Optimal Tap Setting of Voltage Regulation Transformers in Unbalanced Distribution Systems

Robbins, Brett; Zhu, Hao; Domínguez-García, Alejandro D.

doi:10.1109/tpwrs.2015.2392693

Cited by 120 publications

(80 citation statements)

References 17 publications

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“…The uncertainties escalates the issue. Some previous works applied simplified formulations, e.g., linearized formulations [12], and also simplified models for DCDs, e.g., round-off approaches [13]. There is no guarantee that the solution is optimal or even feasible with these methods.…”

Section: A Literature Reviewmentioning

confidence: 99%

“…semidefinite programming was used in [18] to solve the DSP in an unbalanced system without considering the mutual inductance between the phases. Neglecting the voltage unbalance at system buses, semidefinite programming was applied in [13] and [19] to solve the DSP. These assumptions are not reasonable for practical systems, where voltage unbalance really matters and sometimes voltage unbalance minimization is at least considered as one of the objectives.…”

Section: A Literature Reviewmentioning

confidence: 99%

“…A perturbed relationship between I, V and tap is given in (13). Matrices A and B are defined in (13) and (14), respectively.…”

Section: A Fast Control Devicesmentioning

confidence: 99%

“…A perturbed relationship between I, V and tap is given in (13). Matrices A and B are defined in (13) and (14), respectively. The relationship between the voltage and current at the secondary bus and the OLTC control variables (tap) is shown in (12), where C and D can be found using Fig.…”

Section: A Fast Control Devicesmentioning

confidence: 99%

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Strategic Scheduling of Discrete Control Devices in Active Distribution Systems

Nouri

Soroudi

Keane

2020

IEEE Trans. Power Delivery

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The frequent actuation of discrete control devices (DCDs), e.g., on-load tap changers, drastically reduces their lifetime. This, in turn, imposes a huge replacement cost. Simultaneous scheduling of these DCDs and continuous control devices, e.g., distributed energy resources, is imperative for reducing the operating cost. This also increases the lifetime of DCDs and helps to avoid the sub-optimal/infeasible solutions. Considering the high cost of discrete control actions (DCAs), they may never be justified against the other options in a short scheduling horizon (SH). With a longer SH, their benefits over a long period justify DCAs. However, a shorter SH helps to hedge against the risk impelled by uncertainties. Here, the system future is modeled as a set of multi-period scenarios. The operator exploits a long SH, but solely applies the decisions made for the first period and waits for updated data to make the next decisions. This enables cost reduction by strategically applying DCAs prior to the time that they are inevitable, while avoiding them when unneeded. The proposed branch-and-cut-based solution methodology accurately deals with DCAs while applying some expediting heuristics. During the branching process, a globally convergent trust region algorithm solves the integer relaxed problems. BC Branch and cut CB Capacitor bank DCA Discrete controllable action DCC Discrete control cost DCD Discrete controllable device DER Distributed energy resource DSP Distribution scheduling problem LP Linear programming MILP Mixed integer linear programming MINLP Mixed integer nonlinear programming NLP Nonlinear programming OC Operation cost OLTC On load tap changer PDF Probability density function RES Renewable energy sources RHC Receding horizon control SH Scheduling horizon SOCP Second-order cone programming SVR Static voltage regulator SA Solution approaches A. Nouri (alireza.nouri@ucd.ie), A. Soroudi (alireza.soroudi@ucd.ie) and A. Keane (andrew.keane@ucd.ie) are with the

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Section: A Literature Reviewmentioning

confidence: 99%

Section: A Literature Reviewmentioning

confidence: 99%

“…A perturbed relationship between I, V and tap is given in (13). Matrices A and B are defined in (13) and (14), respectively.…”

Section: A Fast Control Devicesmentioning

confidence: 99%

Section: A Fast Control Devicesmentioning

confidence: 99%

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Strategic Scheduling of Discrete Control Devices in Active Distribution Systems

Nouri

Soroudi

Keane

2020

IEEE Trans. Power Delivery

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“…so that (12) and (14) are satisfied and so is (9). Remark 5: The convex approximation in (14) may cause a loss of optimality in the OPF problem. However, it helps to avoid that the phase angle of the voltages deviates too much from the base voltages, which is also not desirable.…”

Section: Stochastic Voltage Limitsmentioning

confidence: 99%

Stochastic Optimal Power Flow in Distribution Grids under Uncertainty from State Estimation

Picallo

Anta

Schutter

2018

2018 IEEE Conference on Decision and Control (CDC)

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The increasing amount of controllable generation and consumption in distribution grids poses a severe challenge in keeping voltage values within admissible ranges. Existing approaches have considered different optimal power flow formulations to regulate distributed generation and other controllable elements. Nevertheless, distribution grids are characterized by an insufficient number of sensors, and state estimation algorithms are required to monitor the grid status. We consider in this paper the combined problem of optimal power flow under state estimation, where the estimation uncertainty results into stochastic constraints for the voltage magnitude levels instead of deterministic ones. To solve the given problem efficiently and to bypass the lack of load measurements, we use a linear approximation of the power flow equations. Moreover, we derive a transformation of the stochastic constraints to make them tractable without being too conservative. A case study shows the success of our approach at keeping voltage within limits, and also shows how ignoring the uncertainty in the estimation can lead to voltage level violations.

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Adaptive algorithm for identifying OLTC position and its application on UHV voltage-regulating transformer differential protection

Zheng

Liu

et al. 2018

Int Trans Electr Energ Syst

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The voltage-regulating transformer (VRT) with on-load tap changer is specifically used to adjust the voltage on the medium-voltage side of the ultra-high voltage power transformer. In practice, during the process of on-load voltage regulation, it is difficult to acquire the tap changer's positon, which is necessary for the calculation of the VRT differential current. Therefore, a novel algorithm is proposed to identify the real-time turns ratio of the VRT, adaptively, according to the structure of the ultra-high voltage power transformer. On the basis of the real-time turns ratio, the adaptive differential current is calculated. Both theoretical analysis and simulation results indicate that the proposed algorithm can track and calculate the turns ratio accurately, thus preventing unbalanced currents during the tap-changing process. Moreover, the performance of the VRT differential protection is evaluated under inter-turn fault conditions. Simulation results verify that the proposed algorithm can overcome the disadvantages in the existing protection schemes.KEYWORDS differential protection, inter-turn fault, on-load tap changer (OLTC) position, ultra-high voltage (UHV), voltage-regulating transformer (VRT)

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Optimal Tap Setting of Voltage Regulation Transformers in Unbalanced Distribution Systems

Cited by 120 publications

References 17 publications

Strategic Scheduling of Discrete Control Devices in Active Distribution Systems

Strategic Scheduling of Discrete Control Devices in Active Distribution Systems

Stochastic Optimal Power Flow in Distribution Grids under Uncertainty from State Estimation

Adaptive algorithm for identifying OLTC position and its application on UHV voltage-regulating transformer differential protection

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