With the rapid development of modern power grids, the large-scale integration of renewable energy, the grid-connected operation of AC/DC systems, and the widespread use of non-linear and impact loads (e.g., high-voltage, high-capacity power electronic equipment), the issue of dynamic reactive power in power grids has become increasingly prominent. Dynamic reactive power compensation devices(SVG), owing to advantages such as fast dynamic response and strong capability to suppress voltage flicker, have gained extensive application.

However, effective testing methods or systems for SVG devices manufactured by various vendors have long been lacking. To address this, Shanghai KeLiang has summarized years of engineering experience in power electronics and power system testing. Referencing relevant industry standards, the company developed an SVG Grid-Connection Detection System, which effectively shortens the development cycle of SVG controllers and provides reliable, standardized grid-connection testing.

Traditional testing methods struggle to evaluate the full functionality and performance of SVG controllers. Many grid-supporting functions remain unverified, especially those claimed by manufacturers in their corporate standards—performance metrics that cannot be accurately quantified before deployment. Consequently, KeLiang proposed an HIL -based SVG Grid-Connection Detection System to study SVG’s effectiveness in resolving practical grid issues.

The Keliang SVG Grid-Connection Detection System consists of three subsystems: Test Management Subsystem, Real-Time Simulation Subsystem and Signal Interface Subsystem.

The Test Management Subsystem serves as the host computer for testing, featuring capabilities such as model development, test management, automatic testing, and graphical monitoring.

The real-time simulation subsystem comprises one OP5600 real-time simulator and one OP5607 FPGA simulator. This system supports functionalities including real-time execution of mathematical models and real-time I/O port configuration. Specifically, the main circuit model of the three-phase AC system runs on the OP5600's CPU, while the SVG model composed of cascaded H-bridges operates either on the OP5600's CPU (with a step size <25μs) or on the OP5607's FPGA (with a step size <1μs). Data communication between the OP5600 and OP5607 occurs via the PCIe bus.

The Signal Interface Subsystem provides physical connections to physical devices such as the SVG control cabinet, Intelligent Fiber Interface Box, and power amplifiers. On one hand, analog values from I/O outputs are fed into the controller for control algorithms. On the other hand, the Valve-Based Controller (VBC) within the control system communicates with the simulator and Intelligent Fiber Interface Box via high-speed fiber optics. The controller issues signals including IGBT switching commands for each H-bridge submodule,while simultaneously receiving signals such as capacitor voltage levels and fault flags from each submodule.

During the overall planning phase of the SVG and AC system, as well as the engineering parameter design phase of the SVG, detailed SVG models can be utilized for research and analysis in the development and design stages to refine the SVG's engineering parameters.

• During the design and development phase of SVG control logic and control algorithms, detailed SVG models enable comprehensive testing of various control performances, thereby optimizing the control logic and algorithms.

• Upon completion of the SVG control and protection design, the system can perform complete grid integration performance testing on the SVG controller—either manually or automatically—in compliance with the State Grid Corporation of China enterprise standard Q/GDW241-2008 Chain-type Static Synchronous Compensator.

The KeLiang SVG Grid-Connected Testing System offers the following advantages:

• Custom Engineering Models

The system features various detailed power system models based on CPU or FPGA platforms, calibrated through real-world engineering applications. These include:FACTS models (e.g., SVG, UPFC),MMC-HVDC models (Modular Multilevel Converter High-Voltage Direct Current),Traditional grid models and renewable energy system models (e.g., wind/solar integration), also customizable testing models tailored to user requirements.

• Human-Machine Interface (HMI)

Leveraging LabVIEW-based graphical interface development, the HMI adheres to power system specifications and operational conventions. This design ensures flexible, intuitive, and efficient operations, enhancing user control and system interactivity.

• Automated Testing Workflow

Based on relevant industry standards for SVG grid-connection testing and integrated with our company's self-developed QuiKLab automated testing software, we have custom-developed a professional automated grid-connection testing process for SVG that enables fully automated operation from simulation analysis to test report generation.

SVG Grid Integration Testing at an Electric Power Research Institute

Solution: As shown in the figure below, the entire system can be divided into four parts: the Host System, Real-Time Simulator, Signal Interface System, and SVG Controller. The Host System provides functions such as model development, real-time simulation management, automatic testing, and graphical monitoring. The Real-Time Simulator serves as the lower-level system and acts as the core subsystem of the entire system. The Signal Interface System mainly consists of fiber optic interface boxes and power amplifiers, enabling physical connectivity and signal interaction between the simulation system and controllers. The SVG Controller, used to control the SVG model, typically operates in two control modes—constant voltage mode and constant reactive power mode—and functions as the Device Under Test (DUT) in the complete SVG testing process.

For this project, an SVG composed of 11 cascaded H-bridge submodules per phase is utilized. The CPU model provided by KeLiang demonstrates simulation results that align with actual operating conditions. Its dynamic responses accurately simulate the characteristics of both the power grid and the SVG, offering a solution for SVG grid compliance testing.

Project Outcomes: After the complete setup of the project environment, both functional testing and dynamic performance testing met the requirements specified in the test protocol. KeLiang successfully executed the entire SVG grid compliance testing, validating the control function and control performance of the SVG controller. This achievement reduced testing costs for the electric power research institute, enhanced testing efficiency, and ensured that the safety, reliability, and stability of the SVG grid integration fully complied with relevant technical standards.

KeLiang has successfully developed an automated grid compliance testing process for SVG (Static Var Generator) in accordance with industry standards, utilizing its self-developed QuiKLab automated testing software. This solution enables fully automated operation from simulation analysis to test report generation. Additionally, a human-machine interface (HMI) compliant with power system specifications and user habits was developed using LabVIEW, offering user-friendly operation as a comprehensive SVG grid integration testing solution.

KeLiang has participated in multiple domestic SVG testing projects and has accumulated extensive experience in embedded system testing engineering services across power, aviation and automotive sectors. In the future, as more renewable energy sources are integrated into the grid, grid access testing will become an inevitable trend and a critical step. SVG shares significant similarities in control methodologies with many grid-connected inverters.