Inertia Response Improvement in AC Microgrids: A Fuzzy-Based Virtual Synchronous Generator Control

Abstract

The absence of rotational masses from synchronous generators in converter-interfaced microgrids leads to a lack of inertia. Consequently, the system exhibits steeper frequency variations and higher frequency nadir, which may degrade the dynamic performance and challenge the operation of sensitive equipment such as protective relays in the grid. Virtual synchronous generator is introduced as an effective solution to increase the inertial response of converter interfaced renewable energy sources. This paper proposed a fuzzy controller, which is augmented on the virtual synchronous generator topology to damp the perturbation during transients by increasing the inertia of the system. The proposed fuzzy control adds a correction term to the the governor's output power that increases the system inertia during transients. In order to compare the inertial response improvement, a comparison between proposed fuzzy control technique and cost function based inertia and damping coefficient optimization is done on a virtual synchronous generator platform. It is shown that online measurement based adaptive methods have a better inertial response against other time-consuming techniques. To further verification, a number of experiments are done, which confirm the merits of the proposed fuzzy based virtual synchronous generator control method.

Small‐signal analysis of multiple virtual synchronous machines to enhance frequency stability of grid‐connected high renewables

“…RES/load power changes), each VISMA unit increases or decreases its emulated power until reaching a new common operating frequency. As shown in (15) and Figure 4, the amount of emulated power from each VISMA to compensate the disturbance depends on the VISMA's droop characteristic. Then, the dynamic relationship in (14) can be modified to include the dynamic effect of the P-f droop control as…”

“…The authors in [14] presented a method to select proper VISMA parameters regarding system frequency protection scheme. Then, the authors applied the robust control theory [17], model predictive control [12] and fuzzy logic [15,16] to determine optimal VISMA parameters regarding system stability enhancement. Consequently, it becomes a promising technique for integrating RESs into the existing power systems.…”

Adaptive inertia emulation control for high‐speed flywheel energy storage systems

“…Conventional synchronous reference frame phase‐locked loop (SRF‐PLL) has been used extensively for inertia emulation in numerous works [30, 33, 34, 41, 43]. However, other works show that the use of the SRF‐PLL for inertia emulation can lead to instabilities, unrealistic values, and noise amplification associated with the derivative operation [31, 44, 45].…”

Microgrid Frequency Fluctuation Attenuation Using Improved Fuzzy Adaptive Damping-Based VSG Considering Dynamics and Allowable Deviation

“…Hence, the robustness of the methods is low. On this ground [28][29][30][31] adopt the fuzzy controllers to tune the inertia of the VSG, which comply with the nonlinear properties of the system and are relatively simple and robust, but there still exist several problems. Firstly, the damping that is also closely related to the frequency response (as in [24]) is seldom separately employed for frequency fluctuation attenuation in these researches, which means that the fuzzy adaptive damping VSG control technology needs further investigation.…”