CN103698641A - Energy feedback type electric equipment testing system and method - Google Patents

Abstract

The invention relates to an energy feedback type electrical equipment testing system and an energy feedback type electrical equipment testing method. The testing system includes an electronic load, a controller, an electrical equipment, and a current and voltage sampling module. The electronic load is connected in series to a three-phase Electrically, the electrical equipment and the current and voltage sampling module are connected to the input terminals of the electronic load in sequence, the electrical equipment is connected to the three-phase power in parallel, and the controller is respectively connected to the current and voltage sampling module and the electronic load. The electronic load includes a A rectifier module for generating current and an inverter module for energy feedback; the present invention can truly simulate various limit conditions in the power grid through electronic loads, and is used to detect various reactive currents and active power of electrical equipment in the power grid. The influence of current and harmonic current on itself, through detection, is conducive to the optimization and upgrading of electrical equipment itself on the one hand, and on the other hand, it also avoids the disadvantages caused by the open-loop test method in the prior art.

Description

Energy feedback type electrical equipment testing system and method

technical field

The invention relates to the technical field of power quality testing in power transmission and distribution systems, in particular to an energy feedback type electric equipment testing system and method.

Background technique

At present, a large number of electrical appliances, household electrical appliances and nonlinear loads are connected to the power grid, causing a large amount of reactive current and harmonic current to be injected into the power grid. The working environment of the power grid is intricate, interacting and interfering. These effects not only cause a great increase in power grid transmission loss, but also make various electrical equipment work abnormally. On the other hand, the existing electrical equipment can only use simulation or reasoning to test electrical equipment in harmonic current , The working state in the reactive current environment, but how much reactive current and harmonic current will cause damage to the electrical equipment in practice, there is no way to study it.

In the prior art, there are also electronic loads used to simulate power grid quality and test electrical equipment. This type of electronic load mainly adopts an open-loop test method, that is, a single variable is used. Other parameters are rated. Some properties of electrical equipment or the secondary circuit of the equipment are tested, for example, only the content of harmonic current in the system is tested, or only the three-phase unbalance degree in the system is tested, etc. In the above tests, the harmonic current and the three-phase Phase unbalance is a single variable, while other power factors are within the rated range. However, in power transmission and distribution systems, factors such as harmonic current, power factor, and three-phase current imbalance often coexist. The detection and monitoring results of the above methods are too ideal, and the detected data are difficult to meet the actual needs of the power distribution system. It is more difficult to truly simulate the live operating environment of the power distribution system.

Contents of the invention

The technical problem to be solved by the present invention is to aim at the above-mentioned problems existing in the prior art, and to provide an energy-feedback utility model for simulating various limit conditions in the power grid and having functions of reactive current, active current and harmonic current feedback. Electrical equipment testing system and method.

For solving the above problem, a kind of technical scheme of the present invention is:

An energy feedback type electrical equipment test system, the test system includes an electronic load, a controller, an electrical equipment, and a current and voltage sampling module for collecting the current and voltage at the input terminal of the electronic load, and the electronic load is connected in series to the three-phase power Above, the electrical equipment and the current and voltage sampling module are connected to the input end of the electronic load in sequence, the electrical equipment is connected to the three-phase power in parallel, and the controller is respectively connected to the current and voltage sampling module and the electronic load; the electronic load It includes a rectifier module for generating current and an inverter module for energy feedback, the rectifier module is connected to the inverter module, and both the rectifier module and the inverter module are provided with control terminals for connecting to the controller; It is equipped with an active current rectification unit for generating active current, a reactive current rectification unit for generating reactive current, and a harmonic current rectification unit for generating harmonic current. The inverter module is equipped with a rectification unit for absorbing active current Active current inverter unit for generating active current, reactive current inverter unit for absorbing reactive current generated by reactive current rectification unit, and harmonic current inverter unit for absorbing harmonic current generated by harmonic current rectification unit The active current inverter unit is connected with the active current rectification unit, the reactive current inverter unit is connected with the reactive current rectification unit, and the harmonic current inverter unit is connected with the harmonic current rectification unit.

