Abstract
Insufficient inertia is the paramount challenge in power system transition toward <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 100\%$</tex-math></inline-formula> converter-based generation. A promising solution to this issue is utilizing distributed virtual inertia (DVI) concept, i.e., releasing energy stored in the dc-link capacitors of power converters employed in the grid following a frequency disturbance. Nevertheless, this method has two drawbacks: <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 1$</tex-math></inline-formula> ) the dc-link voltage is not reverted to its reference value after the power mismatch between generation and demand, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 2$</tex-math></inline-formula> ) it yields instability of a local mode associated with the control system when the converter operates in weak grids. To overcome the aforesaid problems, the conventional DVI loop is modified so as not to affect the outer loop voltage regulator after transient. Moreover, an efficient compensator is presented in this article which eliminates the adverse impact of DVI technique on the converter stability in weak grid connections. The efficacy of proposed control scheme is depicted by simulations in MATLAB. The results illustrate that an improvement of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$ 23\%$</tex-math></inline-formula> is evident in the grid frequency rate of change following a frequency contingency collated with the case in which the DVI loop staying nullified.
Highlights
T HE current energy arena is changing, from fossil fuel−based generation to power electronic converter interfaced renewable generation
The preceding small−signal analyses affirmed that the distributed virtual inertia (DVI) loop induces instability to the converter operating in weak grids
An enhanced DVI−based control strategy for grid−tied power converters employed in weak power systems has been proposed
Summary
T HE current energy arena is changing, from fossil fuel−based generation to power electronic converter interfaced renewable generation. The inherent inertia of synchronous machine acts as the first response to frequency events (e.g. any mismatch in the supply−demand balance) by providing or absorbing kinetic energy to or from the grid. Diminution of system inertia limits further increases in RESs penetration [8] This is because RESs integrating into the network through power converters do not inherently contribute to the system inertia. To address this issue, synthetic inertia concept (defined as the contribution of a converter−based generator to emulate the inertial response of real SGs [9], [10]) has been proposed through a plethora of mechanisms; i.e. readjusting converter power reference in response to disturbances, which is analogous to the kinetic energy released or absorbed by the SGs
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