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This paper shares experiences acquired during the development of a fault location module (FLM) in a real Digital Fault Recorder and Phasor Measurement (DFRPM) device, which has been designed for the Itaipu utility, Brazil. Hardware and software aspects, as well as computational strategies and innovative solutions used to implement the FLM are addressed. The DFRPM fault location module (DFRPM-FLM) is validated by means of simulations in a Real-Time Digital Simulator, considering fault scenarios in high- and low-inertia systems. The case studies reveal that the adopted computational strategies resulted in a flexible and reliable DFRPM-FLM, which showed to be able to automatically estimate the fault location, without the need for human intervention. • The literature is scarce of works describing the implementation of real devices. • Experiences in building a real fault location device are discussed. • The used multi-method fault location approach showed to be promising. • Real-time hardware-in-the-loop simulations are carried out. • A satisfactory performance of the developed fault location device was obtained. [ABSTRACT FROM AUTHOR]

Electricity generation in Brazil heavily depends on hydroelectric power, making it vulnerable to fluctuations due to its reliance on weather patterns. Accurately forecasting water inflow into hydroelectric plants is vital for the National Electric System Operator to make decisions regarding the monthly scheduling and operation of the power system. In this paper, an evaluation of predicted flows for a 14-day horizon are evaluated for the Tucuruíhydroelectric plant, located in the Tocantins river in the North of Brazil. The temporal fusion transformer (TFT), long short-term memory (LSTM), and temporal convolutional networks (TCN) are compared. The findings demonstrate that the TFT is a more suitable alternative than LSTM and TCN models for predicting inflows for the next 14 days. The TFT model is hypertuned by Optuna to achieve an optimized structure (h-TFT). The h-TFT had a mean absolute percentage error of 13.1 and a Nash–Sutcliffe of 0.96, outperforming its initial version and even the bidirectional LSTM model in benchmarking. Based on the error results, h-TFT showed promise for flow forecasting and provides insights into decision-making processes in the Brazilian electricity sector. • Hypertuning the TFT improves its performance in median-term forecasting. • The h-TFT outperforms LSTM, and TCN models for time series forecasting. • Deep learning applied for scheduling operation of the electrical power system. • Energy planning based on the inflow forecasting of hydroelectric power plants. [ABSTRACT FROM AUTHOR]

• A new Angle Difference Controller to adapt the power order of embedded HVDC links. • Simulations with the proposed ADC in the official Brazilian Power System model. • Performance comparison of the ADC implemented in LCC HVDC link and VSC HVDC link. • A tutorial example to make it clear the appearance of loop flows in AC-DC systems. This paper discusses the power flow control of embedded HVDC links in the Brazilian grid, with special attention to the requirements of intermittent energy sources where frequent load changes are needed, including power reversal, and automated action is called for. Recently two North-South bipoles, 4000 MW each, ±800 kV, have entered into service, these being embedded in the grid and with separate receiving end converter stations. In this case "reverse" power flow is foreseen, but only on a seasonal basis when water flow is low at the North region. The increasing capacity in wind and solar energy, especially in the Northeast region and the possibility of a new embedded HVDC link to carry the surplus power from this region, call for an adaptable power setpoint in the DC links in order to avoid adverse effects as loop flows and increased losses. The paper investigates the use of angle difference control and proposes a new controller to mitigate those adverse effects. [ABSTRACT FROM AUTHOR]