Preferably, the active current rectification unit includes a three-phase four-wire switch S1, a four-phase reactor L1 and a rectifier MK1 connected in sequence, the three-phase four-wire switch S1 is respectively connected to the three-phase line and the neutral line, the active The current inverter unit includes a three-phase four-wire switch S2 connected in sequence, a four-phase reactor L2 and a rectifier MK2, the three-phase four-wire switch S2 is respectively connected to the three-phase line and the neutral line, and the rectifier MK1 is connected to the DC side of the rectifier MK2 share a capacitor C, the rectifier MK1 and the rectifier MK2 are voltage-type half-bridge PWM rectifiers; the reactive current rectifying unit and the harmonic current rectifying unit share the circuit of the active current rectifying unit, and the reactive current inverter unit The circuit of the active current inverter unit is shared with the harmonic current inverter unit.

Preferably, the rectifiers MK1 and MK2 each include an A-phase rectifier, a B-phase rectifier, a C-phase rectifier, and an N-phase rectifier, and each phase rectifier includes two bridge arms, and each bridge arm includes an insulated gate bipolar The transistor and the rectifying diode connected in antiparallel between the emitter and the collector of the insulated gate bipolar transistor, the gate of each insulated gate bipolar transistor is a control terminal.

Compared with the prior art, the energy feedback type electrical equipment testing system of the present invention can truly simulate various limit conditions in the power grid through the electronic load, and the electronic load can simulate the active current, Reactive current, harmonic current and three-phase unbalance degree, the active current, reactive current and harmonic current generated by the rectifier module are recovered through the inverter module, and the three-phase unbalance degree is compensated to avoid active current , reactive current and harmonic current are connected to the power grid, the energy recovery rate is high, energy saving and environmental protection; at the same time, it can also simulate various other extreme conditions in the power grid to detect the impact of various conditions in the power grid on electrical equipment Impact and conduct aging tests to detect the influence of various reactive currents, active currents and harmonic currents on the electrical equipment in the power grid. Through testing, on the one hand, it is conducive to the optimization and upgrading of the electrical equipment itself, on the other hand It also avoids the disadvantages caused by using the open-loop test method in the prior art; at the same time, the electronic load recovers and utilizes the energy of the active current, reactive current and harmonic current generated by the rectifier module, which is energy-saving and environmentally friendly.

An energy feedback type electrical equipment testing method, the testing method is based on the electrical equipment testing system mentioned above, and the testing method includes the following steps:

a) The electrical equipment test system is connected to the power grid, and the electrical equipment works normally;

b) The current and voltage sampling module collects the current and voltage at the input terminal of the electronic load in real time, and inputs the collected current and voltage to the controller for processing, and the controller outputs control signals to the electronic load;

c) Under the control of the controller, the active current rectification unit, reactive current rectification unit and harmonic current rectification unit in the rectification module respectively generate active current, reactive current and harmonic current for testing electrical equipment and input them In the electrical equipment, test the working status of the electrical equipment under different electrical active currents, reactive currents and harmonic currents;

d) Under the control of the controller, the inverter module outputs the corresponding current and harmonic current according to the active current, reactive current and harmonic current generated in the rectifier module to offset the active current, reactive current and harmonic current generated by the rectifier module The harmonic current is fed back to the power grid through the three-phase electric cycle after inversion.

Preferably, the step d specifically includes: under the control of the controller, the active current inverter unit generates reverse active current, the reactive current inverter unit generates reverse reactive current, and the harmonic current inverter unit generates The reverse harmonic current makes the active current generated by the active current rectification unit cancel the reverse active current, the reactive current generated by the reactive current rectification unit cancels the reverse reactive current, and the harmonic current rectification unit The generated harmonic current cancels out the reverse harmonic current.

Compared with the prior art, the electrical equipment testing method of the present invention can truly simulate various limit conditions in the power grid through electronic loads, so as to detect the harmony of various reactive currents and active currents encountered by the electrical equipment in the power grid. The impact of the wave current on itself, through detection, on the one hand, is beneficial to the optimization and upgrading of the electrical equipment itself, and on the other hand, it also avoids the disadvantages caused by the open-loop test method in the prior art; at the same time, the electronic load produces Active current, reactive current and harmonic current for energy recovery and utilization, energy saving and environmental protection.

