Tweet

Posted on 02 September 2019

Test and Validation of Grid Connected Battery Storage Controller

Free Bodo's Power Magazines!

 

 

 

Desktop power electronics control testing

Transmission and distribution (T&D) grid connected energy storage controlled by power electronics (PE) improves power quality, and reduces the need for additional investments in T&D infrastructure, but assumes well tested control algorithms that comply with T&D grid codes.

To streamline the process of grid connected converter controller development a HIL600 device is ideal because it enables rapid and exhaustive test and validation of PE controller implementation. In this article HIL600 is used to verify the performance of a novel power flow control strategy under unbalanced grid voltage conditions.

By Luc Meysenc, Schneider Electric,
Zoran Ivanovic and Nikola Celanovic, Typhoon HIL, Inc.

Grid connected energy storage technology

Speedy integration of the energy storage technology into the electricity transmission infrastructure is one of the important prerequisites for the continued growth of energy produced by renewable energy sources.

There is a variety of technologies that can be used to store energy, which all need a fully controllable power electronics grid interface, most often in the form of a 4Q voltage source converter (VSC).

The control of a grid connected VSC is challenging in large part because of the compliance with the numerous grid codes, which vary between the countries and are becoming more stringent and thorough. For example, IEEE has an area of more than 100 active standards, or standards in development with relevance to future smart grids, and among those are several that directly pertain to energy storage systems. IEEE P2030.2 is guide for interoperability of energy storage systems integrated with electrical power infrastructure, while IEEE P2030.3 is standard for test procedure of electrical energy storage equipment. IEEE1547 represents series of interconnection standards, providing also rules for inclusion of energy storage into electrical power systems.

One important topic, which is the focus of this article is the optimization of the grid connected VSC control strategy for operation with unbalanced grid. Thanks to the proposed algorithm a proposed "smart" energy storage device can, by injecting correct amount of active and reactive power, support the unbalanced T&D grid.

Testing and validation of control systems using a HIL platform

Traditionally, the controller testing has to be in large part carried out on a real PE systems, left half of the Figure 1, which makes it costly and time consuming. Particularly the repetitive tests due to subsequent software releases and certification for various countries becomes time consuming.

HIL enables testing of controller implementation in the safety and comfort of the office

By modelling the power part in an easy to use HIL with 1μs time resolution, shown in the right half of the Figure 1, it is now possible to repetitively and inexpensively test operating points that were impractical or impossible to do in the laboratory. Test and Validation of a novel grid connected battery storage controller In this example, we investigate the performance of the novel dual vector current controller (DVCC). Because the DVCC regulator regulates both positive and negative sequence current components independently it shows a much improved performance during grid unbalance compared to classical DQ vector controller. Figure 2 shows the controller block diagram where the three-phase grid voltages and currents are measured and transformed into positive and negative sequence in synchronously rotating reference frame. The DVCC current controller comprises two pairs of PI regulators one for positive the other for negative sequence components. Details about controllers and extraction of sequence components could be found in [1].

DVCC grid connected control structure

Real-time implementation

The system hardware is simulated in real time on the HIL600 platform with a time-step of 1μs, while the control system PWM carrier frequency is 2 kHz. The model of proposed hardware is shown in Figure 3. It consists of energy storage in the form of multi cell batteries, VSC inverter, transformer and electrical grid. Transformer is needed for connection to the medium voltage grid (6 kV). The rated power of the whole system is 1.8 MW.

Schematic diagram of batteries based energy storage system

The controller is implemented on the Texas Instruments control card with TMS320F2812 DSP. The HIL600 tool chain was used to emulate the power circuit from Figure 3.

HIL test results

Figure 5 and 6 show the phase currents of the DVCC controlled grid connected converter during the two phase 50% voltage sag from Figure 4.

Three-phase voltages during voltage sag

Active and reactive power of the DVCC controlled converter during 2-phase voltage unbalance

Grid currents of the DVCC controlled converter during voltage sag

During the voltage sag the proposed DVCC controller suppresses oscillations in active power, maintains the average reactive power at zero, and limits the amplitude of the grid current. The active power is set to 80% of the nominal during the sag.

Summary

The HIL600 system was proven to have the fidelity to model the real converter connected to the T&D grid and even more importantly an unmatched ease of use and flexibility to choose the circuit topology and circuit parameters, and specify the disturbances that are often difficult if not outright impractical to do in the laboratory.

References
Z. Ivanovic, E. Adzic, M. Vekic, S. Grabic, N. Celanovic, V. Katic, “HIL evaluation of power flow control strategies for energy storage connected to the smart grid under unbalanced conditions” IEEE Trans. Power Electron., vol. 27, no. 11, pp. 4699-4710, Nov. 2012.

 

VN:F [1.9.17_1161]
Rating: 0.0/6 (0 votes cast)

This post was written by:

- who has written 791 posts on PowerGuru - Power Electronics Information Portal.


Contact the author

Leave a Response

You must be logged in to post a comment.