CN107643437B - Complex ratio current transformer for on-line intelligent conversion - Google Patents

Abstract

The invention relates to a complex ratio current transformer in an electric energy metering device, a complex ratio current transformer, in particular to an on-line intelligent conversion complex ratio current transformer. The problem that the existing complex-ratio current transformer cannot be automatically converted online is solved. The complex ratio current transformer for online intelligent conversion includes the complex ratio current transformer body CT, the sampling current transformer CT1, the RMS processing circuit module, the A/D conversion module, the MCU microprocessor with the input port, and the control relay JK , Protection relay JB, size ratio shared power-off delay relay J2, large ratio power-off delay relay J1. The invention can realize on-line automatic switching of variable ratio, and has protection measures to prevent secondary open circuit; the structure design is reasonable and unique, solves the problem that the existing complex ratio current transformer cannot be automatically switched on-line, and can effectively avoid equipment damage and Personal injury accident. The present invention is suitable for electric energy metering device.

Description

Complex ratio current transformer for on-line intelligent conversion

technical field

The invention relates to a complex ratio current transformer in an electric energy metering device, a complex ratio current transformer, in particular to an on-line intelligent conversion complex ratio current transformer.

Background technique

At present, the circuit of the electric energy metering device only designs a current transformer with a single transformation ratio or a double transformation ratio for the rated load power. Because the secondary open circuit is very dangerous to the power grid. If the current transformer ratio needs to be replaced, the power must be cut off. It is very dangerous to manually short-circuit the jumper to replace the ratio, and the safety regulations are not allowed. The current transformers used for electric energy measurement are all of S grade, and are generally designed to operate within the range of 20% to 120% of the rated current of the transformation ratio. JJG1021-2007 "Power Transformer", the error limit of S-class current transformer in this range is linear and stable. When it exceeds the range of 20% to 120% of the rated current, the current transformer ratio error will increase. Sometimes the current exceeds several times to a hundred times the rated current, such as wind (water) power generation and electricity consumption, or heating and non-heating periods, or the seasonal electricity load of enterprises that start periodically. The variable ratio quantity limit varies from 5 times to 100 times, which is far beyond the measurable range of ordinary current transformers, resulting in leakage measurement and energy waste under low load or overload. Adding two sets of metering systems needs to increase the land space and metering equipment. In addition, there are contacts in the middle of the external ratio conversion controller line, which may lead to the possibility of electricity stealing, increase the difficulty of lead sealing, and increase the failure points and operation and maintenance costs. Does not meet the current national standard regulations.

Now some power management departments use compound double-ratio current transformers or multi-ratio current transformers. When the compound transformation ratio current transformers change the transformation ratio, a series of manual operations such as power failure and rewiring are required to supply electricity. It brings inconvenience and financial loss to customers, while requiring a lot of time and manpower.

SUMMARY OF THE INVENTION

The invention solves the problem that the existing complex ratio current transformer cannot be automatically converted online, and provides a complex ratio current transformer capable of on-line intelligent conversion.

The present invention is realized by adopting the following technical scheme: a complex ratio current transformer for online intelligent conversion, including a complex ratio current transformer body CT, a sampling current transformer CT1, an RMS processing circuit module, an A/D conversion module, a communication interface MCU microprocessor, protection relay JB, control relay JK, size ratio shared power-off delay relay J2, large ratio power-off delay relay J1; any secondary winding of the complex ratio current transformer body CT is selected as The metering secondary winding has a common tap end 1S1, a small change ratio tap end 1S2 and a large change ratio tap end 1S3; the common tap end 1S1 is coupled with the primary winding of the sampling current transformer CT1 as the measurement secondary winding. Polarity terminal; the small ratio tap end 1S2 is connected to one end of the normally open contact J2-1 of the power-off delay relay J2 shared by the size ratio, and the normally open contact J2- of the power-off delay relay J2 shared by the size ratio The other end of 1 is used as the common non-polar terminal 1COM of the measuring secondary winding; the tap terminal 1S3 of the large transformation ratio shares one end of the normally closed contact J2-2 of the power-off delay relay J2 with the large transformation ratio at the same time, and the large transformation ratio is turned off. One end of the normally open contact J1-1 of the electric delay relay J1 is connected to one end of the normally closed contact JB-1 of the protection relay JB, and the size ratio is shared with the other end of the normally closed contact J2-2 of the power-off delay relay J2. One end, the other end of the normally open contact J1-1 of the large ratio power-off delay relay J1 and the other end of the normally closed contact JB-1 of the protection relay JB are all connected to the common non-polar terminal 1COM; sampling current mutual inductance Both ends of the secondary winding of the CT1 are connected with a sampling resistor R, one end of the sampling resistor R is grounded, and the other end is connected to the input of the RMS processing circuit module, the output of the RMS processing circuit module is connected to the input of the A/D conversion module, A The output of the /D conversion module is connected with the input of the MCU microprocessor. The output terminal of the MCU microprocessor controls the electrification and de-energization of the control relay JK. In the power supply circuit of the time relay J2, the normally closed contact of the control relay JK is connected in series with the power supply circuit of the large transformation ratio power-off delay relay J1, and the protection relay JB is powered by the power supply.

