A kind of intelligent reactive power compensation module control circuit and control method thereof

Abstract

The present invention discloses an intelligent reactive power compensation module control circuit, comprising a low-voltage power capacitor body C, a main switch Z, a microprocessor circuit M, a switch circuit A1, a switch circuit A2, a voltage detection circuit V1, a voltage detection circuit V2, a current detection circuit I, a temperature acquisition circuit W, a communication circuit T, a power supply circuit P and a human-machine contact module R, wherein the switch circuit A1, the switch circuit A2, the voltage detection circuit V1, the voltage detection circuit V2, the current detection circuit I, the temperature acquisition circuit W, the communication circuit T, the power supply circuit P and the human-machine contact module R are respectively connected to the microprocessor circuit M. The present invention solves the problems of inaccurate zero-crossing detection of conventional reactive power compensation capacitors, large switching inrush current, easy damage to capacitor banks, etc. in the case of harmonics or interference in the capacitor switching process, and improves the reliability of reactive power compensation.

Description

Technical Field

[0001] The invention relates to a control circuit and a control method thereof, in particular to an intelligent reactive power compensation module control circuit and a control method thereof, and belongs to the field of power capacitor equipment. Background Art

[0002] Intelligent reactive power compensation capacitor is an intelligent reactive power compensation device that integrates modern measurement and control, power electronics, network communication, automation control, power capacitor and other advanced technologies. Intelligent reactive power compensation capacitor has changed the backward control technology of traditional reactive power compensation devices and the backward mechanical contactor or mechatronic switch as the switching technology of switching capacitors, and changed the bulky and heavy structural mode of traditional reactive power compensation devices, so that the new generation of low-voltage reactive power compensation equipment has better compensation effect, smaller size, lower power consumption, cheaper price, more cost savings, more flexible use, more convenient maintenance, longer service life, higher reliability, and meets the higher requirements of modern power grids for reactive power compensation.

[0003] The reactive power compensation capacitors in the prior art need to be switched at zero, that is, the zero point of the system voltage needs to be detected, and then the switch is controlled to switch at this zero point. However, in the case of harmonics or interference during the capacitor switching process, the control module will misjudge the zero point, resulting in switching at a false zero point, causing large switching inrush current, leading to damage to the capacitor bank and other problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an intelligent reactive power compensation module control circuit and a control method thereof, so as to improve the reliability of switching of reactive power compensation capacitors.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An intelligent reactive power compensation module control circuit, characterized in that: it comprises a low-voltage power capacitor body C, a main switch Z, a microprocessor circuit M, a switch circuit A1, a switch circuit A2, a voltage detection circuit V1, a voltage detection circuit V2, a current detection circuit I, a temperature acquisition circuit W, a communication circuit T, a power supply circuit P and a human-machine contact module R, and the switch circuit A1, the switch circuit A2, the voltage detection circuit V1, the voltage detection circuit V2, the current detection circuit I, the temperature acquisition circuit W, the communication circuit T, the power supply circuit P and the human-machine contact module R are respectively connected to the microprocessor Circuit M is connected, the main switch Z is connected to the low-voltage power capacitor body C in three phases, the switch circuit A1 and the switch circuit A2 are respectively arranged on the a and c two-phase lines between the main switch Z and the low-voltage power capacitor body C, the voltage detection circuit V1 detects the voltage across the switch circuit A1, the voltage detection circuit V2 detects the voltage across the switch circuit A2, the current detection circuit I respectively detects the a and c two-phase line currents between the main switch Z and the low-voltage power capacitor body C, the temperature acquisition circuit W is arranged in the low-voltage power capacitor body C, and the power supply circuit P provides working power for each circuit.

[0007] Furthermore, the main switch Z is a circuit breaker or a fuse.

[0008] Furthermore, the communication circuit T is provided with an RS-485 communication interface, and each intelligent reactive power compensation module communicates with each other and with the reactive power compensation controller via the RS-485 communication interface.

