EMC Alternative Test Method for High Power Photovoltaic Inverter_Century Wisdom (Suzhou) Testing Technology Co., Ltd

English

Home page

Technical column

CASES

EMC Alternative Test Method for High Power Photovoltaic Inverter

Release time:

2023-09-12 15:49

Source:

　　1. Preface

At present, the major domestic PV inverter manufacturers have launched a higher power level of inverter products. In terms of centralized inverters: sunlight power supply, Shangneng Electric, etc. have introduced high-power products with rated power of 3125KW or 3300KW. In terms of string inverters: Huawei, Sunshine Power, Jinlang Technology, Goodway and other mainstream manufacturers have also introduced 150KW-320KW high-power string products. The improvement of the power level of the inverter, on the one hand, is to adapt to the improvement of the power of the photovoltaic module and the increasing construction scale of the photovoltaic power station. At the same time, it can also effectively reduce the single-watt cost of the inverter, thereby reducing the overall cost of the photovoltaic power station.

However, the EMC immunity and conducted emission test, because the high current level of the high-power photovoltaic inverter exceeds the rated current capacity of the EMC test equipment, it is technically impossible to use regular test method.

This article mainly introduces the maximum rated current equipment that can be provided by current mainstream EMC suppliers and provides alternative test methods for high-power photovoltaic inverter product standards (based on standard IEC62920:2017-EMC requirements and test methods for power conversion equipment of photovoltaic power generation system).

　　2. EMC test supplier maximum current equipment introduction

At present, the mainstream foreign EMC immunity test equipment suppliers are EMTEST and TESEQ, which belong to the United States AMETEK. Foreign mainstream conducted emission test equipment suppliers are schwarzbeck. The following is a summary of the maximum current capacity test equipment that foreign mainstream EMC suppliers can provide in different test projects.

2.1 surge and fast transient burst projects

Fig. 1 Integrated immunity test system

At present, the mainstream suppliers of surge and fast transient pulse group projects can provide three-phase coupling decoupling network with a maximum current of 200A.

Fig. 1 is an integrated immunity test system of EMTEST supplier. generator host model: compact NX5 bsp-1-400-16 and three-phase coupling decoupling network model: coupling NX5 bs-3-690-200.3. three-phase coupling decoupling network can withstand maximum voltage: 3 x 690 VAC /1000 VDC, maximum current: 200A.

Conducted Immunity to 2.2 RF Field

Fig. 2 EMTEST supplier provides decoupling network capable of withstanding maximum current coupling for conduction immunity project caused by radio frequency field, model: CDN M5-100-750V, withstanding maximum current 100A and maximum voltage 750V v.

Figure 2 Coupling and decoupling network CDN M5-100-750V

2.3 conducted emission items

Figure 3 Artificial power network NNLK8129

Fig. 3 provides an artificial power supply network that can withstand the maximum current for the schwarzbeck supplier's conducted launch project, model: NNLK8129, maximum voltage: 400 VAC /800 VDC, and maximum current: 4x 200 A.

　　3. High-power photovoltaic inverter EMC alternative test method (according to standard IEC62920:2017)

3.1 Fast Transient Pulse Group Project

If there is no technically suitable coupling decoupling network for the AC mains port of the high-power PV inverter due to the limitation of the rated current capacity of the pulse group coupling decoupling network, the coupling decoupling network can be connected in parallel with the AC mains port, as shown in Figure D.1, using a 33 nF capacitor for direct injection. The isolation transformer can decouple the differential mode pulse signal, and the common mode choke can decouple the common mode pulse signal

Fig. D.1 Substitution of Pulse Group Test

Alternative Methods for 3.2 Surge Testing

If it is technically impossible to provide a suitable coupling-decoupling network for the AC main power port of the high-power photovoltaic inverter due to the limitation of the rated current capacity of the surge coupling-decoupling network, the coupling-decoupling network can be connected in parallel with the AC mains port.

The isolation transformer can decouple the differential mode surge signal, and the common mode choke can decouple the common mode surge signal.

Figure D.2 Surge Test Alternatives

Alternative Test Method for Conducted Immunity Caused by 3.3 Radio Frequency Field

IEC 61000 -4-6 stipulates that if the product committee decides that a coupling decoupling device is more suitable for connecting to the cable of a specific product series, this choice (reasonable on a technical basis) takes precedence. The alternative method is shown in D.3. If the CDN described in Annex D of IEC 61000 -4-6 cannot be used as a decoupling device technically due to the high power of the AC power port of the inverter, the CDN can be connected in parallel to inject conducted interference into the port as a coupling device. CDN as a coupling device, common mode choke and isolation transformer as a decoupling device for AC mains.

Figure D.3-Example of AC Power Port Testing Using Clamp Injection

3.4 conducted emission (using an artificial network as a voltage probe)

If, due to the limitation of the rated current capacity of the artificial network, there is technically no suitable artificial network that can perform series conducted emission measurements on the power port of the photovoltaic inverter, the artificial network can be used as a voltage probe and the artificial network can be connected in parallel to the power port. Figure D.4 shows an example of a cable arrangement to measure the conducted emission of the power port, where the artificial network is connected in parallel to the power port. Each power port shall be connected to each power source by a decoupling network. The inductance value of the decoupling network at the AC power port should be between 30 μH and 50 μH, and the inductance value at the DC power port should be between 90 μH and 150 μH. The decoupling network is realized by the common mode choke and isolation transformer of the AC power port, and the common mode choke of the DC power port,

Figure D.4-Alternative test method for conducted emission measurements using an artificial network as a voltage probe

Hope that through the introduction of this article, so that we can master the high-power photovoltaic inverter alternative test method.

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