When in use, the user can use a remote Bluetooth wireless device or other input device to send the small ratio current upper limit set value and the large ratio current lower limit set value to the MCU microprocessor through the communication interface, and the sampling current transformer CT1 collects the complex ratio in real time. The output current of the measuring secondary winding of the current transformer body CT is converted into a voltage signal by the sampling resistor R, and the voltage signal is processed by the RMS processing circuit module to obtain the effective value of the voltage signal, and the effective value of the voltage signal is transmitted to the A/D. The conversion module is sent to the MCU microprocessor after the analog-to-digital conversion of the A/D conversion module. With the support of the corresponding software, the MCU microprocessor converts the effective value of the voltage signal into the corresponding current acquisition value, and compares it with the small transformation ratio. The current upper limit setting value is compared with the large ratio current lower limit setting value. When the current collection value is less than the set value of the current lower limit of the large ratio, the MCU microprocessor makes the control relay JK electrified, its normally closed contact is disconnected, and the normally open contact is closed, so that the large ratio power-off delay relay J1 is delayed. When the power is cut off, the power-off delay relay J2 of the size ratio is charged and the normally open contact J2-1 is closed, and the normally open contact J1-1 of the large ratio power-off delay relay J1 is delayed and disconnected. The CT body CT of the complex ratio current transformer switches from the large ratio state to the small ratio state; on the contrary, when the current collection value is greater than the upper limit setting value of the small ratio current, the MCU microprocessor de-energizes the control relay JK, which is normally closed The contact is closed and the normally open contact is disconnected, so that the large ratio power-off delay relay J1 is charged, the size ratio shared power-off delay relay J2 delays power-off, and the large ratio power-off delay relay J1 is normally open. The contact J1-1 is closed, and the normally open contact J2-1 of the size ratio shared power-off delay relay J2 is delayed and disconnected (at the same time, the normally closed contact J2-2 of the size ratio shared power-off delay relay J2 is delayed. closed at the same time; the normally closed contact J2-2 of the power-off delay relay J2 shared by the size ratio ensures that the complex ratio current transformer is stably in the large ratio state when it starts to prevent the secondary open circuit under the startup transient, because The specification strictly prohibits the secondary open circuit under any circumstances), the CT of the complex ratio current transformer body is switched from the small ratio state to the large ratio state; when the power is accidentally cut off in the small ratio state, the normally closed contact of the protection relay JB JB-1 immediately turns on the secondary circuit of the large ratio, to prevent the instantaneous secondary open circuit caused by the shared power-off delay relay J2 of the large and small ratios during the delay disconnection.

The on-line intelligent switching complex ratio current transformer of the invention can realize the on-line automatic switching of the variable ratio, and has protection measures to prevent secondary open circuit; the structure design is reasonable and unique, and solves the problem of the existing complex ratio current transformer. The problem that cannot be automatically converted online can effectively avoid equipment damage and personal injury accidents. The present invention is suitable for electric energy metering devices.

Description of drawings

FIG. 1 is a schematic structural diagram of the present invention.

Detailed ways

The complex ratio current transformer for online intelligent conversion includes the complex ratio current transformer body CT, the sampling current transformer CT1, the RMS processing circuit module, the A/D conversion module, the MCU microprocessor with the communication interface, the protection relay JB, Control relay JK, common power-off delay relay J2 for large and small ratios, and power-off delay relay J1 for large ratio; Common tap terminal 1S1, small ratio tap terminal 1S2 and large ratio tap terminal 1S3; the common tap terminal 1S1 is coupled with the primary winding of the sampling current transformer CT1 as the polarity terminal of the secondary winding for measurement; the small ratio tap terminal 1S2 It is connected with one end of the normally open contact J2-1 of the power-off delay relay J2 shared by the size ratio, and the other end of the normally open contact J2-1 of the power-off delay relay J2 shared by the size ratio is used as the measurement secondary winding. The common non-polar terminal 1COM; the large ratio tap terminal 1S3 shares one end of the normally closed contact J2-2 of the power-off delay relay J2 with the size ratio and the normally open contact of the large ratio power-off delay relay J1 One end of J1-1 is connected to one end of the normally closed contact JB-1 of the protection relay JB, and the size ratio shares the other end of the normally closed contact J2-2 of the power-off delay relay J2, and the large ratio power-off delay relay The other end of the normally open contact J1-1 of J1 and the other end of the normally closed contact JB-1 of the protection relay JB are all connected to the common non-polar terminal 1COM; both ends of the secondary winding of the sampling current transformer CT1 are connected There is a sampling resistor R, one end of the sampling resistor R is grounded, and the other end is connected to the input of the RMS processing circuit module, the output of the RMS processing circuit module is connected to the input of the A/D conversion module, and the output of the A/D conversion module is connected to the MCU microprocessor. The input of the controller is connected, the output of the MCU microprocessor controls the electrification and de-energization of the control relay JK, and the normally open contact of the control relay JK is connected in series in the power supply circuit of the power-off delay relay J2 shared by the size ratio and the control relay. The normally closed contact of JK is connected in series with the power supply circuit of the large transformation ratio power-off delay relay J1, and the protection relay JB is powered by the power supply.

