Application Background

For large-scale grid connections, wind turbine generator systems (WTGSs) face immensely complex working conditions. To ensure the normal grid-connected operation of renewable energy generating systems, in the industry's product iteration process, during the actual "R&D—production—testing" steps, R&D and test engineers must make repeated attempts to change control parameters, filter parameters and perform a series of WTGS tests under varying conditions. Based on the characteristics of hardware-in-the-loop simulation, which supports the construction of arbitrary topology models and is highly accurate, the use of hardware-in-the-loop for wind turbine grid-connection testing has become the mainstream trend.

By utilizing ModelingTech's self-developed MT6040 HIL real-time simulator, enterprise engineers are helped to conduct HIL simulation research and testing on WTGSs as outlined below:

1) Application research on the topological structure of new wind power converters 

2) WTGS HV/LV ride-through testing and impedance analysis testing

3) Research on power control of micro-grid system including wind power system and energy storage system and its influence on power grid

4) Control performance verification on new control boards/control algorithms 

Solution

Carry out the simulated operation of a real physical unit, connecting to the physical interface with a real controller, by means of ModelingTech's MT6040 simulator, helping enterprises conduct testing on their independently developed control boards for the purpose of ex-factory testing and control effect verification.

Test Contents

Use of ModelingTech's MT6040 real-time simulation platform can facilitate access to all equipment admittance testing (power electronics), such as HV/LV ride-through testing, broadband oscillation impedance characteristic testing, external reactive small disturbance testing, power grid adaptability testing, etc.; it can also effectively prevent controller-induced "meltdowns", thus providing enterprises with a safe and cost-effective test platform.

1. HV/LV ride-through testing

According to the "Testing Regulations for Fault Voltage Ride Through Capability of Wind Turbines" (GB/T 36995-2018) and "Technical Regulations for Wind Farm Access to Power System" (GB/T 19963-2021) test standards, the WTGS' responsiveness to transient voltage dips/rises is tested to ensure the WTGS can maintain steady and safe operation despite grid voltage fluctuation. 

2. Broadband oscillation impedance characteristic testing

According to the requirements of "Technical Specifications for the Evaluation of Wind Farm Impedance Characteristics" (NB/T 10651-2021), Using the voltage disturbance injection method to scan the impedance, the operating conditions with active power output of 10%, 30%, 40%, 60%, 80%, and 90% can be considered to scan the impedance of the wind turbine, and provide the positive sequence impedance and negative sequence impedance of the wind turbine in the range of 2.5Hz-1000Hz. If there is a risk of oscillation, the control parameters should be optimized or the control strategy should be improved to achieve impedance reshaping to suppress the oscillation.

3. External reactive small disturbance testing

Set the busbar switching capacitor of the wind turbine to simulate different reactive power injection into the wind turbine to test whether the wind turbine can run stably.

4. Grid adaptability testing

According to the requirements of "Test Regulations for Grid Adaptability of Wind Turbines" (GB/T 36994-2018), the grid adaptability of wind turbines is tested to ensure normal operation of wind turbines. The test contents mainly include: voltage deviation adaptability, frequency deviation Adaptability, three-phase voltage unbalance adaptability, flicker adaptability, harmonic voltage adaptability.

Platform Advantages

● High Accuracy

The LC + RonRoff hybrid modeling approach, the first of its kind in China, is adapted for various application scenarios, from low frequency to high frequency conditions. LC modeling is suitable for use at low switching frequencies and RonRoff modeling is utilized at high switching frequencies, without excess switching loss, making the simulation results closer to the real physical system. 

● High Stability

Using the RonRoff modeling method to model the circuit breaker, users can perform HV/LV ride-through testing through “case switching”, avoiding the risk of oscillation of the circuit breaker under traditional LC modeling, and making the HV/LV ride-through testing results consistent with the actual physical System test results remain consistent.

● High Reliability

Supports an industrial user broad voltage range DI and CAN/RS485/RS-232 communication protocols, and following numerous closed-loop tests, it has become the first choice for many well-known domestic wind power inverter manufacturers for use in R&D and testing!

● Excellent Accessibility

It is characterized by compatibility with mainstream modeling simulation software, no need for FPGA programming compilation and abundant IO interfaces, which can greatly improve the real-time operation efficiency when users constantly change the model and modify parameters in the simulation test. Simple aerial plug-in and survey interface is convenient for users to expand and analyze.