[0009] Furthermore, the human-machine contact module R adopts a liquid crystal screen or a digital tube, and the microprocessor circuit M displays the measured and calculated line voltage, current, power factor, active power, reactive power and operating parameters and status of the capacitor through the human-machine contact module R, and the human-machine contact module R saves the manually set parameter information in the microprocessor circuit M.

[0010] Further, the switch circuit A1 and the switch circuit A2 respectively include a unidirectional thyristor S1, a unidirectional thyristor S2, a first control circuit K1, a second control circuit K2, a relay J1 and a third control circuit K3, the unidirectional thyristor S1, the unidirectional thyristor S2 and the relay J1 are arranged in parallel between the two ends of the switch circuit A1 or the switch circuit A2, and the unidirectional thyristor S1 and the unidirectional thyristor S2 are connected in reverse parallel, the first control circuit K1 is respectively connected to the control end of the unidirectional thyristor S1 and the microprocessor circuit M, the second control circuit K2 is respectively connected to the control end of the unidirectional thyristor S2 and the microprocessor circuit M, and the third control circuit K3 is respectively connected to the control end of the relay J1 and the microprocessor circuit M.

[0011] Furthermore, the current measuring circuit I is connected to the line current sampling interface Y for detecting the line current signal transmitted by the external sampling current sensor, and the current detection circuit I is connected to the current sensor CT1 and the current sensor CT2 for detecting the capacitor current signal transmitted by the current sensor on the internal switch circuit.

[0012] A control method for an intelligent reactive power compensation module control circuit, characterized by comprising the following steps:

[0013] The closing process of the switch circuit controlled by the microprocessor circuit M is:

[0014] 1) The voltage detection circuit V detects the voltage signal between the switch circuits U1 and U2. When the switch circuit is in the off state, the voltage signal is a sine wave. A control signal is sent out during the negative half cycle t1 of the sine wave. The control signal is applied to the control electrode G and cathode K of the unidirectional thyristor S1 through the first control circuit K1;

[0015] 2) In the positive half cycle t2 period of the sine wave, a control signal is applied to the control electrode G and cathode K of the unidirectional thyristor S2 through the second control circuit K2;

[0016] 3) In the negative half cycle t3 of the sine wave or in the period thereafter, the third control circuit K3 controls the relay J1 to close, and the switch circuit A is closed;

[0017] When the microprocessor circuit M controls the switch circuit to open:

[0018] 1) Disconnect the relay J1 through the third control circuit K3, and wait for the relay J1 to disconnect completely;

[0019] 2) The control signals on the control electrode G and cathode K of the unidirectional thyristor S1 are cancelled through the first control circuit K1, and the control signals on the control electrode G and cathode K of the unidirectional thyristor S2 are cancelled through the second control circuit K2, and the switch circuit A is disconnected.

[0020] Compared with the prior art, the present invention has the following advantages and effects: the intelligent reactive power compensation module control circuit and control method of the present invention do not need to detect the zero-crossing point and control the switch action at the zero-crossing point during the process of controlling the closing and opening of the switch circuit, and only need to complete the control in the corresponding time period to achieve zero-voltage closing and current zero-crossing opening at both ends of the switch circuit A; the problems of inaccurate zero-crossing point detection of conventional reactive power compensation capacitors, large switching inrush current, and easy damage to the capacitor group in the presence of harmonics or interference during the switching process of the capacitor are solved, thereby improving the reliability of reactive power compensation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of an intelligent reactive power compensation module control circuit of the present invention.

[0022] Figure 2 Schematic diagram of the switch circuit of the present invention.

