An AC voltage stabilization system with reactive power compensation

Abstract

The present invention discloses an AC voltage stabilization system with reactive power compensation, which mainly solves the problems of poor power quality of existing power grids and slow response speed of existing power grid voltage stabilizers. The AC voltage stabilization system includes a three-phase power input terminal and a three-phase power output terminal, a three-phase transformer with one end of the primary winding connected to the three-phase power input terminal, a three-phase rectifier circuit connected to the three-phase power input terminal, and a dual-core total control unit, an AC voltage stabilization unit connected to both the dual-core total control unit and the three-phase rectifier circuit, and a reactive power compensation unit connected to the dual-core total control unit and the three-phase power input terminal. Through the above design, the system can effectively stabilize the grid voltage and realize dynamic reactive power compensation of the grid at the same time, and has fast response speed, low cost, and convenient maintenance, and can effectively improve the actual output capacity and power quality of the grid. Therefore, it is suitable for promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of power grid power supply, and in particular to an AC voltage stabilizing system with reactive power compensation. Background Art

[0002] With the improvement of living standards and the popularization of high-power household appliances, the electricity consumption of residential users has increased significantly year by year. However, the transformation of the distribution network in some factories, mines, residential areas, and remote areas is relatively lagging, resulting in generally low voltage at the end of the power grid. At the same time, the voltage of the power grid fluctuates greatly, and the power grid is generally overloaded, causing some high-power appliances such as air conditioners and rice cookers to fail to work properly, causing great harm to electrical equipment. At the same time, a large number of new electrical equipment use nonlinear electrical equipment such as motors and compressors. Especially in factories and mines, due to the widespread use of large asynchronous motors, cranes, electric traction, etc., these devices generally have low power factors and generate a large amount of reactive power when working. On the one hand, they consume a large amount of reactive power, bringing additional burden to the power grid, and on the other hand, they seriously affect the power quality of the power grid.

[0003] The best solution to the above-mentioned problems of low grid voltage, large grid voltage fluctuations, and poor grid power quality is to add an automatic voltage regulation and reactive power compensation system to the grid to stabilize the grid voltage within the standard voltage range, while compensating for the grid reactive power in real time, which can effectively improve the actual output capacity and power quality of the grid and protect the safety of power consumption of electrical equipment.

[0004] The voltage stabilizer currently used in China consists of a voltage regulating circuit, a control circuit, and a servo motor. When the input voltage or load changes, the control circuit samples, compares, and amplifies, and then drives the servo motor to rotate, so that the position of the voltage regulator carbon brush changes, and the output voltage is kept stable by automatically adjusting the coil turns ratio. This type of voltage stabilizer has a slow response speed and is powerless when the grid voltage fluctuates rapidly. Summary of the invention

[0005] The purpose of the present invention is to provide an AC voltage stabilization system with reactive power compensation, which mainly solves the problems of poor power quality of existing power grids and slow response speed of existing power grid voltage stabilizers.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] An AC voltage stabilization system with reactive power compensation comprises a three-phase power input terminal and a three-phase power output terminal, a three-phase transformer having one end of a primary winding connected to the three-phase power input terminal, and a three-phase rectifier circuit connected to the three-phase power input terminal, wherein the other end of the primary winding of the three-phase transformer is connected to the three-phase power output terminal; further comprising a dual-core general control unit, an AC voltage stabilization unit connected to both the dual-core general control unit and the three-phase rectifier circuit, and a reactive power compensation unit connected to the dual-core general control unit and the three-phase power input terminal; the reactive power compensation unit comprises a circuit breaker having one end connected to the three-phase power input terminal, and a main contactor connected to the other end of the circuit breaker. a first DC voltage detection circuit having an input end connected to the first DC filter circuit and an output end connected to the dual-core general control unit; a first inverter output current detection circuit having an input end connected to the AC side of the first three-phase inverter circuit and an output end connected to the dual-core general control unit; and a load current detection circuit having an input end connected to the output end of the three-phase power supply and an output end connected to the dual-core general control unit.

[0008] Furthermore, the AC voltage stabilization unit includes a second DC filter circuit whose positive and negative ends are connected to the positive and negative ends of the three-phase rectifier circuit output, a second DC voltage detection circuit whose input end is connected to the positive and negative ends of the second DC filter circuit and whose output end is connected to the dual-core general control unit, a second three-phase inverter circuit whose AC side is connected to the secondary winding of the three-phase transformer, a second inverter output current detection circuit whose input end is connected to the AC side of the second three-phase inverter circuit and whose output end is connected to the dual-core general control unit, a bypass circuit breaker connected in parallel to the corresponding winding of the primary side of the three-phase transformer, and an AC voltage detection circuit whose input end is connected to the three-phase power supply input end and whose output end is connected to the dual-core general control unit.

