Introduction to EMC Testing of Power Conversion Equipment (PCE) for Photovoltaic (PV) Power Systems_Century Wisdom (Suzhou) Testing Technology Co., Ltd

English

Home page

Technical column

CASES

Introduction to EMC Testing of Power Conversion Equipment (PCE) for Photovoltaic (PV) Power Systems

Release time:

2022-08-23 00:00

Source:

　　The IEC 62920:2017 standard specifies the electromagnetic compatibility (EMC) requirements for power conversion equipment (PCE) used in photovoltaic (PV) power systems.

　　The PCE specified in this standard can be grid-connected type, called grid-connected power converter (GCPC), or it can be off-grid. It can consist of one or more arrays of various photovoltaic modules and can be used with batteries or other forms of energy storage. This includes not only PCEs connected to low-voltage grids or other low-voltage AC power supply equipment, but also PCEs connected to medium-voltage or high-voltage grids. Requirements for PCEs connected to medium-voltage or high-voltage AC grids are specified in this document.

　　1. General test requirements

　　1.1, Classification of Power Conversion Equipment (PCE)

　　In keeping with the basic, general and product family standards, the document defines two classes of equipment, Class A and Class B, based on environmental categories.

　　Among them: Class A PCE is suitable for non-residential environments, and Class A PCE meets Class A requirements;

　　Class B PCE is suitable for residential environments, and Class B PCE meets Class B requirements.

　　Fig. 1 is a diagram showing an example of the installation environment of power conversion equipment (PCE).

Figure 1 - Diagram of an example installation environment for power conversion equipment (PCE)

　　1.2, Working mode during the test

　　A: Standby Mode: The PCE is connected to the AC source and powered, but does not generate or supply power to the AC source or electrical energy storage devices. The voltage level at the DC power port does not need to be within the rated operating range.

　　B: Mode of operation in which power is supplied to the AC grid and/or discharged from electrical energy storage: the PCE is to operate at the rated operating point.

　　C: Operating mode for charging the storage device from photovoltaic modules and/or AC grid: PCE should operate at the rated operating point.

　　2. Immunity requirements

　　2.1, the immunity requirements are shown in Figure 2~Figure 5.

Figure 2 - Class A PCE immunity requirements

Figure 3 - Class B PCE immunity requirements

Figure 4 - Class A PCE voltage dips and short interruption requirements

Figure 5 - Class B PCE Voltage Dips and Short Interruption Requirements

　　2.2, the performance criterion is shown in Figure 6.

Figure 6 - Immunity Test Performance Criteria

　　3. Launch requirements

　　3.1, low frequency emission

　　The low-frequency emission test is only performed on PCE AC mains ports connected to the low-voltage grid, not applicable to medium- and high-voltage PCEs.

　　Figure 7 is a flowchart of the evaluation and test procedure for harmonics below 75A, and Figure 8 is a flowchart of the evaluation and test procedure for voltage fluctuations and flicker below 75A.

Figure 7- Flow chart of the evaluation and test procedure for harmonics below 75A

Figure 8 - Flow chart of evaluation and test procedures for voltage fluctuations and flicker below 75A

　　3.2, high frequency emission

　　3.2.1 Conducted emissions

　　3.2.1.1 AC port conducted emission limits, as shown in Figure 9 and Figure 10.

Figure 9 - AC Port Conducted Emissions Limits for Class A PCE

Figure 10 - AC Port Conducted Emissions Limits for Class B PCE

　　3.2.1.2 DC port conducted emission limits, as shown in Figure 11 and Figure 12.

Figure 11 - DC Port Conducted Emissions Limits for Class A PCE

Figure 12 - DC port conducted emission limits for Class B PCE

　　3.2.1.3 Conducted emission limits of wired network and signal and control ports, as shown in Figure 13 and Figure 14.

Figure 13 - Wired network and signal and control port conducted emission limits of Class A PCE

Figure 14 - Wired network and signal and control port conducted emission limits of Class B PCE

　　3.2.2 Radiated emissions

　　Figure 15 and Figure 16 respectively show the radiated emission limits of Class A and Class B PCEs.

Figure 15 - Radiated Emission Emission Limits for Class A PCE

　　Notice:

　　1. Only small and medium-sized PCEs can allow the measurement distance to be less than 10 meters (using a test distance of 3 meters or 5 meters).

　　2. Small PCE: The equipment (including its cables) is installed in an imaginary cylindrical test volume with a diameter of 1.5m and a height of 1.5m (to ground level), and measurements are performed at a measurement distance of 3m.