[0023] Figure 3 It is a time period diagram of an intelligent reactive power compensation module control method of the present invention. DETAILED DESCRIPTION

[0024] In order to elaborate on the technical scheme adopted by the present invention to achieve the predetermined technical purpose, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only partial embodiments of the present invention, rather than all embodiments, and the technical means or technical features in the embodiments of the present invention can be replaced without paying creative work. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0025] like Figure 1 As shown, an intelligent reactive power compensation module control circuit of the present invention comprises a low-voltage power capacitor body C, a main switch Z, a microprocessor circuit M, a switch circuit A1, a switch circuit A2, a voltage detection circuit V1, a voltage detection circuit V2, a current detection circuit I, a temperature acquisition circuit W, a communication circuit T, a power supply circuit P and a human-machine contact module R, wherein the switch circuit A1, the switch circuit A2, the voltage detection circuit V1, the voltage detection circuit V2, the current detection circuit I, the temperature acquisition circuit W, the communication circuit T, the power supply circuit P and the human-machine contact module R are respectively connected to the microprocessor Circuit M is connected, the main switch Z is connected to the low-voltage power capacitor body C in three phases, the switch circuit A1 and the switch circuit A2 are respectively arranged on the a and c two-phase lines between the main switch Z and the low-voltage power capacitor body C, the voltage detection circuit V1 detects the voltage across the switch circuit A1, the voltage detection circuit V2 detects the voltage across the switch circuit A2, the current detection circuit I respectively detects the a and c two-phase line currents between the main switch Z and the low-voltage power capacitor body C, the temperature acquisition circuit W is arranged in the low-voltage power capacitor body C, and the power supply circuit P provides working power for each circuit.

[0026] The temperature acquisition circuit W is arranged in the low-voltage power capacitor body C, which is connected to the microprocessor circuit M and is used to detect the capacitor temperature and realize the capacitor over-temperature protection. The main switch Z can be a circuit breaker or a fuse, and its outlet terminals are respectively connected to the switch circuit A1, the switch circuit A2 and one phase of the capacitor body, and the other two phases of the capacitor body are respectively connected to the switch circuit A1 and the switch circuit A2. When the intelligent reactive power compensation module is short-circuited or over-current occurs, the main switch Z is disconnected to cut off the main circuit power supply.

[0027] The microprocessor circuit M is connected to the voltage detection circuit V, the current detection circuit I, the temperature sensor W, the communication circuit T and the human-machine contact module R, and calculates the voltage, current, power factor, active power, reactive power and other parameters of the line according to the detected voltage signal and current signal, and then automatically controls or receives the control command to put the low-voltage power capacitor body C into or out through the control switch circuit A1 and the switch circuit A2 according to the calculated parameters and the state of the capacitor itself.

[0028] The communication circuit T is connected to the microprocessor circuit M. The communication circuit T has an RS-485 communication interface to the outside. Each intelligent reactive compensation module and the reactive compensation controller communicate online through this communication interface. The human-machine contact module R uses a liquid crystal screen or a digital tube. The microprocessor circuit M displays the measured and calculated line voltage, current, power factor, active power, reactive power, and the operating parameters and status of the capacitor through the human-machine contact module R. At the same time, the human-machine contact module R saves the manually set parameter information in the microprocessor circuit M.

[0029] The switch circuit A1 and the switch circuit A2 respectively control the two-phase circuit of the low-voltage power capacitor body C. Figure 2 As shown, the switch circuit A1 and the switch circuit A2 respectively include a unidirectional thyristor S1, a unidirectional thyristor S2, a first control circuit K1, a second control circuit K2, a relay J1 and a third control circuit K3. The unidirectional thyristor S1, the unidirectional thyristor S2 and the relay J1 are arranged in parallel between the two ends of the switch circuit A1 or the switch circuit A2, and the unidirectional thyristor S1 and the unidirectional thyristor S2 are connected in reverse parallel. The first control circuit K1 is respectively connected to the control end of the unidirectional thyristor S1 and the microprocessor circuit M, the second control circuit K2 is respectively connected to the control end of the unidirectional thyristor S2 and the microprocessor circuit M, and the third control circuit K3 is respectively connected to the control end of the relay J1 and the microprocessor circuit M.

