Impact of Reverse Power Flow on Distributed Transformers in a Solar-Photovoltaic-Integrated Low-Voltage Network

Majeed, Issah Babatunde; Nwulu, Nnamdi

doi:10.3390/en15239238

Cited by 14 publications

(8 citation statements)

References 50 publications

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“…(a) Measure HTs secondary AC currents, i a2 , i b2 , and i c2 . Subsequently, process their normalized values through a Park transformation to extract their d, q components, as depicted in (14).…”

Section: Performance Evaluation Via Case Studiesmentioning

confidence: 99%

“…With the proliferation of renewable energy systems like wind turbines and solar PV systems, their accelerating grid penetrations not only result in the deterioration of supply voltage quality but also lead to reverse power flow in the distribution substations. The unrestricted reverse power flow can further lead to operational security issues like significantly increased transformer losses (and hence reduced lifetime) and the malfunction of protection relays [14,15]. Currently, there are no standard solutions for restricting the reverse power flow.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Mode Control of a Hybrid Transformer for the Coordinated Regulation of Voltage and Reverse Power in Active Distribution Network

Xu,

Zhang,

Qiu

et al. 2024

Processes

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The unprecedented growth of distributed renewable generation is changing the distribution network from passive to active, resulting in issues like reverse power flow, voltage violations, malfunction of protection relays, etc. To ensure the reliable and flawless operation of active distribution networks, an electrical device enabling active network management is necessary, and a hybrid distribution transformer offers a promising solution. This study introduces a novel hybrid transformer topology and multi-mode control strategy to achieve coordinated voltage and reverse power regulation in active distribution networks. The proposed hybrid transformer combines conventional transformer windings with a partially rated SiC-MOSFET-based back-to-back converter, reducing additional investment costs and enhancing system reliability. A multi-mode control strategy is proposed to facilitate the concurrent reverse power control and voltage violation mitigation of the presented hybrid transformer, allowing a smooth transition between the P–Q control mode and the V–f control mode. The control mode switching can be activated manually or autonomously in response to voltage violations or reverse power overloading. The effectiveness of the proposed hybrid transformer configuration and its control mode transition mechanism are examined through comprehensive case studies conducted in the PSCAD/EMTDC environment. The proposed HT design has been confirmed to achieve a voltage regulation range of ±20% of the nominal voltage and effectively regulate bidirectional active power flow within a range of −25% to 25% of the rated power.

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Section: Performance Evaluation Via Case Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-Mode Control of a Hybrid Transformer for the Coordinated Regulation of Voltage and Reverse Power in Active Distribution Network

Xu,

Zhang,

Qiu

et al. 2024

Processes

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show abstract

“…The total active power produced by RDGs should be no larger than the system's total active power demand because the violation of this constraint results in a reverse power flow in the system [33]. This constraint is expressed as follows.…”

Section: Feasibility Constraintmentioning

confidence: 99%

Optimal Location and Sizing of Renewable Distributed Generators for Improving Robust Voltage Stability Against Uncontrollable Reactive Compensation

et al. 2023

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The penetration level of renewable energy sources is increasing worldwide with incentives and subsidies for declining greenhouse gas emissions. Nevertheless, determining the optimal location and size of renewable distributed generators (RDGs) remains a challenging task, owing to the uncontrollable reactance that dominates power distribution networks in voltage control and its sensitivity to weather conditions. Hence, without considering the reactive compensation of generators, RDG integration incurs undesired total power losses and puts the system at risk for voltage instability and collapse. This research proposes Load Disabling Nodal Analysis for Robust Voltage Stability (LDNA-RVS), a method that determines the optimal location and size of RDGs and aims to improve robust voltage stability by considering reactive compensation while enhancing the loss reduction efficiency (LRE) of the RDG integration. The proposed LDNA-RVS method has been successfully applied to the IEEE 33-bus and IEEE 69-bus test distribution systems, demonstrating its suitability for small-scale systems with a limited number of RDGs. Finally, LDNA-RVS outperforms other methods in six out of eight categories for robust voltage stability and achieves the top rank in all eight categories for LRE. These findings prove the effectiveness of LDNA-RVS in terms of robust voltage stability and LRE against the uncontrollable reactive compensation.

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“…2 of 25 identified through the electric distribution substation (EDS), ensures the connection between the MV and LVEDNs and represent the reason for various voltage issues, leading to uncertainties on the voltage level of the nodes [5,6].…”

Section: Motivationmentioning

confidence: 99%

Expert System Integrating Rule-Based Reasoning to Voltage Control in PV-Rich Low Voltage Electric Distribution Networks

Dandea¹,

Grigoraș²

2023

Preprint

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Nowadays, in low voltage (LV) electric distribution networks (EDNs), the Distribution Network Operators (DNOs) are encountering a high number of connected small-scale distributed generation units, mainly photovoltaic (PV) prosumers. The irregular behavior of the prosumers, together with the uncertainty degree of the requested and injected powers associated with all end-users from the LV EDN, can cause voltage variations with violations of the allowable limits. In this context, the paper developed an efficient and resilient expert system integrating the rule-based reasoning applied to the On-load Tap Changer (OLTC)-fitted transformer to improve the efficiency of the voltage control in the PV-rich LV EDNs. An in-depth analysis based on 75 scenarios, resulting from the combinations of three indicators: the penetration degree of the PV prosumers, consumption evolution associated with the consumers, and energy production of the PV systems, has been performed to demonstrate the efficiency of the proposed expert system in an LV EDN from a rural area belonging to a Romanian DNO. The success rate of the expert system has been 86.7% (65 out of 75 scenarios didn't have voltage issues, all values being between the allowable limits in 100% of the time slots associated with the analyzed period). For the other scenarios (representing 13.3%), the values have been inside the range [-10%, +10%] at least 95% of the time slots, according to the European Power Quality Standard, and for the rest of the time slots up to 100% being very close to the upper and lower limits of the range, with highly mitigating of the voltage variations.

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Impact of Reverse Power Flow on Distributed Transformers in a Solar-Photovoltaic-Integrated Low-Voltage Network

Cited by 14 publications

References 50 publications

Multi-Mode Control of a Hybrid Transformer for the Coordinated Regulation of Voltage and Reverse Power in Active Distribution Network

Multi-Mode Control of a Hybrid Transformer for the Coordinated Regulation of Voltage and Reverse Power in Active Distribution Network

Optimal Location and Sizing of Renewable Distributed Generators for Improving Robust Voltage Stability Against Uncontrollable Reactive Compensation

Expert System Integrating Rule-Based Reasoning to Voltage Control in PV-Rich Low Voltage Electric Distribution Networks

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