[0009] Furthermore, the system also includes a human-computer interaction interface connected to the control unit via a signal bus.

[0010] Furthermore, the first DC filter circuit and the second DC filter circuit are composed of a plurality of electrolytic capacitors or film capacitors connected in series and in parallel.

[0011] Furthermore, the dual-core general control unit includes a main control chip of model TMS320F28377 that shares common data.

[0012] Furthermore, the first DC voltage detection circuit and the second DC voltage detection circuit are each composed of a DC voltage sensor and a signal conditioning circuit.

[0013] Furthermore, the first inverter output current detection circuit, the second inverter output current detection circuit, and the load current detection circuit are all composed of three current sensors and three signal conditioning circuits, and one current sensor is correspondingly connected to one signal conditioning circuit.

[0014] Furthermore, the AC voltage detection circuits are composed of three AC voltage sensors and three signal conditioning circuits; one AC voltage sensor is correspondingly connected to one signal conditioning circuit.

[0015] Furthermore, the signal conditioning circuit includes a sampling filter circuit, a differential amplifier circuit, a current limiting filter circuit, and a clamp circuit which are connected in sequence, and the signal is input from the sampling filter circuit and output from the clamp circuit.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The AC voltage stabilization system of the present invention has two working modes: independent mode and joint mode. In the independent mode, the voltage stabilization system can be selected to work alone or the compensation system can be selected to work alone. In the joint mode, the compensation system and the voltage stabilization system work at the same time, and the compensation system and the voltage stabilization system are linked, which has the best effect on improving the quality of the power grid. The system can effectively stabilize the voltage of the power grid and realize dynamic compensation for the reactive power of the power grid. It has fast response speed, low cost, and convenient maintenance, and can effectively improve the actual output capacity and power quality of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the overall structural circuit principle diagram of the present invention.

[0019] Figure 2 Schematic diagram of a signal conditioning circuit in an embodiment of the present invention.

[0020] The names corresponding to the reference numerals are:

[0021] 1-three-phase power input terminal, 2-three-phase rectifier circuit, 3-second DC filter circuit, 4-second three-phase inverter circuit, 5-second DC voltage detection circuit, 6-second inverter output current detection circuit, 7-dual-core main control unit, 8-three-phase transformer, 9-bypass circuit breaker, 10-AC voltage detection circuit, 11-load current detection circuit, 12-circuit breaker, 13-main contactor, 14-auxiliary contactor, 15-reactor, 16-first three-phase inverter circuit, 17-first DC filter circuit, 18-first inverter output current detection circuit, 19-first DC voltage detection circuit, 20-human-computer interaction interface, 21-three-phase power output terminal, 22-sampling filter circuit, 23-differential amplifier circuit, 24-current limiting filter circuit, 25-clamping circuit. DETAILED DESCRIPTION

[0022] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The embodiments of the present invention include but are not limited to the following embodiments.

[0023] Example

[0024] like Figure 1 , 2 As shown, the present invention discloses an AC voltage stabilization system with reactive power compensation, including a three-phase power input terminal 1 (U1, V1, W1) and a three-phase power output terminal 21 (U2, V2, W2), a three-phase transformer 8 having one end of a primary winding connected to the three-phase power input terminal, and a three-phase rectifier circuit 2 connected to the three-phase power input terminal 1, wherein the other end of the primary winding of the three-phase transformer 8 is connected to the three-phase power output terminal 21; further comprising a dual-core general control unit 7, an AC voltage stabilization unit connected to both the dual-core general control unit 7 and the three-phase rectifier circuit 2, and a reactive power compensation unit connected to the dual-core general control unit 7 and the three-phase power input terminal 1; the reactive power compensation unit includes a circuit breaker 12 having one end connected to the three-phase power input terminal 1, and a circuit breaker 12 having another end connected to the circuit breaker 12. a main contactor 13 connected to one end of the main contactor 13, an auxiliary contactor 14 connected in parallel to both ends of the main contactor 13, a reactor 15 connected to the other end of the main contactor 13, a first three-phase inverter circuit 16 connected to the other end of the reactor 15 on the AC side, a first DC filter circuit 17 connected to the positive and negative ends of the DC side of the first three-phase inverter circuit 16, a first DC voltage detection circuit 19 connected to the first DC filter circuit 17 at the input end and connected to the dual-core general control unit 7 at the output end, a first inverter output current detection circuit 18 connected to the AC side of the first three-phase inverter circuit 16 at the input end and connected to the dual-core general control unit 7 at the output end, and a load current detection circuit 11 connected to the three-phase power supply output terminal 21 at the input end and connected to the dual-core general control unit 7 at the output end.