[0030] The voltage detection circuit V1 and the voltage detection circuit V2 detect the voltage signals at both ends of the switch circuit A1 and the switch circuit A2 respectively, and transmit them to the microprocessor circuit M, and provide input power to the power supply circuit P. The current detection circuit I is connected to the line current sampling interface Y to detect the line current signal transmitted by the external sampling current sensor, and the current detection circuit I is connected to the current sensor CT1 and the current sensor CT2 to detect the capacitor current signal transmitted by the current sensor on the internal switch circuit.

[0031] like Figure 3 As shown, a control method for an intelligent reactive power compensation module control circuit comprises the following steps:

[0032] The closing process of the switch circuit controlled by the microprocessor circuit M is:

[0033] 1) The voltage detection circuit V detects the voltage signal between the switch circuits U1 and U2. When the switch circuit is in the disconnected state, the voltage signal is a sine wave. A control signal is sent out during the negative half cycle t1 of the sine wave, and a control signal is added to the control electrode G and cathode K of the unidirectional thyristor S1 through the first control circuit K1. At this time, the switch circuit voltage signal is opposite to the conduction direction of the unidirectional thyristor S1, and the unidirectional thyristor S1 has no current. Controlling the conduction of the unidirectional thyristor S1 will not cause inrush current problems.

[0034] 2) In the positive half cycle t2 time period of the sine wave, a control signal is added to the control electrode G and cathode K of the unidirectional thyristor S2 through the second control circuit K2; at this time, the voltage signal of the switching circuit is opposite to the conduction direction of the unidirectional thyristor S2, and the unidirectional thyristor S2 has no current. Controlling the conduction of the unidirectional thyristor S2 will not cause inrush current problems, and the actual current forms a loop from the unidirectional thyristor S1.

[0035] 3) In the negative half cycle t3 of the sine wave or the period thereafter, the third control circuit K3 controls the relay J1 to close, and the switch circuit A is closed; at this time, the thyristors S1 and S2 have formed a loop, and a new loop is formed when the relay J1 is closed, and no large inrush current problem will occur.

[0036] The entire closing process does not require detection of the zero-crossing point, nor does it require control of the switch action at the zero-crossing point. It only needs to complete the control in the corresponding time period to achieve zero-voltage closing at both ends of the switch circuit A.

[0037] When the microprocessor circuit M controls the switch circuit to open:

[0038] 1) Disconnect the relay J1 through the third control circuit K3, and wait for the relay J1 to disconnect completely;

[0039] 2) The control signals on the control electrode G and cathode K of the thyristor S1 are cancelled through the first control circuit K1, and the control signals on the control electrode G and cathode K of the thyristor S2 are cancelled through the second control circuit K2, and the switch circuit A is disconnected. Due to the characteristics of the thyristor S2 itself, as long as there is current, it will not be turned off immediately even if the control signal is cut off, but it will be turned off only when the current signal is 0. In this way, when the current passes through the 0 point, the thyristor S2 will be turned off to achieve automatic zero point control. Based on this principle, when the thyristor is opened, there is no need to consider the time period. Regardless of whether the sine wave is in the positive cycle or the negative cycle, when the current direction is opposite to that of a thyristor, the thyristor has no current and can be directly cut off. At this time, the other thyristor is in the same direction as the current. After the control signal is cut off, it is automatically cut off at the current 0 point.

[0040] The entire opening process does not require detection of the zero-crossing point, nor does it require control of the switch action at the zero-crossing point. The current zero-crossing opening of the switch circuit A can be achieved by completing the control in the corresponding time period.

