GB/T 43534-2023 in English

1. Background and significance of the standard

GB/T 43534-2023 "Design and test methods for AC side impedance of voltage source converters for high-voltage direct current transmission" is a key technical standard for flexible direct current transmission systems, which aims to standardize the design and test requirements of the AC side impedance of voltage source converters (VSC).

With the increase in the proportion of renewable energy access, high-voltage direct current transmission (HVDC) systems face complex grid environments and higher stability requirements. The formulation of this standard fills the gap in the study of impedance characteristics of voltage source converters under complex grid conditions and provides an important basis for engineering design.

2. Comparative analysis of standard frameworks

Note: The above table shows the comparison between GB/T 43534—2023 and related standards in terms of scope of application, core content and technical indicators, highlighting its industry-leading nature.

3. Analysis of key technologies

3.1 Factors affecting impedance

VSCThe AC side impedance is affected by many factors, including:

• Primary system equipment: connection transformer, bridge arm reactor, etc.
• Control system links: sampling, signal processing, power/voltage control, etc.
• Control link delay: sensor, analog-to-digital conversion unit, communication module, etc.

Among them, the control link delay is required to be ≤200 μs, which needs to be strictly controlled in actual projects.

3.2 Impedance design requirements

The standard specifies the following key indicators:

• The impedance ratio ($Z_s/Z_{VSC}$) must meet the Nyquist stability criterion;
• The AC side impedance is in the range of 200 Hz to 5000 Hz, and the ideal phase is -90° to 90°;
• The test data must cover both positive and negative sequence impedances and be presented in a list.

In addition, it is recommended to ensure data reliability by mutual verification through theoretical calculation, electromagnetic transient simulation and hardware-in-the-loop (HIL) testing during the design phase.

4. Implementation Suggestions

4.1 Precautions in Engineering Applications

• During the functional verification test phase, the delay of the control device needs to be tested, and the control strategy needs to be optimized in combination with the real-time simulation system;
• During the subsystem link delay test, the performance of modules such as the primary sensor, converter control unit and valve base control device should be measured separately.

4.2 Test Method Optimization

It is recommended to use an oscilloscope with a high sampling rate (≥1 GSa/s) in the hardware-in-the-loop test to ensure measurement accuracy. At the same time, according to the grid impedance data under different operating modes, the test parameters are dynamically adjusted to improve the test efficiency.