltage dividing resistor, a signal processing circuit and a microcontroller MCU Composition: The signal processing circuit is composed of voltage transformers, voltage channel filters, current transformers, current channel filters and single-phase electrical parameter measurement chips connected in series. There are 3 sets of independent signal processing circuits in this device. The voltage terminals are externally connected to the grid and internally connected to the voltage transformer; the external connection mode of the current terminal is connected to the phase line of the grid in series, and the internal connection is connected to the current transformer in sequence; the voltage terminal and the current terminal are internally connected to each other according to their respective paths. The signal processing circuit reads the parameter values of each circuit to the microcontroller, and calculates the three-phase electrical parameters. Adopting the technical solution of the invention can reduce manufacturing cost, simplify production storage and sales management, and facilitate users to purchase and select models.

Description

Three-phase three-wire and three-phase four-wire compatible electrical parameter signal measurement and processing system

technical field

The invention relates to an electrical parameter signal measurement and processing system, in particular to a three-phase three-wire and three-phase four-wire compatible three-phase electrical parameter signal measurement and processing system.

Background technique

Three-phase AC parameter measuring instruments are divided into two types: three-phase three-wire system and three-phase four-wire system. The wiring methods and signal processing methods of these two types of instruments are different, so they need to be clearly distinguished during design, production and use. The two are not compatible and must be sold or purchased separately, kept separately, and used separately The management of production, sales and use brings a lot of inconvenience.

In the signal processing technology of three-phase AC parameter measurement, the typical technical solution is to use special chips for three-phase electrical parameter measurement such as ADE7758, ATT7026A and ATT7022A as the core signal processing devices, but these chips are expensive and account for the total number of devices. a larger proportion of the cost.

Contents of the invention

The purpose of the present invention is to propose a signal processing system scheme for measuring three-phase electrical parameters using a low-cost single-phase electrical parameter measurement chip to overcome the above-mentioned shortcomings. The system can be compatible with three-phase three-wire systems and three-phase four-wire systems A wiring method. Adoption of the technical scheme of the invention can greatly reduce the manufacturing cost, simplify the management of production storage and sales, and facilitate the purchase and selection of users.

The technical solution adopted to achieve the above purpose is: a compatible three-phase electrical parameter signal measurement and processing system, which is composed of a voltage terminal, a current terminal, a connection mode switch, a voltage dividing resistor, a signal processing circuit and a microcontroller MCU; The voltage terminal is externally connected to the power grid, and the internal connection method is to switch the switch through the parallel connection of the voltage dividing resistor and then connect to the voltage transformer, voltage channel filter, and single-phase electrical parameter measurement chip; the external connection method of the current terminal is to press the pair It is connected in series with the phase line of the power grid, and the internal connection is sequentially connected to the current transformer, current channel filter, and single-phase electrical parameter measurement chip; the voltage terminal and the current terminal are internally connected to the signal processing circuit according to their respective paths, and the signal processing circuit The measured parameter values are read to the microcontroller MCU, and then comprehensive calculation is performed according to the mathematical relationship determined by the three-phase three-wire or three-phase four-wire connection mode, and the three-phase electrical parameters are calculated.

There are 4 voltage terminals, which are UA, UB, UC and UN. UA, UB and UC are respectively externally connected to the three phase lines A, B and C of the power grid or A, Phase B and C phase terminals, UN is connected to the neutral wire of the three-phase four-wire system, or connected to the three-phase three-wire system UB.

There are 6 current terminals, two pairs, specifically IA/IAR, IB/IBR, IC/ICR, and IA/IAR is used to connect the A-phase line of the power grid in series or connect the current mutual inductance on the A-phase line outside the instrument. IB/IBR is used to connect in series to the B-phase line of the power grid or to the secondary side of the current transformer connected to the B-phase line outside the instrument. IC/ICR is used to connect in series to the C-phase line of the power grid or Connect to the secondary terminal of the current transformer on the C-phase line outside the meter.