　　3. Medium-sized PCE: The equipment (including its cables) is installed in an imaginary cylindrical test volume with a diameter of 2m and a height of 2m (to the ground level), and the measurement is carried out at a measurement distance of 5m.

　　4. Select the corresponding limit value according to the actual power.

Figure 16 - Radiated emission emission limits for Class B PCE

　　Notice:

　　1,3m test distance is only suitable for small equipment.

　　2. The 5m test distance is only suitable for medium-sized equipment.

　　4. Reference test layout (take the wall-mounted PCE layout as an example)

　　4.1, Electrostatic discharge immunity test layout

　　The PCE shall be installed on an insulating support at a height of 0.8 m above the ground reference level, and a distance of not less than 0.8 m shall be maintained between the PCE and the test room wall and between the PCE and any other metal structure. The PCE should be grounded according to its installation manual and no additional ground connection is allowed. When testing in a laboratory, the ground datum shall be placed on the laboratory floor.

　　The horizontal coupling plane specified in IEC 61000-4-2 is not required if the supporting material of the wall-mounted PCE is placed on a metallic ground plane.

　　Figure 17 and Figure 18 are direct and indirect discharge layout diagrams respectively.

Figure 17 - Direct Discharge Arrangement

Figure 18 - Layout of Indirect Discharge

　　4.2, radiated immunity test layout

　　Figure 19 is a diagram of the radiation immunity layout of the wall-mounted PCE. The PCE shall be installed on an insulating support, and a wooden frame may be used to install the PCE, 0.8 m above the ground datum level, in the same manner as the manufacturer's installation instructions. Cables should be routed in accordance with the manufacturer's installation manual. Unless the manufacturer requires a specific cable, use unshielded and parallel conductors. If the manufacturer's installation specifications require power and signal cables and cables to peripheral equipment to be less than or equal to 3m in length, the required lengths shall be used. If the specified cable length is greater than 3m or if it is not specified, the minimum length of the cable exposed to the electromagnetic field is 1m. Excess cables should be decoupled with decoupling pliers.

Figure 19 - Arrangement diagram for radiated immunity

　　4.3, EFT immunity test arrangement

　　Figure 20 and Figure 21 are respectively CDN direct injection layout and capacitive coupling clamp injection layout.

　　Direct coupling of EFT/B disturbance voltages through the CDN is the preferred method of coupling to the power supply port, and if direct injection is not feasible, then a capacitive coupling clamp is used to apply the EFT disturbance pulses to the DC power supply port. When the PCE has two or more auxiliary power ports, the test voltage shall be applied to each of these ports in sequence.

　　The minimum distance between PCE and all other conductive structures (including test chamber walls) (except the ground reference plane) should be greater than 0.5m. The EFT generator and CDN should be connected to the ground reference plane.

　　All cables connected to the PCE shall be isolated from the ground reference plane by wooden or insulating materials with a thickness of (0.1 ± 0.01) m.

Figure 20 - EFT Layout (CDN Direct Injection)

Figure 21 - EFT Layout (Capacitive Coupled Clamp Injection)

　　4.4, Lightning strike/surge immunity test arrangement

　　Figure 22 is the layout of the AC port test, and Figure 23 is the layout of the DC port test.

Figure 22 - AC port test layout

Figure 23 - DC port test layout

　　4.5, Conducted Immunity Test Arrangement

　　The wall-mounted PC shall be tested on an insulating support at a height of (0.1 ± 0.05) m above the ground reference level. The PCE can be mounted using a wooden frame. All cables connected to the PCE should pass through with a thickness of at least 30mm. The minimum distance between the PCE and any metal object (except the test equipment) shall be 0.5m. It is recommended to connect all ports to CDN. If the PCE has two or more DC power ports, it is recommended to connect all DC power ports to the CDN. Figure 24 is the layout of the conducted immunity test

Figure 24 - Conducted Immunity Test Layout

　　4.6, Voltage dip and short interruption immunity test arrangement

　　The PCE shall be mounted on an insulating support, and a wooden frame may be used to mount the PCE in the same manner as the manufacturer's installation instructions. If the test generator does not have energy recovery, a resistive load is required between the PCE and the test generator to protect the generator from overcurrent. Figure 25 is a test layout for voltage dips and short interruptions.