In the specific implementation, both ends of the power-off delay relay J2 with a large ratio and a large ratio are connected in parallel with a small ratio indicator M1, and both ends of the large ratio power-off delay relay J1 are connected in parallel with a large ratio indicator M2; The electric delay relay J1 and the size ratio share the power-off delay relay J2 to prevent the secondary open circuit during the switching process and increase the smooth transition between the large and small ratios. The communication interface of MCU microprocessor is RS232 interface or bluetooth interface.

The other secondary windings of the composite transformation ratio current transformer body CT also have a common tap end 2S1, a small transformation ratio tap end 2S2 and a large transformation ratio tap end 2S3, and each other secondary winding corresponds to a large and small transformation ratio. Time relay J4 and a large ratio power-off delay relay J3, the small ratio tap end 2S2 of the secondary winding (that is, each of the other secondary windings mentioned above) is shared with the size ratio corresponding to the secondary winding. One end of the normally open contact J4-1 of the electric delay relay J4 is connected, and the other end of the normally open contact J4-1 of the power-off delay relay J4 is shared with the size ratio corresponding to the secondary winding as the secondary winding The common non-polar terminal 2COM; the large change ratio tap terminal 2S3 of the secondary winding also shares one end of the normally closed contact J4-2 of the power-off delay relay J4 with the corresponding size change ratio of the secondary winding. One end of the normally open contact J3-1 of the large transformation ratio power-off delay relay J3 corresponding to the secondary winding is connected to one end of JB-2, one of the other normally closed contacts of the protection relay JB, corresponding to the secondary winding The size change ratio shares the other end of the normally closed contact J4-2 of the power-off delay relay J4, and the other end of the normally open contact J3-1 of the power-off delay relay J3 corresponding to the secondary winding. and the other end of JB-2, one of the other normally closed contacts of the protection relay JB, is all connected to the common non-polar end 2COM of the secondary winding; Relay J4 is connected in parallel with the power-off delay relay J2 corresponding to the size ratio corresponding to the metering secondary winding. The power-off delay relays J1 are connected in parallel with each other; in this way, other secondary windings can switch between large and small transformation ratio states simultaneously with the metering secondary winding connected with the sampling current transformer CT1.

Claims (3)

