Diego Issicaba

Distributed Energy Resources Impact on Distribution System Reliability Under Load Transfer Restrictions

Wind and solar power are well known intermittent power sources with high availability uncertainties. Hence, whenever they are integrated to distribution systems, these power sources can increase significantly the complexity of system operation. This paper presents an impact analysis of distributed energy resources integration on distribution systems, focusing mainly on reliability aspects. Therefore, an interesting algorithm to correctly determine the amount of capacity that may be transferred to other feeders is presented and discussed, taken into consideration the presence of distributed generation. The methodology is tested in a typical Brazilian distribution system, assuming the integration of a diesel-based combined heat and power unit, wind turbines, and solar panels. The results provide general insights regarding the benefits of applying distributed generation to alleviate load transfer restrictions.

Advanced Metering Infrastructure functionalities for electric mobility

The Smart Grid vision along with the future deployment of Electric Vehicles presents numerous challenges in terms of grid infrastructure, communication, and control. In this context, Advanced Metering Infrastructure solutions are envisioned to be the active management link between utilities and consumers. This paper presents a survey of potential AMI functionalities particularly developed to foster the large scale deployment of EV in Smart Grids. For this accomplishment, the concepts of Automated Meter Reading, Automatic Meter Management and Smart Metering are revisited. Furthermore, different EV charging approaches are outlined and included in the functionalities under the Vehicle-To-Grid framework. Finally, AMI use cases are described under the Vehicle-to-Home perspective.

Islanding operation of active distribution grids using an agent-based architecture

This paper presents a decentralized architecture for the islanding operation of distribution grids with large volume of distributed generation. This architecture involves the definition of network blocks which share the responsibility of frequency control. The control block abstraction was particularly designed to support the transition from regular grids to smart grids. In addition, the control schemes were developed using an agent-based paradigm. Hence, an agent-based simulation platform was implemented using libraries from the Java Agent Development Framework (JADE). The control schemes were evaluated using a test system with different sorts of distributed energy resources and modeled in the EUROSTAG environment. Simulation results show the effectiveness of the control architecture when different failure events are applied to the test system.

Adequacy and Security Evaluation of Distribution Systems With Distributed Generation

This paper presents an adequacy and security evaluation of electric power distribution systems with distributed generation. For this accomplishment, bulk power system adequacy and security evaluation concepts are adapted to distribution system applications. The evaluation is supported by a combined discrete-continuous simulation model which emulates the distribution system operation. This model generates a sequence of operation states which are evaluated from a steady-state perspective using AC power flow computations. Frequency and voltage stability are also assessed using dynamic simulation in order to verify the feasibility of islanded operation. Simulation results are presented for the RBTS-BUS2-F1 as well as an actual feeder from the South of Brazil. The results emphasize the need to consider adequacy and security aspects in the distribution system assessments, mainly due to the ongoing integration of distributed energy resources.

Real-Time Monitoring of Points of Common Coupling in Distribution Systems Through State Estimation and Geometric Tests

This paper presents an extended state estimation method which allows the identification of unexpected power injections at multiple points of common coupling (PCCs) of power distribution grids. The developed state estimator makes use of a three-phase network modeling where active and reactive power injection levels at PCCs are estimated and checked in real time with the values expected by the system operator. The estimation algorithm applies a sparse tableau formulation in which equality constraints are employed to model power injection assumptions at PCCs. The identification of unexpected power injections is then performed using a methodology based on normalized Lagrange multipliers and geometric tests. Simulations conducted on a modified version of the IEEE 34-node test feeder illustrate the accuracy and applicability of the proposed approach, fostering discussions regarding the future of real-time monitoring on power distribution systems.

Agent-Based System Applied to Smart Distribution Grid Operation

This chapter presents an agent-based architecturewhich was developed to support the smooth modernization of the power distribution grids. This architecture copes with the smart grid paradigm (ETP, 2008) and leads to changes in the grid operation rules, control and protection, as well as grid infrastructure. The main target of the architecture is to distribute decisions related to smart grid operation and to improve service adequacy and security. Hence, a complex environment simulation is designed to emulate the distribution grid operation and evaluate the impact of agent’s plans of action. The environment itself is modeled using a combined discrete-continuous simulation approach (Law, 2007) in which steady-state and dynamic aspects of the electrical behavior of distribution grids are represented in a detail way.

Multi-agent scheme to handle flexible loads on low voltage distribution grids

The large scale integration of electric vehicles and distributed energy resources on low voltage grids might cause serious problems related to, for instance, under/over voltages and line overloading. In order to cope with these problems, this paper presents a multi agent system (MAS) developed to dynamically schedule flexible loads on low voltage grids, preventing operation limit violations. Since different geographical positions of the loads in the grid will cause a different impact on the grid, load flow calculations are used to indicate operation limit violations. The application uses a decentralized algorithm which ensures similar chances of being scheduled to the customer loads using a priority scheme. A case study is carried out on a 70-bus feeder where electric vehicle loads are scheduled to prevent under voltages, showing the applicability of the approach.

Long-Term Impact Evaluation of Advanced Under Frequency Load Shedding Schemes on Distribution Systems with DG Islanded Operation

This paper presents a long-term impact evaluation algorithm to assess advanced under frequency load shedding (UFLS) schemes on distribution systems with intentional islanding of distributed generation (DG). The algorithm is based on a combined discrete-continuous simulation model which is utilized to verify the effect of the schemes on reliability indices such as the system average interruption frequency index, system average interruption duration index, and energy not supplied. Moreover, a polynomial neural network-based approach to advanced load shedding is implemented to support DG islanding in order to illustrate the applicability of the evaluation. Simulation results highlight the long-term effect of employing UFLS to support intentional islanding of DG using an actual network from the South of Brazil.

Impact evaluation of the network geometric model on power quality indices using probabilistic techniques

Distribution Power System performance assessment is usually based on continuity indicators and power quality measurements. Generally, these evaluations are performed using distinct mechanisms, where continuity is assessed by past network performance observations and/or predicted simulation, whereas power quality is evaluated using electronic measurements. In fact, the concepts of reliability and power quality are dissociated, mainly when distribution power system performance is assessed. However, the current diversity of loads and sources, with more sensitivity to voltage variations, requires a wider ranging of power system tools, which consider aspects of both continuity and power quality effects. Aiming for a distribution systems performance approach that considers both reliability and power quality issues into a unique evaluation framework, aspects related to the systems voltage as well as distorting phenomena affecting the voltage waveform need to be modeled. This paper proposes the impact assessment of network geometric model on power quality indices using simulation techniques. The main idea is to include a short-circuit model into a sequential Monte Carlo algorithm in order to assess power quality indices through estimates. The proposed methodology is applied to the IEEE test feeder with 34 nodes.

Rotational Load Flow Method for Radial Distribution Systems

This paper introduces a modified edition of classical Cespedes’ load flow method to radial distribution system analysis. In the developed approach, a distribution network is modeled in different complex reference systems and reduced to a set of connected equivalent subnetworks, each without resistance, while graph topology and node voltage solution are preserved. Active power losses are then not dissipated in the modeled subnetworks and active power flows can be obtained as a consequence of radiality. Thus, the proposed method preprocesses a series of variable transformations concomitant to an iterative algorithm using a forward-backward sweep to arrive at the load flow solution. The proposed approach has been tested using literature and actual distribution networks, and efficiency improvements are verified in comparison to Cespedes’ load flow method.