Description of drawings

Fig. 1 is a block diagram of the circuit principle of the energy feedback type electrical equipment testing system of the present invention.

Fig. 2 is a block diagram of the circuit principle of the electronic load in the energy feedback type electrical equipment testing system of the present invention.

Fig. 3 is a circuit diagram of an electronic load in the energy feedback type electrical equipment testing system of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the protection scope of the present invention is not limited thereto.

Referring to Fig. 1, the energy feedback type electrical equipment testing system of the present invention comprises electronic load, controller, electrical equipment and the current and voltage sampling module that is used to collect the input terminal current and voltage of electronic load, and electronic load is connected in series in three-phase power supply. Above, the electrical equipment and the current and voltage sampling module are connected to the input terminal of the electronic load in sequence, the electrical equipment is connected to the three-phase power in parallel, and the controller is connected to the current and voltage sampling module and the electronic load respectively. The electrical equipment test system is used to study the influence of active current, reactive current and harmonic current on electrical equipment, and to simulate the working characteristics of electrical equipment under various extreme conditions through electronic loads. The electrical equipment in the electrical equipment test system can also be replaced with various power products, and the electrical equipment test system can be used to perform aging tests on power products, and can simulate loads with various characteristics: such as inductive loads, capacitive loads, resistive loads, etc. loads and various non-linear loads.

Referring to Figure 2, the electronic load includes a rectifier module and an inverter module, the rectifier module is connected to the inverter module, the rectifier module and the inverter module are provided with a control terminal for connecting with the controller, and the controller is used to control the rectifier module and the inverter module The output of the module. The rectifier module is used to generate various harmonic currents, three-phase load unbalance load, active current and reactive current, etc. The inverter module is used to absorb various currents generated by the rectifier module, and the inverter module converts 80 More than 100% of electric energy can be recycled.

The rectification module is provided with an active current rectification unit for generating active current, a reactive current rectification unit for generating reactive current, and a harmonic current rectification unit for generating harmonic current. The harmonic current order and harmonic content output by the harmonic current rectification unit are continuously adjustable, and the load harmonic range is 1-25, which can study the mechanism and control measures of the influence of harmonics on electrical equipment. The inverter module is equipped with an active current inverter unit, a reactive current inverter unit and a harmonic current inverter unit. The active current inverter unit is used to absorb the active current generated by the active current rectification unit, and the reactive current inverter unit is used for To absorb the reactive current generated by the reactive current rectification unit, the harmonic current inverter unit is used to absorb the harmonic current generated by the harmonic current rectification unit, the active current inverter unit is connected to the active current rectification unit, and the reactive current inverter The unit is connected with the reactive current rectification unit, and the harmonic current inverter unit is connected with the harmonic current rectification unit.

Referring to Figure 3, the active current rectification unit includes a three-phase four-wire switch S1, a four-phase reactor L1 and a rectifier MK1 connected in sequence. connected, the voltages on each phase are marked as Ua, Ub, Uc and Un in Figure 3, and the four-phase reactor L1 is an additional reactor on the AC side, which balances the voltage and supports reactive power in the circuit of the rectifier MK1 The role of power. The active current inverter unit includes a three-phase four-wire switch S2, a four-phase reactor L2 and a rectifier MK2 connected in sequence. The three-phase four-wire switch S2 is respectively connected to the three-phase line a', b', c' and neutral Line n' is connected, and the voltages on each phase are respectively marked as Ua', Ub', Uc' and Un' in Figure 3. The DC side of rectifier MK1 and rectifier MK2 share a capacitor C, and capacitor C is the rectifier MK1 and rectifier MK2 The supporting capacitor between them, the rectifier MK1 and the rectifier MK2 are voltage-type half-bridge PWM rectifiers. Rectifier MK1 includes A-phase rectifier K01, B-phase rectifier K02, C-phase rectifier K03, and N-phase rectifier K04. Rectifier MK2 includes A-phase rectifier K11, B-phase rectifier K12, C-phase rectifier K13, and N-phase rectifier K14. The rectifiers of each phase are respectively Including two bridge arms, each bridge arm includes an insulated gate bipolar transistor IGBT and a rectifier diode connected in reverse parallel between the emitter and collector of the insulated gate bipolar transistor, each insulated gate bipolar transistor The gate of the polar transistor is the control terminal.

