This paper demonstrates the potential of inverter-based loads to support grid reliability during power system transients thereby enabling reliable integration of renewable energy in power systems. Such loads are referred to in this paper as grid-supportive loads (GSLs). A new GSL model is developed that simulates the transient response capabilities that can be programmed in electronic loads. The model’s design enables it to be easily integrated in widely used commercial power system transient analysis software. Theoretical expressions are derived that explain the workings of the GSL model. The performance, numerical stability, and impact of the GSL model is validated on 9-bus and 2000-bus synthetic power system models using generator tripping and bus fault disturbances. Results on the 2000 bus system show that in the absence of frequency support from wind/solar generation resources, just 20% of loads with grid-supportive capabilities can improve frequency response by up to 2000 MW/0.1 Hz and reduce deviation in frequency at nadir by up to 60% compared to the situation when GSLs are absent. Power system reliability also improves under fault events. It is further shown that GSLs can aid in integrating more renewable generation without degrading the overall transient response of the power system.

Integrated transmission and distribution (T&D) analysis is a new research area in power systems that has gained traction in recent years to study the impacts of rapidly growing penetration levels of distributed generation, particularly solar photovoltaics (PV), on power systems. This paper demonstrates the advantages of studying the impact of PV on power system dynamics using three phase, integrated T&D models instead of the positive-sequence transmission-only models. The three phase integrated T&D models include detailed models of substations that connect the transmission and distribution systems. It is demonstrated that by more accurately simulating disturbances as they would occur in the field, and by preserving the geographic diversity of PV generators, dynamic simulation of integrated T&D models avoids overestimation or underestimation of the impact of PV on power systems.

The increasing integration of inverter-based renewable generation presents challenges for the frequency stability of power systems, primarily due to reduced system inertia and governor response—collectively known as Fast Frequency Response (FFR). Obtaining FFR from inverter-based generation requires reserving operational headroom, resulting in a lost opportunity to generate more renewable energy. Recently, inverter-based loads have been proposed as potential sources of FFR; however, critical gaps remain in the control algorithms needed to transform these loads into grid-supportive loads (GSLs) capable of delivering FFR. To address this gap, this paper introduces a novel algorithm that enables automatic, communication-free, grid-supportive behavior in inverter-based motor loads. The algorithm’s efficacy is demonstrated through comprehensive simulations and hardware experiments. Experimental results demonstrate that GSLs equipped with the proposed controller can provide FFR by adjusting power consumption, reducing it by up to 32% for a 1.8% drop in grid frequency and increasing it by 10.65% for a 0.4% rise, within 1.5 seconds in response to frequency events. By retrofitting existing, or designing new inverter-based motor loads with this controller, end-use devices can automatically deliver aggregated FFR without communication infrastructure, enhancing frequency stability in grids with high levels of variable renewable energy.

It has been suggested in the literature that by reducing the incoming voltage at a distribution feeder head or at the supply side of buildings, significant electricity savings can be achieved. This technique is called Conservation Voltage Reduction (CVR). Data-based analysis with and without CVR is primarily used to support such assertions, which does not explain the physics behind reduction in energy consumption with CVR. This paper presents a new approach for evaluating the impact of CVR on cooling equipment. In this approach, a thermal-electric model of the cooling process is developed in MATLAB’s SIMSCAPE toolbox that can be used to explain the physics behind energy reduction with CVR. This model includes an accurate model of a compressor coupled to an induction motor whose supply voltage can be varied to simulate CVR. Simulations performed using this model show that the Coefficient of Performance (COP) of cooling equipment improves with a reduction in supply voltage. However, the energy lost in the motor windings may nullify the impact of the improvement in the COP and render the CVR programs ineffective if the range of speed change is small over the allowable voltage change. The simulation results show an increase in energy consumption of 4% at 90% rated voltage compared to the energy consumed at the rated voltage. However, if variable frequency drives-based cooling equipment is appropriately controlled, it is possible to reduce their net energy consumption using CVR. Simulations performed keeping the ratio of the supply voltage and the frequency constant showed a reduction in energy consumption of 2.5% at 90% rated voltage compared to the energy consumed at the rated voltage. Thermal-electric modeling of building cooling equipment is, therefore, vital to accurately evaluating the benefits of CVR as smart, power electronics-based end-use equipment is globally adopted.