[0025] In this embodiment, the system further includes a human-machine interaction interface 20 connected to the control unit via a signal bus to achieve data communication and status monitoring of the system.

[0026] In the reactive power compensation unit, the CPU1 of TMS320F28377 collects analog signals of the AC voltage detection circuit 10, the load current detection circuit 11, the first inverter output current detection circuit 18, and the first DC voltage detection circuit 19 to obtain the three-phase AC bus voltage Ua, Ub, Uc, the three-phase AC bus current Isa, Isb, Isc, and the reactive power compensation unit output current Ia, Ib, Ic. Phase locking is to calculate the power supply phase of the system input AC power supply through the three-phase phase-locked loop algorithm by collecting the three-phase AC bus voltage Ua, Ub, Uc. The sine and cosine are calculated from the power supply phase obtained by phase locking. The active and reactive components of the load are calculated by FFT, and the active current component Is_real and the reactive current component Is_imag of the reactive power compensation unit bus AC current are calculated by Fourier algorithm. The voltage-stabilized current component is calculated by FFT, and the active current component Iu_real of the voltage-stabilized current of the reactive compensation unit is calculated by Fourier algorithm from the power phase obtained by phase locking. Through the PI regulator of CPU1, the reactive compensation unit outputs a current in phase with Iu_real to achieve voltage stabilization, and outputs a current in the opposite direction of Is_imag to achieve reactive compensation.

[0027] In this embodiment, the AC voltage stabilizing unit includes a second DC filter circuit 3 whose positive and negative ends are connected to the positive and negative ends of the three-phase rectifier circuit output, a second DC voltage detection circuit 5 whose input end is connected to the positive and negative ends of the second DC filter circuit 3 and whose output end is connected to the dual-core general control unit 7, a second three-phase inverter circuit 4 whose AC side is connected to the secondary winding of the three-phase transformer 8, a second inverter output current detection circuit 6 whose input end is connected to the AC side of the second three-phase inverter circuit 4 and whose output end is connected to the dual-core general control unit 7, a bypass circuit breaker 9 connected in parallel to the corresponding winding of the primary side of the three-phase transformer 8, and an AC voltage detection circuit 10 whose input end is connected to the three-phase power supply input terminal 1 and whose output end is connected to the dual-core general control unit 7.

[0028] In the AC voltage stabilization unit, the CPU2 of TMS320F28377 collects analog signals of the AC voltage detection circuit 10, the second DC voltage detection circuit 5, and the second inverter output current detection circuit 6 to obtain the three-phase AC bus voltage Ua, Ub, Uc, the AC voltage stabilization unit DC bus voltage Udc_w, and the AC voltage stabilization unit output current Ia_w, Ib_w, Ic_w. The power supply phase of the AC power supply input to the system is calculated by a three-phase phase-locked loop algorithm. The sine and cosine are calculated from the power supply phase obtained by phase locking. The three-phase AC bus voltage is compared with the voltage stabilization preset value, and the regulated voltage component required by the AC voltage stabilization unit is output through the PI regulator of CPU2. The regulated voltage component is coupled to the primary side through the three-phase transformer 8 to achieve the purpose of voltage stabilization.

[0029] Among them, the first DC filter circuit 17 and the second DC filter circuit 3 are composed of multiple electrolytic capacitors or film capacitors connected in series and parallel. The first DC voltage detection circuit 19 and the second DC voltage detection circuit 5 are each composed of a DC voltage sensor and a signal conditioning circuit. The first inverter output current detection circuit 18, the second inverter output current detection circuit 6, and the load current detection circuit 11 are each composed of three current sensors and three signal conditioning circuits, and one current sensor is connected to one signal conditioning circuit. The AC voltage detection circuit 10 is composed of three AC voltage sensors and three signal conditioning circuits; one AC voltage sensor is connected to one signal conditioning circuit. Used to detect the AC voltage at the input end of the three-phase power supply.

[0030] The dual-core total control unit includes a main control chip of model TMS320F28377 that shares common data. The CPU1 of TMS320F28377 is the main control core of the compensation system, and the CPU2 of TMS320F28377 is the main control core of the voltage stabilization system. The CPU1 of TMS320F28377 and the CPU2 of TMS320F28377 can share common data, and the common data includes their respective states and operation information. The main functions of the CPU1 and CPU2 of TMS320F28377 include A / D sampling signal processing, phase-locked loop processing, FFT (Fourier) operation, voltage and current closed-loop operation, SVPWM calculation, etc.