1. A complex ratio current transformer for online intelligent conversion is characterized by comprising a complex ratio current transformer body CT, a sampling current transformer CT1, an RMS processing circuit module, an A/D conversion module, an MCU microprocessor with a communication interface, a protection relay JB, a control relay JK, a large and small ratio common power-off delay relay J2 and a large ratio power-off delay relay J1; any one secondary winding of the complex ratio current transformer body CT is selected as a metering secondary winding, and the metering secondary winding is provided with a common tap end 1S1, a small-transformation-ratio tap end 1S2 and a large-transformation-ratio tap end 1S 3; the common tap end 1S1 is coupled with the primary winding of the sampling current transformer CT1 and then serves as a polarity end of the metering secondary winding; the small transformation ratio tapping end 1S2 is connected with one end of a normally open contact J2-1 of a large and small transformation ratio common outage delay relay J2, and the other end of the normally open contact J2-1 of the large and small transformation ratio common outage delay relay J2 is used as a common non-polar end 1COM of a metering secondary winding; the large transformation ratio tapping end 1S3 is simultaneously connected with one end of a normally closed contact J2-2 of a large and small transformation ratio common outage delay relay J2, one end of a normally open contact J1-1 of the large transformation ratio outage delay relay J1 and one end of a normally closed contact JB-1 of a protection relay JB, and the other end of a normally closed contact J2-2 of a large and small transformation ratio common outage delay relay J2, the other end of a normally open contact J1-1 of a large transformation ratio outage delay relay J1 and the other end of a normally closed contact JB-1 of the protection relay JB are all connected to a common non-polar end 1 COM; two ends of a secondary winding of the sampling current transformer CT1 are connected with a sampling resistor R, one end of the sampling resistor R is grounded, the other end of the sampling resistor R is connected with the input of an RMS processing circuit module, the output of the RMS processing circuit module is connected with the input of an A/D conversion module, the output of the A/D conversion module is connected with the input of an MCU microprocessor, the output end of the MCU microprocessor controls the electrification and the power loss of a control relay JK, a normally open contact of the control relay JK is connected in series with a power supply loop of a large-transformation ratio power-off delay relay J2, a normally closed contact of the control relay JK is connected in series with a power supply loop of the large-transformation ratio power-off delay relay J1, and a protection; the communication interface of the MCU microprocessor is an RS232 interface or a Bluetooth interface; a user adopts remote Bluetooth wireless equipment or other input equipment to send a small transformation ratio current upper limit set value and a large transformation ratio current lower limit set value to an MCU microprocessor through a communication interface, a sampling current transformer CT1 collects the output current of a metering secondary winding of a complex ratio current transformer body CT in real time, the output current is converted into a voltage signal through a sampling resistor R, the voltage signal is processed through an RMS processing circuit module to obtain a voltage signal effective value, the voltage signal effective value is transmitted to an A/D conversion module, the voltage signal effective value is transmitted to the MCU microprocessor after analog-to-digital conversion of the A/D conversion module, and the MCU microprocessor converts the voltage signal effective value into a corresponding current collection value and compares the current collection value with the small transformation ratio current upper limit set value and the large transformation ratio current lower limit set value; when the current collection value is smaller than the lower limit set value of the large transformation ratio current, the MCU microprocessor enables the control relay JK to be electrified, the normally closed contact of the control relay JK is opened, the normally open contact of the control relay JK is closed, the large transformation ratio power-off delay relay J1 is delayed to lose power, the normally open contact J1-1 of the large transformation ratio power-off delay relay J1 is delayed to be opened, the large transformation ratio power-off delay relay J2 is electrified to enable the normally open contact J2-1 of the large transformation ratio power-off delay relay J2 to be closed, and the CT body of the complex ratio current transformer is switched from; on the contrary, when the current collection value is larger than the upper limit set value of the small transformation ratio current, the MCU microprocessor enables the control relay JK to lose power, the normally closed contact of the control relay JK is closed, the normally open contact of the control relay JK is opened, the large transformation ratio power-off delay relay J1 is electrified, the large transformation ratio power-off delay relay J2 delays power loss, the normally open contact J1-1 of the large transformation ratio power-off delay relay J1 is closed, the normally open contact J2-1 of the large transformation ratio power-off delay relay J2 delays power off, and the body CT of the complex ratio current transformer is switched to the large transformation ratio state from the small transformation ratio state.

2. The on-line intelligent switching complex ratio current transformer of claim 1, characterized in that both ends of the large and small transformation ratio common power-off delay relay J2 are connected in parallel with a small transformation ratio indicator lamp M1, and both ends of the large transformation ratio power-off delay relay J1 are connected in parallel with a large transformation ratio indicator lamp M2.

3. The on-line intelligent conversion complex ratio current transformer according to claim 1 or 2, characterized in that other secondary windings of the composite transformation ratio current transformer body CT also have a common tap end 2S1, a small transformation ratio tap end 2S2 and a large transformation ratio tap end 2S3, each of the other secondary windings respectively corresponds to a large and small transformation ratio common outage delay relay J4 and a large transformation ratio outage delay relay J3, the small transformation ratio tap end 2S2 of the secondary winding is connected with one end of a normally open contact J4-1 of the large and small transformation ratio common outage delay relay J4 corresponding to the secondary winding, and the other end of the normally open contact J4-1 of the large and small transformation ratio common outage delay relay J4 corresponding to the secondary winding is used as a common non-polar end 2COM of the secondary winding; the large transformation ratio tap end 2S3 of the secondary winding is simultaneously connected with one end of a normally closed contact J4-2 of a large transformation ratio common outage delay relay J4 corresponding to the secondary winding, one end of a normally open contact J3-1 of the large transformation ratio common outage delay relay J3 corresponding to the secondary winding and one end of one JB-2 of other normally closed contacts of a protection relay JB, and the other end of the normally closed contact J4-2 of the large transformation ratio common outage delay relay J4 corresponding to the secondary winding, the other end of the normally open contact J3-1 of the large transformation ratio outage delay relay J3 corresponding to the secondary winding and the other end of one JB-2 of the other normally closed contacts of the protection relay JB are all connected to the common non-polar end 2COM of the secondary winding; the large-to-small ratio common power-off delay relay J4 corresponding to other secondary windings and the large-to-small ratio common power-off delay relay J2 corresponding to the metering secondary winding are connected in parallel, and the large-to-large ratio power-off delay relay J3 corresponding to other secondary windings and the large-to-large ratio power-off delay relay J1 corresponding to the metering secondary winding are connected in parallel.

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