• The system is a continuous real time PQ monitoring based on the concept of Digitally Enabled Substation Architecture or Substation 4.0 (SB4.0). • It presents a scalable architecture that allows the analysis of data from multiple substations. • It presents a practical implementation of the SB4.0 concept by proposing a novel multi-functional Substation Edge Device called here as PQMC (Power Quality Monitoring Center). • The system was installed in two substations that are part of the electrical Brazilian transmission grid. From the knowledge of the authors the system is one of the first PQ monitoring system using the concept SB4.0. • The PQMC receives voltage and current samples from a Merging Unit (MU), using the IEC 61850 Sampled Values (SV) format, and calculates various power quality parameters. • The system also provides a Data Logger application triggered by instantaneous Total Harmonic Distortion (iTHD) and by short duration voltage disturbance. • The Power Quality Monitoring and the Data Logger systems are software applications running in an industrial computer. • The System is time synchronized by GPS, providing time synchronized power quality parameters as well as waveform signals. • Results obtained from the proposed system was compared with commercial IED. • Experimental validation of the system in the laboratory and in the field. • This work is the result of a Research and Development Project with a power transmission company located in northern Brazil. • Modular architecture of the PQMC based on asynchronous queues is also a contribution of this work. This approach grants to the proposed IED a great scalability owing to the use of the single-producer multiple-consumers design pattern. • In the PQMC architecture, the signal processing routines of different channels are completely independent and do not depend on each other. • The proposed architecture allows for the modification of the PQMC features just by reconfiguring the software and without hardware changes, which is quite adherent to the SB4.0 concept. The growth of penetration of large blocks of inverter based renewable energy in transmission power systems may lower the power quality of these systems, especially with rising of harmonic and interharmonic distortion and voltage fluctuation. Poor Power Quality (PQ) can negatively affect the protection system and may cause premature aging of electrical equipment connected to the power system. Thus, real-time and continuous PQ monitoring can be of great value for operation, maintenance and expansion of the system. This paper presents a recently implemented real-time PQ monitoring system based on the concept of Digitally Enabled Substation Architecture or Substation 4.0 (SB4.0). The proposed PQ monitoring system receives voltage and current signal samples from a Merging Unit (MU) and calculates the various power quality parameters. Since the system uses the SB4.0 concept the power quality monitoring is a software application implemented in an industrial computer. Also, the system provides a Data Recording application, running as additional software task that provide oscillography triggered by instantaneous Total Harmonic Distortion (iTHD). This paper presents the architecture of the developed and implemented system as well as the field results gathered from a transmission system in the north of Brazil. [ABSTRACT FROM AUTHOR]

In this paper, the performances of one-ended and two-ended traveling wave (TW)-based fault location techniques in series compensated transmission lines (SCTLs) are thoroughly investigated, highlighting the impact of the series capacitors (SCs) and their associated overvoltage protection on such routines. To do so, a diversity of fault simulations were carried out on a realistic Alternative Transients Program (ATP) power system model of a 500 kV/60 Hz double-circuit SCTL located in the north region of Brazil. From the carried out studies, it is demonstrated that the two-ended algorithm is not impacted when the SCs are installed at the line ends, but the single-ended routines based on correlation functions are more affected by the SCs banks, even though some promising results may be obtained depending on their adjustments. • Novel sensitivity analyses of TW-based functions on series-compensated lines. • Investigation on the performance of one- and two-ended TW-based fault locators. • Analysis considering a realistic power system model with SCs, SVCs, DC lines etc. • Points out the need of new adjustments for one-ended applications in SCTLs. • Addresses the challenges and viability of using TW-based fault locators in SCTLs. [ABSTRACT FROM AUTHOR]

The medium-term optimization of hydro-thermal power generation systems is a non-linear, non-convex, and large-scale multistage stochastic problem. The primary approach used so far employs linearized or piece-wise linearized versions in a Stochastic Dual Dynamic Programming modeling. Due to their computational costs, no method so far has combined the non-linearities and non-convexities in a large-scale stochastic problem. This paper tries to narrow this gap with a novel combination of techniques by applying a Primal–Dual Interior Point Filter Line Search algorithm for large-scale non-linear programming (IPOPT package) in a Progressive Hedging algorithm with detailed individualized non-linear representations of the plants. It has been tested on the extensive Brazilian power system, comprising over 100 hydro-electric plants and 32 thermo-electric plants. The second objective is to include price elasticity in the demand modeling, and then test the hypothesis of negligible price elasticity of demand. The hypothesis does not pass this test. This is an important contribution since Brazil's official models have no price elasticity in their demand modeling. This problem has over six and a half million variables. It took about 10 h to process each case in a cluster with a standard 2016 32 processors and 200GB of RAM. • A novel combination of techniques • Applying an IPOPT package in a Progressive Hedging algorithm • With detailed individualized non-linear representations of the plants. • Applied to a large-scale Hydro-thermal Power Systems. • Tests the hypothesis of negligible price elasticity of demand-Proven not negligible. [ABSTRACT FROM AUTHOR]

