Load shedding scheme with under‐frequency and undervoltage corrective actions to supply high priority loads in islanded microgrids

Nascimento, Bruno de Nadai; Souza, Antônio Carlos Zambroni de; Costa, João Guilherme de C.; Castilla, Miguel

doi:10.1049/iet-rpg.2018.6229

Cited by 20 publications

(23 citation statements)

References 35 publications

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“…For simplicity, this paper considers the same set of available actions for all states of the environment. According to (8) for each state, ten actions are suggested that five actions are considered for the frequency agent and five actions for the voltage agent.…”

Section: Actionsmentioning

confidence: 99%

“…While high number of DGs can increase the MG availability when an error occurs on the main grid side in the islanded mode, the uncertain power output of renewable power resource like PV and wind turbine generator (WTG) makes the control of voltage and frequency of MG a challenging work, which needs more effort and new adaptive control mechanisms [6,7]. Without a strong and high-efficiency control method, in this condition, the frequency and voltage of the microgrid may reach undesirable values [8].…”

Section: Introductionmentioning

confidence: 99%

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Assessing the Use of Reinforcement Learning for Integrated Voltage/Frequency Control in AC Microgrids

2020

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The main purpose of this paper is to present a novel algorithmic reinforcement learning (RL) method for damping the voltage and frequency oscillations in a micro-grid (MG) with penetration of wind turbine generators (WTG). First, the continuous-time environment of the system is discretized to a definite number of states to form the Markov decision process (MDP). To solve the modeled discrete RL-based problem, Q-learning method, which is a model-free and simple iterative solution mechanism is used. Therefore, the presented control strategy is adaptive and it is suitable for the realistic power systems with high nonlinearities. The proposed adaptive RL controller has a supervisory nature that can improve the performance of any kind of controllers by adding an offset signal to the output control signal of them. Here, a part of Denmark distribution system is considered and the dynamic performance of the suggested control mechanism is evaluated and compared with fuzzy-proportional integral derivative (PID) and classical PID controllers. Simulations are carried out in two realistic and challenging scenarios considering system parameters changing. Results indicate that the proposed control strategy has an excellent dynamic response compared to fuzzy-PID and traditional PID controllers for damping the voltage and frequency oscillations.

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Section: Actionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessing the Use of Reinforcement Learning for Integrated Voltage/Frequency Control in AC Microgrids

2020

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“…However, inverter based autonomous microgrids have low effective inertia and fail to regulate the frequency under severe fault conditions. A Monte Carlo simulation to continuously monitor load flow for the verification of the frequency and the voltage of all buses to design a global and local strategies of load shedding is presented in [29]. However, the authors focused only on the steady state analysis, and the transient response of the microgrid from grid connected to island mode was not addressed.…”

Section: Introductionmentioning

confidence: 99%

Real Time-Based under Frequency Control and Energy Management of Microgrids

2020

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In this paper, an efficient under frequency control and the energy management of a distributed energy resources (DERs)-based microgrid is presented. The microgrid is composed of a photovoltaic (PV), double-fed induction generator (DFIG)-based wind and diesel generator with critical and non-critical loads. The system model and the control strategy are developed in a real time digital simulator (RTDS). The coordination and power management of the DERs in both grid-connected and islanded operation modes are implemented. During power imbalances and frequency fluctuations caused by fault or islanding, an advanced automatic load shedding control is implemented to regulate and maintain the microgrid frequency at its rated value. One distinct feature implemented for the load shedding operation is that highly unbalanced critical loads are connected to the microgrid. The diesel generator provides the required inertia in the islanded mode to maintain the microgrid rated frequency by operating in the isochronous mode. The International Council on Large Electric Systems (CIGRE) medium voltage (MV) test bench system is used to implement the DERs and their controller. The proposed control approach has potential applications for the complete operation of microgrids by properly controlling the power, voltage and frequency in both grid-connected and island modes. The real time digital simulator results verify the effectiveness and superiority of the proposed control scheme in grid connected, island and fault conditions.

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“…In the same way, the authors of [25,26] proposed some alternatives for the management resources problems to maximise the power supply in MGs operating in islanded conditions. A load shedding scheme to under-frequency and under-voltage corrective actions implemented inside the load flow algorithm is proposed in [27]. Furthermore, the latter addresses the necessity of a central agent able to make decisions about MG's operation, including generators' setpoints.…”

Section: Introductionmentioning

confidence: 99%

Centralised secondary control for islanded microgrids

Nascimento

Souza

Marujo

et al. 2020

IET Renewable Power Generation

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Electric power systems have undergone substantial changes in their operation. The higher penetration of renewable resources, demand response capability, and generators operating via droop control at the distribution level are the main features resulting in the microgrid concept. Microgrids must operate connected or islanded from the main grid, ensuring reliability and quality in the supply of energy in both operating scenarios. In this sense, the secondary control becomes essential in the system's resilience, since it is responsible for restoring the frequency and voltage within acceptable values. This study proposes a unified frequency and voltage secondary controls for microgrids operating in islanded mode. For this sake, a modification in the load flow algorithm considering a Jacobian matrix takes place, enabling a sensitivity analysis to give the adjustments in the set point of generators. The help of the Levenberg-Marquardt method improves the convergence in the modified load flow. All generators are continuously considered in this process, regarding their capabilities and relative control sensitivities concerning the operation point restoration. The proposed methodology is validated in a modified IEEE-37 node test feeder, showing the efficacy of the centralised secondary control under different scenarios of renewable generation penetration and load levels.

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Load shedding scheme with under‐frequency and undervoltage corrective actions to supply high priority loads in islanded microgrids

Cited by 20 publications

References 35 publications

Assessing the Use of Reinforcement Learning for Integrated Voltage/Frequency Control in AC Microgrids

Assessing the Use of Reinforcement Learning for Integrated Voltage/Frequency Control in AC Microgrids

Real Time-Based under Frequency Control and Energy Management of Microgrids

Centralised secondary control for islanded microgrids

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