The signal processing circuit is composed of voltage transformers, voltage channel filters, current transformers, current channel filters and single-phase electrical parameter measurement chips connected in series. There are 3 sets of independent signal processing circuits in this system, of which : The voltage transformer is a two-port network, its secondary side is connected to the voltage channel filter as the input of the voltage channel filter, and the output of the voltage channel filter is connected to the voltage channel input terminal of the single-phase electrical parameter measurement chip; the current transformer It is a two-port network, the primary side is connected to the current terminal IA/IAN, IB/IBN, IC/ICN of each phase according to the signal processing circuit, and the secondary side is connected to the current channel filter as the input of the current channel filter; the current The output of the channel filter is connected to the current channel input terminal of the single-phase electrical parameter measurement chip; one end of the voltage dividing resistor RA is connected to the voltage terminal UA, and the other end is connected to the upper end of the primary side of the voltage transformer 1A; the voltage dividing resistor RB One end of the connection mode switching switch is connected to the terminal X, and the other end is connected to the upper end of the primary side of the voltage transformer 1B; one end of the voltage dividing resistor RC is connected to the voltage terminal UC, and the other end is connected to the primary side of the voltage transformer 1C the upper connection. Dividing the measured voltage by using a voltage dividing resistor, so that the voltage applied to the primary side of the voltage transformer is attenuated so that the voltage channel filter and the single-phase electrical parameter measurement chip can perform signal processing;

The wiring mode changeover switch is a double-pole double-throw toggle switch with 6 terminals of SA, SB, SC, SN, X and Y, the terminal SA is connected to the voltage terminal UA; the terminal SB is connected to the voltage terminal The connecting terminal UB is connected; the connecting terminal SC is connected with the voltage connecting terminal UC; the connecting terminal SN is connected with the voltage connecting terminal UN, and also connected with the lower end of the primary side of the voltage transformer 1A and the lower end of the primary side of the voltage transformer 1C; the connecting terminal X is connected to the voltage dividing resistor RB; the terminal Y is connected to the lower end of the primary side of the voltage transformer 1B. When the wiring mode switching switch is turned upwards, terminal X is closed and conducted with terminal SA, and disconnected with terminal SB, terminal Y is closed and conducted with terminal SC, and disconnected with terminal SN. When the switch is turned downwards , the connection terminal X is closed and conducted with the connection terminal SB, and disconnected with the connection terminal SA, and the connection terminal Y is closed and conducted with the connection terminal SN, and disconnected with the connection terminal SC.

The single-phase electrical parameter measurement chip has a single-phase electrical parameter measurement function, and can measure the current effective value, voltage effective value, current instantaneous value, and voltage instantaneous value of single-phase AC, and can accumulate active electric energy in a short period of time , and these parameter values can be sent to the microcontroller MCU through serial communication;

The logical connection between the above three sets of signal processing circuits is: read the measurement parameter values of the three single-phase electrical parameter measurement chips to the microcontroller MCU respectively, and then determine according to the three-phase three-wire or three-phase four-wire connection mode The mathematical relationship is comprehensively processed, and the three-phase electrical parameters are calculated.

The present invention has the following beneficial effects: three single-phase electrical parameter measurement chips can be used to realize signal processing for three-phase AC parameter measurement, and electrical parameters such as line current, line voltage, phase voltage, and active power can be measured and calculated for phase separation and phase combination , reactive power, apparent power, power factor, frequency, zero-sequence current, active energy, reactive energy, etc., the use of the wiring mode switch can realize the three-phase three-wire system and three-phase four-wire system wiring mode Signal processing for electrical parameter measurements.

Description of drawings

Figure 1 is a module structure diagram of a compatible three-phase electrical parameter signal measurement and processing system

Fig. 2 is a circuit connection diagram of a compatible three-phase electrical parameter signal measurement and processing system.

