STABILITY MECHANISMS AND ACTIVE SUPPORT CONTROL IN CONVERTER-DOMINATED POWER SYSTEMS WITH HIGH RENEWABLE PENETRATION
Keywords:
Converter-dominated power systems, grid-forming converters, virtual inertia, battery energy storage, transient stability, frequency support, v, Python simulationAbstract
Power Systems with High Penetration of Renewables Trends of inverter-based renewable generations replacing synchronous machines and reducing the rotational inertia that has historically maintained AC power grid security is ongoing. In a conveter-dominant power system, frequency excursions in the transient, rate-of-change-of-frequency sensing leading to relayblind clearance operations, and inability for voltage to support recovery, are the security-limiting factors. This paper presents a dynamic modelling method and transient stability calculation scheme for low-inertia power system that has been implemented in a Python-based power system dynamic simulator, including turbogenerator synchronising machine models, grid-following (GFL) converter machine models based on explicit phase-locked-loop (PLL) states, grid-forming (GFM) converter models with a matching-control swing equation, battery energy storage systems (BESS) providing fast frequency regulation. The paper describes a coordinated control scheme grid-forming power-frequency loop retuning between converters and BESS for time-domain simulation, BESS implementation for sub-second frequency regulation, and reactive power arbitrator between converters and BESS. The framework is applied to a modified IEEE 39-bus test system at renewable penetration levels ( with respect to the system load of 30%, 50%, 70%, and 90%. Relative to the uncoordinated comparison, the method minimizes the penetration) and increases the nadir of the frequency by as much as 0.27 Hz (above the under-frequency load-shedding limit). Small-signal eigenvalue analysis confirms damping is kept above 5% for PLL bandwidths as high as 350 rad/s. The model is validated to an IEEE 39-bus unmodified PSS/E benchmark for the PSS/E absolute metric error of−0.032 Hz/s for RoCoF and−0.009 Hz for the frequency nadir. From the results are quantitative penetration boundaries and design ideas for stable operation of future converter-dominated converters, virtual inertia, battery energy storage, transient stability, frequency support, low-inertia systems, Python simulation.
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