[0031] The signal conditioning circuit includes a sampling filter circuit 22, a differential amplifier circuit 23, a current limiting filter circuit 24, and a clamping circuit 25 connected in sequence. The input signal V_IN is subjected to sampling filtering, differential amplification, current limiting filtering, and clamping to obtain an output signal V_AD. The signal V_AD is input to the analog-to-digital converter of the CPU for signal processing.

[0032] Through the above design, the system can effectively stabilize the grid voltage and realize dynamic compensation of grid reactive power. It has the advantages of fast response, low cost and convenient maintenance, and can effectively improve the actual output capacity and power quality of the grid. Therefore, it has high use value and promotion value.

[0033] The above embodiment is only one of the preferred implementation modes of the present invention and should not be used to limit the protection scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention.

Claims

1. An AC voltage stabilization system with reactive power compensation, comprising a three-phase power input terminal (1) and a three-phase power output terminal (21), a three-phase transformer (8) having one end of a primary winding connected to the three-phase power input terminal, and a three-phase rectifier circuit (2) connected to the three-phase power input terminal (1), wherein: The other end of the primary winding of the three-phase transformer (8) is connected to the three-phase power supply output terminal (21); the transformer is characterized in that it also includes a dual-core general control unit (7), an AC voltage stabilizing unit connected to both the dual-core general control unit (7) and the three-phase rectifier circuit (2), and a reactive power compensation unit connected to the dual-core general control unit (7) and the three-phase power supply input terminal (1); the reactive power compensation unit includes a circuit breaker (12) connected to the three-phase power supply input terminal (1) at one end, a main contactor (13) connected to the other end of the circuit breaker (12), an auxiliary contactor (14) connected in parallel to both ends of the main contactor (13), a reactor (15) connected to the other end of the main contactor (13), and an AC A first three-phase inverter circuit (16) having a current side connected to the other end of the reactor (15), a first DC filter circuit (17) connected to the positive and negative ends of the DC side of the first three-phase inverter circuit (16), a first DC voltage detection circuit (19) having an input end connected to the first DC filter circuit (17) and an output end connected to the dual-core general control unit (7), a first inverter output current detection circuit (18) having an input end connected to the AC side of the first three-phase inverter circuit (16) and an output end connected to the dual-core general control unit (7), and a load current detection circuit (11) having an input end connected to the three-phase power supply output end (21) and an output end connected to the dual-core general control unit (7); The AC voltage stabilizing unit comprises a second DC filter circuit (3) whose positive and negative ends are connected to the positive and negative ends of the output of the three-phase rectifier circuit, a second DC voltage detection circuit (5) whose input end is connected to the positive and negative ends of the second DC filter circuit (3) and whose output end is connected to the dual-core general control unit (7), a second three-phase inverter circuit (4) whose AC side is connected to the secondary winding of the three-phase transformer (8), a second inverter output current detection circuit (6) whose input end is connected to the AC side of the second three-phase inverter circuit (4) and whose output end is connected to the dual-core general control unit (7), a bypass circuit breaker (9) connected in parallel to the corresponding winding of the primary side of the three-phase transformer (8), and an AC voltage detection circuit (10) whose input end is connected to the three-phase power input end (1) and whose output end is connected to the dual-core general control unit (7); The AC voltage stabilization system further comprises a human-machine interaction interface (20) connected to the control unit via a signal bus; the first DC voltage detection circuit (19) and the second DC voltage detection circuit (5) are both composed of a DC voltage sensor and a signal conditioning circuit.

2. The AC voltage stabilization system with reactive power compensation according to claim 1, characterized in that: The first DC filter circuit (17) and the second DC filter circuit (3) are composed of a plurality of electrolytic capacitors or film capacitors connected in series and in parallel.

3. The AC voltage stabilization system with reactive power compensation according to claim 2, characterized in that: The dual-core general control unit includes a main control chip of model TMS320F28377 that shares common data.

4. The AC voltage stabilization system with reactive power compensation according to claim 1, characterized in that: The first inverter output current detection circuit (18), the second inverter output current detection circuit (6), and the load current detection circuit (11) are each composed of three current sensors and three signal conditioning circuits, and one current sensor is connected to one corresponding signal conditioning circuit.

5. The AC voltage stabilization system with reactive power compensation according to claim 1, characterized in that: The AC voltage detection circuit (10) is composed of three AC voltage sensors and three signal conditioning circuits; one AC voltage sensor is connected to one signal conditioning circuit.

6. An AC voltage stabilization system with reactive power compensation according to any one of claims 3 to 5, characterized in that: The signal conditioning circuit comprises a sampling filter circuit (22), a differential amplifier circuit (23), a current limiting filter circuit (24), and a clamp circuit (25) which are connected in sequence, and a signal is input from the sampling filter circuit (22) and output from the clamp circuit (25).

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