Among them, the reactive current rectification unit and the harmonic current rectification unit share the circuit of the active current rectification unit, that is, the circuit of the active current rectification unit completes the rectification of active current, reactive current and harmonic current at the same time, and the reactive current inverter unit and The harmonic current inverter unit shares the circuit of the active current inverter unit, that is, the circuit of the active current inverter unit completes the inversion of active current, reactive current and harmonic current at the same time.

The electronic load is connected to the system with three-phase four-wire, and the electrical equipment can also be installed in a space that can control temperature and humidity for loss characteristic testing under different temperature and humidity conditions. When the energy feedback type electrical equipment testing system of the present invention is working, the controller monitors the grid current and voltage signals in real time, converts the sampled analog voltage signals into digital signals, and processes the digital signals sent by the controller. Generate a control signal to the electronic load, control the rectifier module to generate active current, reactive current and harmonic current, and control each insulated gate bipolar transistor IGBT in the form of a pulse width modulation signal. During the operation of the electronic load, the AC input terminals Ua and Ub of the bridge arm will generate a PWM wave Uab. The PWM wave Uab contains a fundamental wave component with the same frequency and amplitude proportional to the input sinusoidal signal wave, and is related to the triangular carrier wave. high frequency harmonics. The PWM wave Uab and the grid voltage Us act together on the four-phase reactor L1 to generate a sinusoidal input current Is. When the grid voltage Us is constant, the amplitude and phase of the sinusoidal input current Is are only determined by the PWM wave Uab. By controlling the amplitude and phase of the voltage Uab on the AC side of the rectifier module, the input current Is of the required magnitude and phase can be obtained. .

When the sinusoidal input current Is is in phase with the grid voltage Us, the circuit operates as a rectifier, otherwise, the circuit operates as an inverter. Rectifier MK1 and rectifier MK2 have the AC/DC conversion function of energy bidirectional transmission function. When the rectifier absorbs energy from the grid, the rectifier operates in the rectification working state, and when the PWM rectifier transmits electric energy to the grid, it operates in active inverter working status. In the present invention, as an electronic load, the rectifier MK1 mainly works in the rectifier mode, and realizes various current waveforms according to requirements, including the generation of active current, reactive current, harmonic current and the like. The rectifier MK2 mainly works in the active inverter mode, and its main job is to feed back the energy absorbed by the rectifier MK1 to the grid, and at the same time, filter out the harmonic current entering the grid, so as to realize energy recycling.

The inverter module of the present invention can perform active filtering and reactive power compensation on the harmonic current and reactive power generated by the rectifier module and recover them, and then return the recovered energy to the power grid after inversion. After testing the energy recovery of the entire system The efficiency is above 95%, the power factor is ≥0.99, and the harmonic distortion rate of the current is low.

The energy feedback type electrical equipment testing method of the present invention is based on the above-mentioned electrical equipment testing system, and includes the following steps:

a) The electrical equipment test system is connected to the power grid, and the electrical equipment works normally;

b) The current and voltage sampling module collects the current and voltage at the input terminal of the electronic load in real time, and inputs the collected current and voltage to the controller for processing, and the controller outputs control signals to the electronic load;

c) Under the control of the controller, the active current rectification unit, reactive current rectification unit and harmonic current rectification unit in the rectification module respectively generate active current, reactive current and harmonic current for testing electrical equipment and input them In the electrical equipment, test the working status of the electrical equipment under different active currents, reactive currents and harmonic currents;

d) Under the control of the controller, the inverter module outputs the corresponding current according to the active current, reactive current and harmonic current generated in the rectifier module to offset the active current, reactive current and harmonic current generated by the rectifier module, The filtered three-phase electric cycle is fed back to the grid. Specifically, under the control of the controller, the active current inverter unit generates reverse active current, the reactive current inverter unit generates reverse reactive current, and the harmonic current inverter unit generates reverse harmonic current, so that The active current generated by the active current rectifier unit cancels the reverse active current, the reactive current generated by the reactive current rectifier unit cancels the reverse reactive current, and the harmonic current generated by the harmonic current rectifier unit counteracts the reverse The harmonic current cancels out.