[0041] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A control method for an intelligent reactive power compensation module control circuit, The intelligent reactive power compensation module control circuit comprises a low-voltage power capacitor body C, a main switch Z, a microprocessor circuit M, a switch circuit A1, a switch circuit A2, a voltage detection circuit V1, a voltage detection circuit V2, a current detection circuit I, a temperature acquisition circuit W, a communication circuit T, a power supply circuit P and a human-machine contact module R. The switch circuit A1, the switch circuit A2, the voltage detection circuit V1, the voltage detection circuit V2, the current detection circuit I, the temperature acquisition circuit W, the communication circuit T, the power supply circuit P and the human-machine contact module R are respectively connected to the microprocessor circuit M, the main switch Z is connected to the low-voltage power capacitor body C in three phases, the switch circuit A1 and the switch circuit A2 are respectively arranged on the a and c two-phase lines between the main switch Z and the low-voltage power capacitor body C, the voltage detection circuit V1 detects the voltage across the switch circuit A1, the voltage detection circuit V2 detects the voltage across the switch circuit A2, the current detection circuit I respectively detects the a and c two-phase line currents between the main switch Z and the low-voltage power capacitor body C, the temperature acquisition circuit W is arranged in the low-voltage power capacitor body C, and the power supply circuit P provides working power for each circuit; The switch circuit A1 and the switch circuit A2 respectively include a unidirectional thyristor S1, a unidirectional thyristor S2, a first control circuit K1, a second control circuit K2, a relay J1 and a third control circuit K3, the unidirectional thyristor S1, the unidirectional thyristor S2 and the relay J1 are arranged in parallel between the two ends of the switch circuit A1 or the switch circuit A2, and the unidirectional thyristor S1 and the unidirectional thyristor S2 are connected in reverse parallel, the first control circuit K1 is respectively connected to the control end of the unidirectional thyristor S1 and the microprocessor circuit M, the second control circuit K2 is respectively connected to the control end of the unidirectional thyristor S2 and the microprocessor circuit M, and the third control circuit K3 is respectively connected to the control end of the relay J1 and the microprocessor circuit M; Features The following steps are involved: The closing process of the switch circuit controlled by the microprocessor circuit M is: 1) The voltage detection circuit V detects the voltage signal between the switch circuits U1 and U2. When the switch circuit is in the off state, the voltage signal is a sine wave. A control signal is sent out during the negative half cycle t1 of the sine wave. The control signal is applied to the control electrode G and cathode K of the unidirectional thyristor S1 through the first control circuit K1; 2) In the positive half cycle t2 period of the sine wave, a control signal is applied to the control electrode G and cathode K of the unidirectional thyristor S2 through the second control circuit K2; 3) In the negative half cycle t3 of the sine wave or in the period thereafter, the third control circuit K3 controls the relay J1 to close, and the switch circuit A is closed; When the microprocessor circuit M controls the switch circuit to open: 1) Disconnect the relay J1 through the third control circuit K3, and wait for the relay J1 to disconnect completely; 2) The control signals on the control electrode G and cathode K of the unidirectional thyristor S1 are cancelled through the first control circuit K1, and the control signals on the control electrode G and cathode K of the unidirectional thyristor S2 are cancelled through the second control circuit K2, and the switch circuit A is disconnected.

2. The control method of the intelligent reactive power compensation module control circuit according to claim 1, characterized in that: The main switch Z is a circuit breaker or a fuse.

3. The control method of the intelligent reactive power compensation module control circuit according to claim 1, characterized in that: The communication circuit T is provided with an RS-485 communication interface, and each intelligent reactive power compensation module communicates with each other and with the reactive power compensation controller via the RS-485 communication interface.

4. The control method of the intelligent reactive power compensation module control circuit according to claim 1, characterized in that: The human-machine contact module R adopts a liquid crystal screen or a digital tube, and the microprocessor circuit M displays the measured and calculated line voltage, current, power factor, active power, reactive power and the operating parameters and status of the capacitor through the human-machine contact module R. At the same time, the human-machine contact module R saves the manually set parameter information in the microprocessor circuit M.

5. The control method of the intelligent reactive power compensation module control circuit according to claim 1, characterized in that: The current measuring circuit I is connected to the line current sampling interface Y for detecting the line current signal transmitted by the external sampling current sensor, and the current detecting circuit I is connected to the current sensor CT1 and the current sensor CT2 for detecting the capacitor current signal transmitted by the current sensor on the internal switch circuit.

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