Ioana Pisica

Optimal SVC placement in electric power systems using a genetic algorithms based method

The problem of improving the voltage profile and reducing power losses in electrical networks is a task that must be solved in an optimal manner. At present time, this optimality can be achieved by efficient usage of existing facilities alongside with installing FACTS devices. The Static VAr Compensator (SVC) was chosen for study as its maturity and acceptable costs make it more usable in practical applications than other FACTS devices This paper proposes a genetic algorithm that tries to identify the optimal location and size of an SVC. A multi-criteria function is developed, comprising of both operational objectives and investment costs. The computer program is run on a 13 nodes test system, assessing improvements in voltage profile and reducing power losses. The purpose of this study is to validate the solution method in order for it to be adapted for systems of higher dimensionality.

Optimal Distributed Generation Location and Sizing Using Genetic Algorithms

The paper proposes a comparison between nonlinear optimization and genetic algorithms for optimal location and sizing of distributed generation in a distribution network. The objective function consists of both power losses and investment costs and the methods are tested on the IEEE 69-bus system. The study covers a comparison between the proposed approaches and shows the importance of installing the right amount of DG in the best suited location. Studies show that if the DG units are connected at non-optimal locations or have non- optimal sizes, the system losses may increase.

Novel application of detrended fluctuation analysis for state estimation using synchrophasor measurements

The phasor measurement unit (PMU), with its ability to directly calculate synchronized positive sequence voltages and currents (magnitude and phase), offers a more current and accurate view of the power system compared to that provided by traditional measurements and state estimation (SE). However, the high-resolution data, provided at rates of 50 Hz and 60 Hz (dependant on nominal frequency), capture any transient or dynamic events occurring on the network, potentially distorting the intended steady-state view at various points of the power system. In this paper we propose the use of detrended fluctuation analysis (DFA) to detect and isolate such events for alternative investigation. Comparisons are made between the state estimator and installed PMUs on the high-voltage transmission system of Great Britain.

Parallel detrended fluctuation analysis for fast event detection on massive PMU data

Phasor measurement units (PMUs) are being rapidly deployed in power grids due to their high sampling rates and synchronized measurements. The devices high data reporting rates present major computational challenges in the requirement to process potentially massive volumes of data, in addition to new issues surrounding data storage. Fast algorithms capable of processing massive volumes of data are now required in the field of power systems. This paper presents a novel parallel detrended fluctuation analysis (PDFA) approach for fast event detection on massive volumes of PMU data, taking advantage of a cluster computing platform. The PDFA algorithm is evaluated using data from installed PMUs on the transmission system of Great Britain from the aspects of speedup, scalability, and accuracy. The speedup of the PDFA in computation is initially analyzed through Amdahls Law. A revision to the law is then proposed, suggesting enhancements to its capability to analyze the performance gain in computation when parallelizing data intensive applications in a cluster computing environment.

Simulation of power system substation communications architecture based on IEC 61850 standard

Changes in the wholesale electricity market alongside the difficulties in upgrading the transmission system have increased the complexity of power networks operations. This fact has placed heavier demands on developing new technologies to manage power systems reliably. Driven by the growing smart grid applications, ICT infrastructures are becoming more important for the communication of monitoring, control and protection information at both the local and wide area levels. IEC 61850 is a standard released by the International Electrotechnical Commission (IEC) for power utilities that can provide integrated and interoperable data communications. It defines communication between Intelligent Electronic Devices (IEDs) in substations and related system requirements. Although it was originally introduced for the automation of substations, the application of IEC61850 is expanding rapidly. In this paper, we present simulation and modelling of a typical power system substation communication infrastructure. Furthermore, the deployment of IEC 61850 for Wide Area Network (WAN) applications, such as Phasor Measurement Units (PMUs), will be investigated.

