Inertia Emulation Through Supercapacitor for a Weak Grid

Abstract

Renewable energy sources (RES) have been widely incorporated into the power generation to offset fossil fuels in order to minimize carbon emissions. Typically, RES based power generation integrated into the power grid through the power electronic converters. These power electronic converters decouple the source from the load without providing inertia. As a result, inertia of the power grid decreases, resulting in undesirable load shedding and cascading failures under power imbalances. In order to preserve stability during contingency events, it is important to add inertia support to the grid. This paper demonstrates inertia emulation from the supercapacitor (SC) to resolve the low-inertia issue. Inertia emulator based on supercapacitor (IESC) is formulated to generate inertial power by proportionally linking the grid frequency to the active power reference of SC. This paper proposes an enhanced emulated inertia control (EIC) technique based on the frequency deviation and frequency derivative to address low inertia. EIC technique controls the inverter associated with IESC to exhibit the equivalent inertia characteristics as the synchronous generator. Further, the selection of the capacitance value of SC is derived to achieve the required inertia constant. The small-signal stability of IESC is demonstrated using the power angle curve. Further, the stability of the EIC is verified through bode plot. Simulation and hardware-in-loop (HIL) results are provided to verify the effectiveness of EIC employed IESC in a weak grid.

Exploring the Utilization of Energy Storage Systems for Frequency Response Adequacy of a Low Inertia Power Grid

“…is the required rated size of BESS (in MW) to keep system frequency above a certain value. Using this modified expression of ∆ in (4), swing equation can be rewritten as (14).…”

“…Among them, Li-ion batteries are widely used as storage medium. Alternative lithium batteries [12], Ni-Cd, lead-acid, vanadium redox flow batteries, flywheels [13], supercapacitors [14] and Superconducting Magnetic Energy Storage (SMES) [15] are also employed for frequency support. Their response time, installation cost, operational cost, sustainability and life spans are described in [16].…”

“…However, none of these illustrated works emphasis on finding appropriate sizing of the aforementioned energy storages and their economic feasibility. For instance, in [14], the authors only demonstrate the competency of ultracapacitor installation under different load condition. Furthermore, effectiveness of supercapacitor installation is not compared with any existing technologies such as synchronous condenser, BESS, SMES and so on.…”

An Enhanced Emulated Inertia Control for Grid-Connected PV Systems with HESS in a Weak Grid

“…Furthermore, the performance of super-capacitor (SC) in the inertial response is satisfactory. In [22][23][24] the SC's usage in the inertial response is proposed, although, the aggregate of battery and SC is taken into consideration because of its advantages: decreases the battery size, increases the battery's lifespan, provides the inertial response, and higher system efficiency [25]. In hybrid energy storage systems (HESS), the SC is utilized to supply a highly variable power component, and the battery is used to handle the slowly variable power component.…”

Inertia Theory Frequency Dynamic Analysis and Control of Power System with High Proportion of Renewable Source

“…However, previous EIC research has primarily focused on controller design, with only a few researchers discussing EIC functional implementation [29]. e concept of deloading control method for PV systems in addition to the EIC for controlling frequency and providing an inertial response is also proposed [30]. On the other hand, PV modules are forced to operate at a lower power level.…”