Monitoring network quality and required efficiency of EV charging stations

Thus, as mentioned above, there are two reasons for measuring on NS:

1. Verification that the station is not affected by network disturbances in the power supply (i.e. the input parameters to the NS are monitored), thus ensuring the output to the BEV is of the required quality.
2. Verification of the correct functionality of the station itself according to the given specifications.

During the installation of the NS, it is important for the operator to verify that the quality of the power supplied is within the tolerances specified in the relevant standards. The result of the measurement can therefore be, among other things, proof of the quality or otherwise of the power supplied, as a result of which any problems during charging of the BEV can be eliminated. At the same time, it is also possible to identify a possible malfunction of the NS itself.
The figure below shows a practical implementation of measuring the power quality of the NS directly in the field. The measurements are taken in real operation while the BEV is charging (with the NS acting as the load) and the power quality analyzer is set up to record the measurements at the same time. Connections are made simultaneously on both the input side to the NS (i.e. AC measurements) and on the output DC side from the station. Depending on the state of charge (SOC) and vehicle type, the measurement time can vary from approximately 15 minutes to one hour.

These parameters vary depending on which of the above two measurement purposes is the focus of attention:

1. Verification of the quality of the power supply from the utility grid:

• Basic power quality parameters such as voltage dips, voltage swells and voltage interruptions.
• harmonic and total harmonic distortion (THD)
• power factor
• frequency fluctuation

2. Verification of NS specifications:

• AC mains voltage, current and power
• converted DC voltage, current and power
• rectification efficiency (= NS efficiency)
• accuracy of the NS calculation system for determining energy consumption

Of course, several parameters may be monitored during the check, depending on the specific normative regulations of the country where the NS is operated and the requirements of the operator and manufacturer of the NS.

For the application described, HIOKI recommends the PQ3198 power quality analyzer because of its compatibility with relevant standards, its ability to take two independent (AC and DC) measurements simultaneously, its ability to measure harmonics, its easily configurable interface, and the wide range of current sensors available.

1. Compliance with standards

The PQ3198 complies with the requirements of IEC 61000-4-30 Ed. 3 Class A. The standard classifies the measurement methods in AC power systems, as well as the capabilities of the measuring instruments, into two classes, A and S. Because Class A provides a more reliable measurement of power quality, the PQ3198 is also a more reliable meter for resolving potential power supply disputes and ensuring compliance with the standards. Thus, a Class A certified power quality analyzer such as the PQ3198 can provide reliable measurement results for monitoring the required power quality parameters.

2. Two circuit measurement

The fourth voltage channel of the PQ3198 analyzer is isolated from the first three voltage channels, allowing the instrument to safely measure power quality and efficiency in two separate circuits. The instrument allows you to verify the quality of the input (AC) and output (DC) of the NS, thereby simultaneously measuring the power quality and efficiency between the input and output.

3. Harmonics and THD measurements

In addition to measuring harmonics and THD up to the 50th order, the PQ3198 is also capable of capturing the supraharmonic component (up to 80 kHz). By combining analysis and reporting software (HIOKI PQ One), the FFT analysis of the supraharmonic component can be performed and a measurement report can be generated in an instant.

4. Easy setup

The PQ3198 offers predefined measurement scenarios to facilitate quick configuration of the instrument before starting the actual measurement. Presets such as EN 50160 allow you to evaluate whether the data conforms to the EN 50160 standard by analyzing it and automatically generating an assessment based on voltage fluctuations during a given time period (exactly as required by the standard). Of course, you can also create your own settings for the measurement conditions and save these in the analyzer's memory - and reuse these saved settings at other stations. This ensures exactly the same measurement conditions within, for example, one operator (and manufacturer) of a particular NS.

5. Wide range of current sensors

The flexible CT7045 is ideal for measuring current in confined spaces, for example just inside an NS, and its three ranges (50, 500 and 5000 A) make it the most suitable for measuring currents over a really wide range. For DC current, we would recommend the CT7736 AC/DC sensor (AC/DC 600 A). Since no mains adapter is needed to power our flexible and AC/DC sensors, the measurement is much smoother than other manufacturers' current sensors and also requires less cabling.

Ensuring future mobility with a quality infrastructure for BEVs can only start with a quality power supply at the charging station. The HIOKI Power Quality Analyzer will help you better identify potential problems at their source and at the core of the entire infrastructure, which is undoubtedly the charging station.

For more information about the PQ3198 Power Quality Analyzer , please click here or contact us directly.