This paper proposes a new methodological framework to support the decision of Brazilian distribution companies (DISCOs) when defining maximum demand contracts with the transmission system. The contract must be established one year ahead, and several uncertainties associated to loads, distributed generation (DG) and internal grid contingency events, should be considered. The optimal contracting decision should take into account the risk profile of DISCO's stakeholders and the interest of final consumers. To tackle these topics, an engineering-based approach is proposed in which a chain of four methods composes the final solution approach. To ensure realistic and tractable solutions, load and DG time series are decomposed into low and high frequencies to address the challenge of deriving long-term probabilistic forecasts for high-dimensional time series in high frequency. The proposed methodology considers exogenous long-term trend drivers (such as economic and climatic indices) in the probabilistic forecasts of loads and DG, as well as corrective actions to respond against contingencies in the power flow simulation. Results for a Brazilian DISCO show that the proposed probabilistic forecasts are adherent and tractable. Our case study corroborates the effectiveness of our approach to support DISCOs' decision and adjust their contracts based on pre-specified risk levels. • Four integrated methods to define long-term DSO-TSO demand contracts in Brazil. • A new method for simulating high-dimensional hourly load and DG time series in a long-term horizon. • A new array of quantile regressions to estimate and simulate conditional dynamic load curves. • A risk-averse optimization model to define the optimal demand contracting strategy of a distribution company. [ABSTRACT FROM AUTHOR]

This work addresses the maintenance workforce planning in electric power distribution utilities. A two-phase optimization procedure is proposed to consider the strategic (long-term) and tactical/operational (medium/short-term) planning. In the first phase (strategic planning), a bi-objective optimization problem is solved to locate depots and to size the number of repair teams at each depot. One of the objectives includes operating and capital expenses, while the other one is based on continuity indicators related to the interruption in the electrical energy supply. In order to solve this problem, we use a memetic algorithm which combines a metaheuristic with a mixed-integer linear programming (MILP) model. On the other hand, the second phase (tactical/operational planning) consists of solving other MILP model to determine, for each depot, the required number of electricians (now based on more detailed forecasts) and define their work schedules, minimizing the wage costs and hiring/firing expenses. The results show that a larger number of solutions can be found through the memetic algorithm compared to the purely metaheuristic approach. The proposed optimization algorithm is part of an innovative web-based system developed during a research and development project and it is now available for eleven Brazilian power distribution utilities. • The paper presents an innovative two-phase optimization algorithm for workforce planning not only in power distribution utilities but also in any other utilities that have field teams serving vast geographic regions (i.e., large transmission systems operators). • A two-phase optimization procedure is proposed to consider the strategic (longterm) and tactical/operational (medium/short-term) planning. In the first phase (strategic planning), a bi-objective optimization problem is solved to locate depots and to size the number of repair teams at each depot. This module uses a memetic algorithm which combines a metaheuristic with a mixed-integer linear programming (MILP) model. • The second phase (tactical/operational planning) consists of solving other MILP model to determine, for each depot, the required number of electricians (now based on more detailed forecasts) and define their work schedules, minimizing the wage costs and hiring/firing expenses. • The proposed algorithm is evaluated by means of a real case study related to the workforce planning problem for an electric distribution utility in Brazil (Energisa Sergipe). [ABSTRACT FROM AUTHOR]

• Vector Shift Relay islanding detection capability versus system stability; • The need of Vector Shift Relay standardization for its secure applicability; • A Vector Shift Relay adjustment procedure for grid-tied synchronous generators; • A case study on Brazil's anti-islanding commissioning for distributed generation. The increasing electricity demand has encouraged consumers to invest in distributed energy resources and, among these, synchronous generators fed by biogas. One of the main concerns over this is the possibility of these sources feeding a section of the grid while a loss of mains, known as islanded operation. To prevent it, distributed generators must have protection devices that can identify this loss of connection. Vector Shift Relays are one of the most popular methods for island detection applied to synchronous generators. However, an increasing concern on false tripping of these relays has led the Brazilian electricity regulatory agency to ponder about their removal. In this paper, a detailed analysis of the Vector Shift Relay operation and configuration is done and a new procedure to determine the relay threshold value is proposed, considering different power-load mismatches. It is shown that this protection device is quick to detect islanding when there is a power unbalance greater than 30% but it may risk false tripping if adjusted to a lesser power mismatch. Finally, a discussion is presented to show that there are issues with correctly using this device and still complying with current standards, and further investigations are recommended. [ABSTRACT FROM AUTHOR]