In Figure 2, the dotted line box of 6 is the voltage terminal group, including 4 voltage terminals UA, UB, UC and UN. In the case of three-phase four-wire system, connect the three phases A, B and C of the power grid with connecting wires. line and grid neutral line; when the three-phase three-wire system has no neutral line, connect UN to UB with connecting wires, and connect UA, UB, and UC to the three phase wires A, B, and C of the grid with connecting wires; the dotted line of 7 Inside the frame is the current terminal group, including 6 current terminal terminals IA/IAR, IB/IBR, IC/ICR in three pairs. IA/IAR is used to connect the A phase line of the power grid in series or connect the A phase line outside the instrument. The secondary side terminal of the current transformer, IB/IBR is used to connect the B phase line of the grid in series or the secondary side terminal of the current transformer connected to the B phase line outside the instrument, and the IC/ICR is used to connect the grid C in series The phase line or the secondary side terminal of the current transformer connected to the C-phase line outside the instrument; the dotted line frame of 8 indicates the wiring mode switch, which is a double-pole double-throw toggle switch with 6 terminals, three-phase Turn the switch down for the four-wire system, and turn the switch up for the three-phase three-wire system; RA, RB, and RC are three voltage divider resistors, which are used to divide the measured voltage so that the voltage added to the primary side of the voltage transformer voltage decay. 9 is a microcontroller.

Detailed ways

The technical scheme of the present invention is further described in conjunction with Fig. 2 below, a kind of compatible three-phase electrical parameter signal measurement and processing system, consists of voltage connection terminals UA, UB, UC and UN, three pairs of current connection terminals IA/IAR, B/IBR and IC/ICR, terminals SA, SB, SC, SN, X and Y in the wiring mode changeover switch, 3 voltage transformers 1A, 1B and 1C, 3 voltage dividing resistors RA, RB and RC, 3 voltage channels Filters 2A, 2B, and 2C, 3 current transformers 5A, 5B, and 5C, 3 current channel filters 4A, 4B, and 4C, 3 single-phase electrical parameter measurement chips 3A, 3B, and 3C, 1 Microcontroller (9) is formed;

The voltage connection terminal group (6) contains 4 voltage connection terminals, namely UA, UB, UC and UN, and the current connection terminal group (7) contains 6 pieces to form 3 pairs of current connection terminals, namely IA/IAR, IB/IBR, IC /ICR, wiring mode changeover switch (8) is a double-pole double-throw toggle switch with 6 terminals, and its 6 terminals are SA, SB, SC, SN, X and Y, used for three-phase three-wire system When the switch is turned upwards, terminal X is closed and conducted with terminal SA, and disconnected with terminal SB, terminal Y is closed and conducted with terminal SC, and disconnected with terminal SN. Closed conduction with terminal SB, disconnected with terminal SA, closed conduction with terminal SN, disconnected with terminal SC;

For voltage transformers (1A, 1B, 1C), voltage channel filters (2A, 2B, 2C), current transformers (5A, 5B, 5C), current channel filters (4A, 4B, 4C), single-phase Parameter measurement chips (3A, 3B, 3C) have a total of 5 devices divided into 3 groups: A, B, and C. The last letter of the device identification in the same group is the same, that is, the devices identified as 1A, 2A, 3A, 4A, and 5A are A Group, devices marked as 1B, 2B, 3B, 4B, 5B are group B, devices marked as 1C, 2C, 3C, 4C, 5C are group C, and 5 devices in each group are interconnected to form 3 independent sets The signal processing circuits are A phase sequence signal processing circuit, B phase sequence signal processing circuit and C phase sequence signal processing circuit. The internal connection methods of the three sets of signal processing circuits are the same, and the internal connection methods are: voltage transformer (1A, The secondary side of 1B, 1C) is connected to the voltage channel filter (2A, 2B, 2C) as the input of the voltage channel filter (2A, 2B, 2C), and the output of the voltage channel filter (2A, 2B, 2C) is connected to To the input terminal of the voltage channel of the single-phase electrical parameter measurement chip (3A, 3B, 3C), the secondary side of the current transformer (5A, 5B, 5C) is connected to the current channel filter (4A, 4B, 4C) as the current channel The input of the filter (4A, 4B, 4C), the output of the current channel filter (4A, 4B, 4C) is connected to the current channel input terminal of the single-phase electrical parameter measurement chip (3A, 3B, 3C);