Figure 25 - Layout of voltage dip and short interruption immunity test

　　4.7, Conducted emission test arrangement

　　Figure 26 is a layout diagram of the conducted emission test of the wall-mounted PCE with AC power in the laboratory. A resistive load is installed between the AMN and the AC power source.

Figure 26 - Test layout for conducted emission measurements of a wall-mounted PCE

　　Figure 27 is another configuration example of a test setup for a wall-mounted PCE. The laboratory AC power supply is connected to the DC power supply. Since the power does not flow into the laboratory AC mains, no resistive load is required. Installing a power transformer between the PCE and the power supply is optional. If power transformers are installed, they shall not affect the operation of the PCE and the type and size of the power transformer shall be recorded in the test report.

Figure 27 - Diagram of the test arrangement for conducted emission measurements of a wall-mounted PCE with power cycling

　　Fig. 28 is another configuration example of the wall-mounted PCE testing device. The AMN is directly connected to the AC mains through an EMI filter. A resistive load is optional and is used to prevent power from flowing into the AC mains.

Figure 28 - Test arrangement for conducted emission measurements of a wall-mounted PCE directly connected to an AC power supply

　　4.8, Radiation Emission Test Arrangement

　　Figure 29 is a layout diagram of the radiation emission test of the wall-mounted PCE. The PCE shall be tested on an insulating support at a height of (0.8±0.01) m from the ground reference plane. Place the insulating stand so that the center of the test volume is at the center of the turntable. The PCE can be mounted using a wooden frame.

Figure 29 - Radiated emission test layout for wall-mounted PCE

　　4.9 Harmonic current emission test arrangement

　　Measure the harmonic current generated by PCE according to the circuit described in Figure 30~Figure 33.

Figure 30- Single-phase two-wire PCE measurement circuit

Figure 31 - Single-phase three-wire PCE measurement circuit

Figure 32 - Three-phase three-wire PCE measurement circuit

Figure 33 - Three-phase four-wire PCE measurement circuit

　　4.10 Voltage fluctuation and flicker test arrangement

　　The voltage fluctuation and flicker at the AC main power port can be evaluated by a scintillation meter, the connection of the scintillation meter is shown in Figure 34~Figure 37.

Figure 34 - Single-phase two-wire PCE measurement circuit

Figure 35 Single-phase three-wire PCE measurement circuit

Figure 36 - Three-phase three-wire PCE measurement circuit

Figure 37- Three-phase four-wire PCE measurement circuit

　　5. Alternative test method for high power PCE

　　For the immunity and emission test of high-power PCE, it is technically impossible to use the test equipment normally, because the high current level of high-power PCE exceeds the rated current capacity of the test equipment. Some basic and product family standards provide alternative test methods.

　　5.1 Alternative to EFT immunity test

　　If a suitable coupling/decoupling network is not technically available at the AC mains port of the high-power PCE due to limitations in the rated current capacity of the coupling/decoupling network, direct injection with a 33nF capacitor can be used to decouple the coupling/decoupling The network is connected in parallel to the AC main power outlet, as shown in Figure 38. The transformer can decouple the differential mode test voltage, and the common mode inductor can decouple the common mode test voltage.

Figure 38 - Alternative method of EFT immunity test for high power PCE

　　5.2 Alternative method for lightning/surge immunity test

　　If a suitable coupling/decoupling network is not technically available at the AC mains port of the high-power PCE due to the limitation of the rated current capacity of the coupling/decoupling network, another coupling/decoupling network can be configured, as shown in Figure 39 .

Figure 39 - Alternative method of lightning/surge immunity test for high power PCE

　　5.3 Alternative method for conducted immunity test

　　If it is limited by the rated current capacity of the coupling/decoupling network, it can be configured according to Figure 40.

Figure 40 - Alternative method of conducted immunity test for high power PCE

　　5.4 Alternative method for conducted emission test

　　If due to the limitation of the rated current capacity of the artificial network, the conducted emission test cannot be carried out according to the standard requirements. The artificial power network can be used as a voltage probe and connected in parallel to the power port of the PCE for testing, as shown in Figure 41. Each power port should be connected to each power supply through a decoupling network. The inductance of the decoupling network should be 30 μH to 50 μH at the AC power port and should be greater than 90 μH to 150 μH at the DC power port.

Figure 41 - Alternative method of conducted emission test for high power PCE

Century Wisdom (Suzhou) Testing Technology Co., Ltd

www.300.cn nanjing SEO

Business License

全部

全部
产品管理
新闻资讯
介绍内容
企业网点
常见问题
企业视频
企业图册