Performance evaluation of smart metering infrastructure using simulation tool

Future smart grids will require existing distribution networks to support novel distribution management system functionalities. Millions of smart meters will be deployed in the UK in near future. Vast amounts of data from such meters and other intelligent electronic devices (IEDs) in distribution network substations will require high speed communications. Such data will have to be concentrated at the local level before being transmitted to the control centre through different communication media. The performance of the underlying communication media should be evaluated to assure the required level of performance guarantees from the distribution network operators (DNOs) during the data transmission. Initially, an OPNET based Power Line Communication (PLC) simulation was verified using available experimental test results. Then a simulation study consisting of smart meters, concentrators and PLC links was used to evaluate the transmission time between local concentrators and smart meters for varying data sizes. Greater number of smart meters consumed higher bandwidth. This limitation was studied by varying the number of smart meters and concentrators connected to the PLC medium. The successful transmission rate for each configuration was also evaluated to confirm how many smart meters manage to send all the data to the concentrator within a specified time limit. Several other scenarios were used to evaluate the performance of the smart metering infrastructure.

Modeling and analysis of noise in power line communication for smart metering

Power line communication (PLC) has been widely used in the Smart Grid environment as it represents a low cost communication solution for distribution networks and more recently smart metering. However, its instability under noisy channel conditions requires careful simulations and modelling before implementing any PLC-based solution. Modelling physical characteristics of PLC using different simulation tools has been investigated in the past and is an ongoing research challenge. In this paper, the suitability of PLC for smart metering is tested in terms of scalability and performances under different noise conditions, by using discrete event simulations for a PLC model previously validated with experimental results under the EU-funded project HiPerDNO.

Implementation of Wide Area Monitoring Systems and laboratory-based deployment of PMUs

Power systems are operating in a more complicated condition and therefore encounter more challenges. If one part of a power grid becomes seriously out of synchronism with the rest, the whole network can become unstable and blackout may occur. In this regard, we need to use advanced and smart monitoring tools to quickly and reliably observe the changing state of the key electrical parameters in real time, take appropriate corrective measures and isolate faults. Phasor Measurement Units (PMUs) by employing satellite technology, offer a state-of-the-art Wide Area Monitoring System (WAMS) for improving power system monitoring, control and protection. In this paper, we present information about WAMS components and requirements as well as description of work carried out in Brunel University laboratory to develop and implement a synchronized measurement system.

Investigation of open standards to enable interoperable wide area monitoring for transmission systems

Nowadays, power systems face more challenging network wide issues with regard to ensuring secure and reliable operation. Therefore, having a wide area monitoring system is a vital need in order to detect problems and react on them as quickly as possible. An important component when providing wide area monitoring and control for transmission networks is the SCADA system, which connects the substations to the control center by polling data from Remote Terminal Units (RTUs). However, due to data rate limitations, the monitoring is relatively static and therefore infrequent. By using Phasor Measurement Units (PMUs) data can be provided in higher rates and with higher accuracy. Since different manufacturers exist in the market, standardization is the key for advancement of the connectivity and interoperability within the system. In the past, utilities used to employ proprietary protocols, which were specified by the product vendors. Gradually, it was decided to move towards open standards to provide an interoperable environment and improve modelling capabilities. Apart from PMU standards, in a typical power system several communication protocols exist and are required for transferring data and each of them covering certain domains and specific groups of data. The objective of this paper is to investigate the adoption, development and performance of the most common open standards to enable interoperable wide area monitoring systems.

A Standardised Modular Approach for Site SCADA Applications Within a Water Utility

Any large water treatment/production utility that employs autonomous plant as part of its processes will utilize supervisory control and data acquisition systems. These systems will generally be isolated from each other and will exist solely to serve the site they control and visualize. More often, they are delivered and developed organically through cost driven maintenance regimes that prioritize on process risk rather than asset lifecycles. In some cases, this has led to variations in installed software and hardware applications, not only across a business enterprise, but also down to a site level. This is usually based on favored products at the time of supply, and in turn requires a broader range of engineering skills to maintain and update. The previous adoption of a “fit and forget” model has also led to large areas of unsupported computer assets within an organization that further introduces “data risk.” As regulatory bodies start to impose stricter compliance measures on the water industry, so to the suppliers become more reliant upon their process data. This paper presents how a water utility has employed a modular approach and has set to standardize its SCADA assets across all business sectors. It reviews the hardware the systems are installed on, the software applications used to deliver the integration, and discusses how the software devices have been modeled and tagged in search of a common information model. All in line with their respective field assets. It also discusses some of the human factors surrounding the replacement of control systems.