The primary sides of the three current transformers (5A, 5B, 5C) are respectively connected to the current terminals of each phase according to the phase sequence of the signal processing circuit, that is, the A phase sequence, the B phase sequence, and the C phase sequence, that is, the current transformers The primary side of (5A) is connected to current terminal IA/IAN, the primary side of current transformer (5B) is connected to current terminal IB/IBN, and the primary side of current transformer (5C) is connected to current terminal IC/ICN;

The upper end of the primary side of the A-phase sequence voltage transformer (1A) is connected to one end of the voltage dividing resistor RA, the other end of the voltage dividing resistor RA is connected to the voltage terminal UA, and the lower end of the primary side of the A-phase sequence voltage transformer (1A) is connected to Voltage terminal UN; the upper end of the primary side of the B-phase sequence voltage transformer (1B) is connected to one end of the voltage dividing resistor RB, and the other end of the voltage dividing resistor RB is connected to the terminal X of the wiring mode switch (8), and the B phase sequence voltage The lower end of the primary side of the transformer (1B) is connected to the terminal Y of the wiring mode changeover switch (8); the upper end of the primary side of the C-phase sequence voltage transformer (1C) is connected to one end of the voltage dividing resistor RC, and the other end of the voltage dividing resistor RC One end is connected to the voltage terminal UC, the lower end of the primary side of the C-phase sequence voltage transformer (1C) is connected to the voltage terminal UN; the terminal SA of the wiring mode changeover switch (8) is connected to the voltage terminal UA, and the wiring mode changeover switch (8) The terminal SB of the wiring mode selector switch (8) is connected to the voltage terminal UB, the terminal SC of the wiring mode switch (8) is connected to the voltage terminal UC, and the terminal SN of the wiring mode selector switch (8) is connected to the voltage terminal UN;

Three single-phase electrical parameter measurement chips (3A, 3B, 3C) have the single-phase electrical parameter measurement function, which can measure the current effective value, voltage effective value, current instantaneous value, and voltage instantaneous value of single-phase AC. The active electric energy is accumulated, and these parameter values can be sent to the microcontroller MCU (9) through serial communication;

The logical connection between the above three sets of signal processing circuits is: respectively read the measured parameter values of the three single-phase electrical parameter measurement chips (3A, 3B, 3C) to the microcontroller MCU (9), and then according to the three-phase three-wire Or the mathematical relationship determined by the three-phase four-wire connection method is processed comprehensively, and the three-phase electrical parameters are calculated.

The terms, symbols and examples used in the above technical solutions do not limit the application of the present invention, but are for convenience of description.

Claims (5)

1. phase three-wire three and three-phase and four-line compatible electrical parameter signal measurement and process system, system is sub by voltage terminal, current terminal, mode of connection change-over switch, divider resistance, signal processing circuit and microcontroller MCU form; Voltage terminal connects grid line outward, in connect mode for through being connected to voltage transformer (VT), voltage channel wave filter, single-phase electricity parameter measurement chip successively after the divider resistance parallel connection mode of connection change-over switch; Current terminal connects mode outward for by to being series at the electrical network phase line, in be linked as and be connected to current transformer, current channel wave filter, single-phase electricity parameter measurement chip successively; Voltage terminal and current terminal are by being connected to signal processing circuit in the path separately; The measured parameter value of signal processing circuit is read microcontroller MCU; Carry out comprehensive calculation process according to phase three-wire three or the determined mathematical relation of the three-phase and four-line mode of connection again; Calculate three phase electrical parameters, it is characterized in that:

Described voltage terminal has 4; Be UA, UB, UC and UN, UA, UB and UC are external in A, B, the C phase exit of the secondary side of electrical network A, B, three phase lines of C or instrument external voltage mutual inductor respectively; UN connects three-phase four-wire system electrical network center line, or connects three-phase three-wire system UB;