In the above description, all the technical means in the prior art are used for those not specifically stated.

Claims (5)

1. An energy feedback type electric device test system, characterized in that the test system includes an electronic load, a controller, an electric device and a current and voltage sampling module for collecting the input terminal current and voltage of the electronic load, and the electronic load Connected in series to the three-phase power, the electrical equipment and the current and voltage sampling module are connected to the input terminal of the electronic load in sequence, the electrical equipment is connected to the three-phase power in parallel, and the controller is connected with the current and voltage sampling module and the electronic load respectively connected; the electronic load includes a rectifier module for generating current and an inverter module for energy feedback, the rectifier module is connected to the inverter module, and both the rectifier module and the inverter module are provided with control terminals for connecting to the controller ; The rectification module is provided with an active current rectification unit for generating active current, a reactive current rectification unit for generating reactive current and a harmonic current rectification unit for generating harmonic current, and the inverter module is equipped with a The active current inverter unit for absorbing the active current generated by the active current rectification unit, the reactive current inverter unit for absorbing the reactive current generated by the reactive current rectification unit and the harmonic wave generated by the harmonic current rectification unit The current harmonic current inverter unit, the active current inverter unit is connected with the active current rectification unit, the reactive current inverter unit is connected with the reactive current rectification unit, and the harmonic current inverter unit is connected with the harmonic current rectification unit. 2. The energy feedback type electrical equipment testing system according to claim 1, wherein the active current rectification unit comprises a three-phase four-wire switch S1 connected in sequence, a four-phase reactor L1 and a rectifier MK1, three The phase four-wire switch S1 is connected to the three-phase line and the neutral line respectively, and the active current inverter unit includes a three-phase four-wire switch S2 connected in sequence, a four-phase reactor L2 and a rectifier MK2, and the three-phase four-wire switch S2 Respectively connected to the three-phase line and the neutral line, the rectifier MK1 and the rectifier MK2 share a capacitor C on the DC side, the rectifier MK1 and the rectifier MK2 are voltage-type half-bridge PWM rectifiers; the reactive current rectification unit and the harmonic The current rectification unit shares the circuit of the active current rectification unit, and the reactive current inverter unit and the harmonic current inverter unit share the circuit of the active current inverter unit. 3. The energy feedback type electrical equipment testing system according to claim 2, wherein the rectifier MK1 and the rectifier MK2 all include a phase A rectifier, a B phase rectifier, a C phase rectifier and an N phase rectifier, each phase rectifier Including two bridge arms, each bridge arm includes an insulated gate bipolar transistor and a rectifier diode connected in reverse parallel between the emitter and collector of the insulated gate bipolar transistor, each insulated gate bipolar transistor The gate of the polar transistor is the control terminal. 4. An energy feedback type electrical equipment testing method, characterized in that the testing method is based on the energy feedback type electrical equipment testing system according to any one of claims 1-3, and the testing method comprises the following steps: a) The energy feedback type electrical equipment test system is connected to the power grid, and the electrical equipment works normally; b) The current and voltage sampling module collects the current and voltage at the input terminal of the electronic load in real time, and inputs the collected current and voltage to the controller for processing, and the controller outputs control signals to the electronic load; c) Under the control of the controller, the active current rectification unit, reactive current rectification unit and harmonic current rectification unit in the rectification module respectively generate active current, reactive current and harmonic current for testing electrical equipment and input them In the electrical equipment, test the working status of the electrical equipment under different active currents, reactive currents and harmonic currents; d) Under the control of the controller, the inverter module outputs the corresponding current according to the active current, reactive current and harmonic current generated in the rectifier module to offset the active current, reactive current and harmonic current generated by the rectifier module, The three-phase electric cycle after inversion is fed back to the grid. 5. The energy feedback type electrical equipment testing method according to claim 4, wherein the step d is specifically: under the control of the controller, the active current inverter unit generates a reverse active current, reactive power The current inverter unit generates a reverse reactive current, and the harmonic current inverter unit generates a reverse harmonic current, so that the active current generated by the active current rectification unit offsets the reverse active current, and the reactive current rectification unit generates The reactive current of the rectifier cancels the reverse reactive current, and the harmonic current generated by the harmonic current rectification unit cancels the reverse harmonic current.

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