Giuditta Pisano

DMS Cyber-Physical Simulation for Assessing the Impact of State Estimation and Communication Media in Smart Grid Operation

Energy management systems for the operation of distributed energy resources, distribution storage devices, and responsive loads will be embedded in distribution management systems (DMSs) as advanced functions that rely on accurate input data and fast communication signals. For a proper DMS design, the impact of the state estimation uncertainties and of the communication system delays should be evaluated. The paper presents an integrated software package for the cyber-physical simulation of DMS taking into account the accuracy of state estimation and measurements. The effectiveness of a wireless Wi-Max communication system has been tested on the rural Italian representative network produced by the research project ATLANTIDE. Results proved the need of cosimulation packages in modern distribution systems.

Optimal Allocation of Multichannel Measurement Devices for Distribution State Estimation

This paper proposes an optimization algorithm that is suitable for choosing the optimal number and position of the measurement devices in distribution state estimation (DSE) procedures used in modern electric distribution networks. The algorithm is based on the techniques of dynamic programming, and its goal is to guarantee both the minimum cost and the accuracy required for the measured data needed to operate management and control issues, such as energy dispatch and protection coordination. Both the uncertainty introduced by the measurement devices and the tolerance in the knowledge of the network parameters (line impedances) are taken into account in the proposed approach. The aggregation of the quantities to be measured in a few measurement points has been favored to reduce the overall cost of the measurement system. Random changes in the loads are considered to establish adequate reference conditions for the tests. Tests relevant to real distribution networks are presented to show the validity of the proposed approach. The results emphasize how both the influence of the tolerance on the network parameters and the cost of the measurement system can dramatically be minimized by suitably choosing the algorithm to be implemented to solve the DSE problem.

Advanced DMS to manage active distribution networks

The paper presents an advanced Distribution Management System capable to manage an active distribution network economically and safely. The DMS optimizes the power flows in the network, regulates the voltage profiles, acting on reactive flows and tap changers in substation, minimizes the energy losses, reconfigures the network, exploits storage devices and responsive loads in an integrated way. The optimization algorithm finds the optimal combination of such operation options to minimize system costs without causing violations of the technical constraints. The system costs include the energy losses, the cost of generation curtailment, the cost of reactive power, the cost of load shedding, and the cost of storages. The proposed method has been applied on a model test network to verify the validity of the approach.

Optimal Placement of Measurement Devices in Electric Distribution Systems

This paper proposes an optimization algorithm suitable to choose the optimal number and position of the measurement devices needed to operate management and control issues, such as energy dispatching and protection coordination, in modern electric distribution networks. The goal of the proposed procedure, which is based on the dynamic programming, is to guarantee at the same time the minimum cost and the accuracy required to the measured data. Both the random changes of the loads and the uncertainty introduced by the measurement devices are taken into account. An example, relevant to a real size distribution network, shows the validity of the proposed approach

Analysis of the Italian distribution system evolution through reference networks

This paper presents initial results of a three-year research project entitled ATLANTIDE, which is aimed at developing a comprehensive digital archive of reference models of Italian distribution networks, including forecasted load and generation development evolving towards future smart grid scenarios. Such reference network models and evolutionary scenarios should provide a useful benchmark for testing and comparing different control methodologies, distribution schemes and operation strategies for dealing with the new challenges caused by the envisaged widespread diffusion and integration of distributed generation, renewable generation and distribution storage devices. The paper focuses on the criteria adopted for defining a set of evolutionary scenarios for the reference networks, accounting for current drives and future trends, valuable to a wide range of the stakeholders of the distribution business.

Considering the uncertainty on the network parameters in the optimal planning of measurement systems for Distribution State Estimation

This paper proposes an optimization algorithm based on the techniques of the dynamic programming and suitable to choose the optimal number and position of the measurement devices in distribution state estimation procedures used in modern electric distribution network. The goal is to guarantee at the same time the minimum cost and the accuracy required to the measured data needed to operate management and control issues, such as energy dispatching and protection coordination. Both the uncertainty introduced by the measurement devices and the tolerance in the knowledge of the network parameters (line impedances) are taken into account in the proposed approach. Random changes of the loads are considered to establish adequate reference conditions for the tests. Tests relevant to a real size distribution network are presented to show the validity of the proposed approach. The results emphasize how the influence of the tolerance on the network parameters can be dramatically minimized by suitably choosing the algorithm to be implemented to solve the distribution state estimation problem.

Decoupling power system state estimation by means of stochastic collocation

This paper presents a new approach to the problem of system decoupling in a power-system state estimation problem. The complexity of power systems is growing, thus challenging the way measurements for state estimation are traditionally managed. Following a previous experience in defining a decentralized solution for state estimation, the authors here propose a decentralized dynamic state estimation method for a large-scale power system in combination with a procedure to automatically identify how and which state information to exchange for reconstructing the states starting from partial knowledge. In particular, the problem of selecting the variables that each observer has to estimate is partially solved within the framework of a stochastic approach, i.e., the so-called collocation method. An optimization algorithm based on dynamic programming is also developed to determine the optimal set of strongly coupled variables necessary for a sufficiently accurate estimation. The developed method is evaluated by applying to an IEEE test bus system.

Embracing an Adapatable, Flexible Posture: Ensuring That Future European Distribution Networks Are Ready for More Active Roles

The challenge for EU member states is to ensure the timely evolution of DNOs to their future, more active roles, which are necessary to make low-carbon societies a reality. While the corresponding regulatory actions will largely depend on the context and characteristics of the distribution networks within each member state, it is clear that incentivizing innovation should be key in this endeavor. Equally critical is defining the roles of potential future players and technologies in the provision of flexibility (e.g., consumers, aggregators, and storage) to prevent new business models being hindered by regulatory barriers. This transition of DNOs to DSOs in the next few years will certainly bring exciting new regulatory environments where the envisioned smart grids are likely to finally emerge.

Co-simulation of distribution active management and distribution state estimation to reduce harmful effects of inaccuracies

Active networks are distribution networks with generators, storage devices, and flexible loads subject to control. Distribution Management System (DMS) needs to know the state of the network to coordinate distributed energy resources and manage and control the system economically and safely. The distribution systems have a very large number of nodes but few measurements points. Ad hoc Distribution System State Estimators (DSSEs) are needed to provide to the DMS the estimated status of the network (starting from real measurements and historical data, e.g. pseudo-measurements). The quality of the estimates can seriously affect the system management. In this paper, co-simulation of DMS and DSSE is presented. The impact of the uncertainty of the DSSE results on DMS operation is investigated by applying the proposed procedure to representative examples derived from ATLANTIDE project.

Considering Voltage Dips Mitigation in Distribution Network Planning

Voltage dips are disturbances that undermine the quality of supply or, more precisely, the power quality perceived by the customers, often causing heavy economic damages to the end-users. Methods for mitigating voltage dips have been widely investigated in literature, but poor attention has been given to solutions that consider their mitigation at the planning stage. In previous works, the authors have proposed a distribution network planning methodology to deal simultaneously with the network design and the power quality. The optimization algorithm is able to find some convenient solutions to comply with power quality constraints. To reduce the expected number of voltage dips above a threshold established by regulators and to protect the customers, the planner is driven to perform specific actions, as the installation of custom power devices in particular nodes of the network. In this paper, an improved model of dynamic voltage restorer has been developed and implemented in the optimization methodology. Accordingly with this model the effectiveness of the compensation device has been evaluated with the aim at finding the most economical solution to voltage-dip problems. In the paper, examples are provided to showing the impact of voltage dips and their mitigation in distribution planning.