Described mode of connection change-over switch is a DPDT toggle switch with 6 connection terminals of SA, SB, SC, SN, X and Y; Its middle connecting terminal SA is connected with the sub-UA of voltage terminal; Connection terminal SB links to each other with the sub-UB of voltage terminal; Connection terminal SC is connected with the sub-UC of voltage terminal, and connection terminal SN is connected with the sub-UN of voltage terminal, also is connected with the lower end of the primary side of the lower end of the primary side of voltage transformer (VT) 1A and voltage transformer (VT) 1C; Connection terminal X is connected with divider resistance RB, and connection terminal Y is connected with the lower end of the primary side of voltage transformer (VT) 1B; When mode of connection change-over switch is upwards dialled; The closed conducting of connection terminal X and connection terminal SA, break off with connection terminal SB; The closed conducting of connection terminal Y and terminal SC, break off with connection terminal SN; When switch when setting aside, the closed conducting of connection terminal X and connection terminal SB, break off with connection terminal SA, connection terminal Y and the closed conducting of connection terminal SN, with connection terminal SC disconnection.

2. phase three-wire three according to claim 1 and three-phase and four-line compatible electrical parameter signal measurement and process system; It is characterized in that described current terminal has 6; Two a pair of; Be specially IA/IAR, IB/IBR, IC/ICR; IA/IAR be used to be connected in series electrical network A phase line or connect the secondary side exit of the current transformer on the outer A phase line of instrument, IB/IBR be used to be connected in series electrical network B phase line or connect the secondary side exit of the current transformer on the outer B phase line of instrument, IC/ICR be used to be connected in series electrical network C phase line or connect the secondary side exit of the current transformer on the outer C phase line of instrument.

3. phase three-wire three according to claim 1 and three-phase and four-line compatible electrical parameter signal measurement and process system; It is characterized in that described signal processing circuit; Contact successively by voltage transformer (VT), voltage channel wave filter, current transformer, current channel wave filter and single-phase electricity parameter measurement chip and to constitute; Have 3 cover separate signal treatment circuits in the native system; Wherein: voltage transformer (VT) is a two-port network, and its secondary side is connected to the input of voltage channel wave filter as the voltage channel wave filter, and the output of voltage channel wave filter is connected to the voltage channel input end of single-phase electricity parameter measurement chip; Current transformer is a two-port network, and its primary side is connected to each phase current connection terminal IA/IAN, IB/IBN, IC/ICN respectively by signal processing circuit, and secondary side is connected to the input of current channel wave filter as the current channel wave filter; The output of current channel wave filter is connected to the current channel input end of single-phase electricity parameter measurement chip; The end of divider resistance RA is connected with the sub-UA of voltage terminal, and the other end is connected with the upper end of the primary side of voltage transformer (VT) 1A; The end of divider resistance RB is connected with mode of connection change-over switch connection terminal X, the other end be connected with the upper end of the primary side of voltage transformer (VT) 1B; The end of divider resistance RC is connected with the sub-UC of voltage terminal, and the other end is connected with the upper end of the primary side of voltage transformer (VT) 1C.

4. phase three-wire three according to claim 1 and three-phase and four-line compatible electrical parameter signal measurement and process system; It is characterized in that described single-phase electricity parameter measurement chip; Has single-phase electricity parameter measurement function; Can measure current effective value, voltage effective value, current instantaneous value, the instantaneous voltage of single-phase AC, the active energy in the short time is accumulated, and these parameter values can be delivered to microcontroller MCU through serial communication mode.

5. phase three-wire three according to claim 3 and three-phase and four-line compatible electrical parameter signal measurement and process system; It is characterized in that the logical communication link between the described 3 cover signal processing circuits is: the measured parameter value of 3 single-phase electricity parameter measurement chips is read microcontroller MCU respectively; Carry out comprehensive calculation process according to phase three-wire three or the determined mathematical relation of the three-phase and four-line mode of connection again, calculate three phase electrical parameters.

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