Assessment of Conservation Voltage Reduction Capabilities Using Load Modelling in Renewable-Rich Power Systems

Abstract : The conservation voltage reduction (CVR) and load modelling have acquired a renewed interest in reassessing the CVR capabilities and load model parameters for renewablerich distribution networks. The underlying theoretical views behind the changes in load model parameters and subsequent CVR capabilities in the distribution networks caused by the high penetration of renewable generation have yet to be explored. This research has presented a mathematical analysis of equivalent network impedance with integrated distributed generations (DG) and further established a relationship of the equivalent network impedance with the static load model parameters and CVR to accurately assess the impact of DGs on the CVR. Then, this paper has demonstrated various case studies with IEEE 33 bus network to analyze and validate the changes in static load model parameters due to the integration of renewable DGs and batteries into the balanced and unbalanced power systems. The obtained results verify the increased CVR capabilities of a distribution network, caused by the higher active power exponent in the load model parameters, as affected by the integration of renewable DGs.
 ? In this work combined effect of CVR with distributed generation on distribution network for the analysis, energy efficiency has been proposed. ? Few research works have been reported for the analysis of the impact of DG during CVR operation. ? A high-level analysis of potential locations was completed, taking into account the existing Microgeneration regulation in Alberta, where customers connecting an amount of renewable generation not exceeding 5 MW in nameplate and not having energy production exceeding annual energy consumption, would qualify for special treatment; hence, they have a higher likelihood to propose such interconnection.
 ? It has the potential to substantially increase the hosting capacity, but interestingly high DER penetration does not negate the effectiveness of the CVR scheme. ? In other words, CVR enables higher DER nameplate installation with very little impact on energy savings, making CVR a suitable grid modernization strategy for DER-rich systems. ? This is especially true in systems such as the one used in this paper, that of a northern electric utility that experiences very long sunny days during the summer. ? The paper is structured as follows. provides a brief background on the problem of voltage rise due to DERs and their smart inverter performance.
 • In this paper, a conservation voltage reduction (CVR) scheme is proposed for a distribution system with intermittent distributed generators (DGs), such as photovoltaics and wind turbines. • Furthermore, studies such as have proposed energy management systems in microgrids that can not only manage the large penetration of renewable energy sources, but can also optimize the energy consumed. • The proposed method is validated using a modified IEEE 123-node test feeder. • With the proposed method, the voltages of the test system are maintained to be greater than the lower bound, even though the active power outputs of the DGs are varied.
 ? Power system behaviors, including steady-state and dynamic performances, are greatly dependent on the effective load characteristics. ? A voltage-dependent load model is intuitively a static exponential load model that shows the relationship of power with voltage as an exponential equation. ? The mathematical formulation of the network equivalent impedance (Zeq), load model parameter (Kp), and CVR shows that the higher Kp value (denoting a small change in the voltage can lead to a higher power variation) essentially can enhance voltage-controlled demand management capability. ? This assessment can be used to ensure better performance of voltage-controlled demand management in the renewable-rich distribution networks.

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