Vladimir Stanojevic

Decentralized Participation of Flexible Demand in Electricity Markets—Part II: Application With Electric Vehicles and Heat Pump Systems

Realizing the significant demand flexibility potential in deregulated power systems requires its suitable integration in electricity markets. Part I of this work has presented the theoretical, algorithmic and implementation aspects of a novel pool market mechanism achieving this goal by combining the advantages of centralized mechanisms and dynamic pricing schemes, based on Lagrangian relaxation (LR) principles. Part II demonstrates the applicability of the mechanism, considering two reschedulable demand technologies with significant potential, namely electric vehicles with flexible charging capability and electric heat pump systems accompanied by heat storage for space heating. The price response sub-problems of these technologies are formulated, including detailed models of their operational properties. Suitable case studies on a model of the U.K. system are examined in order to validate the properties of the proposed mechanism and illustrate and analyze the benefits associated with the market participation of the considered technologies.

Two-Stage Improved Recursive Newton-Type Algorithm for Power-Quality Indices Estimation

In the paper, a new improved recursive Newton-type algorithm (IRNTA) suitable for various measurement applications in the electric power systems is presented. Here, it is applied for power-quality (PQ) indices estimation according to the IEEE Standard 1459-2000. Basically, the algorithm is a recursive nonlinear estimator, improved with a strategy of sequentially tuning the forgetting factor. This approach generally improves the algorithm performance: immunity to random noise, accuracy, and the speed of convergence. The IRNTA considers the power frequency as an unknown model parameter and takes into account distortion of voltages and currents. Therefore, it is suitable for the real-time PQ monitoring. The algorithm has two stages. In the first stage, the input signal spectra and fundamental frequency are estimated, whereas in the second stage, the unknown PQ indices are calculated. To demonstrate the efficiency of the proposed algorithm, the results of computer simulations and laboratory testing are presented.

Digital Metering of Power Components According to IEEE Standard 1459-2000 Using the Newton-Type Algorithm

In this paper, a new two-stage Newton-type algorithm for the measurement of power components according to the IEEE Standard 1459-2000 is presented. To estimate their spectra and fundamental frequency, in the first stage, the current and voltage signals are processed, whereas in the second stage, the power components are calculated based on the results obtained in the first stage. The algorithm considers the frequency as an unknown parameter and simultaneously estimates it with the input signal spectrum. Through this, the algorithm becomes insensitive to frequency changes and the problem becomes non-linear. The algorithm performance is tested using computer-simulated and laboratory tests.

STLS Algorithm for Power-Quality Indices Estimation

This paper introduces a new two-stage, self-tuning least-squares digital signal processing algorithm for power-quality (PQ) indices estimation according to the power components and PQ indices definitions given in the IEEE Standard 1459-2000. The algorithm is based on the nonrecursive least error square technique accompanied with an tuning procedure, which generally improves the algorithm properties: the measurement range, the immunity to a random noise, convergence, and accuracy. The presented algorithm models typical signal distortions and it can be used for the real-time PQ indices estimation. In order to estimate signal spectra and fundamental frequency, current and voltage signals are processed in the first algorithm stage, whereas in the second stage, the power components and PQ indices are calculated based on the results obtained from the first stage. To demonstrate the efficiency of the proposed algorithm, the results of computer simulated and laboratory tests are presented.

Frequency and Power Components Estimation from Instantaneous Power Signal

In this paper, the problem of the simultaneous estimation of frequency and power components is investigated. It is solved through a new recursive estimator capable of estimating the unknown model parameters during severe dynamic changes in the system. By this, a simple nonlinear parameter model for the instantaneous power, taking into account the fundamental components of voltage and current, is used as a starting point for the power components and frequency estimation. In the model, the system frequency is considered as an unknown model parameter, and it is simultaneously estimated with other unknown parameters. This resulted in an efficient numerical algorithm for the measurement of power components, which is not sensitive to variations of the system frequency. This is an important achievement, which improves the accuracy of the method during network transients. The new estimator has been improved by the strategy for tuning its forgetting factor according to the system dynamics, and it is tested through computer simulations and by using data records obtained under laboratory conditions. The algorithm was developed for a single-phase system, and the approach might be easily extended to multiphase systems.

Synchronized Measurements-Based Algorithm for Short Transmission Line Fault Analysis

A new numerical algorithm for the analysis of single line to ground faults on short overhead transmission lines is presented in this paper. It is based upon synchronized sampling at two line ports, and an accurate fault model including the arcing phenomena and tower footing resistance at the fault point. The core of the algorithm is an efficient nonrecursive parameter estimation method. A dynamic arc model is included in the fault model to represent the arcs interaction with the external power network. The algorithm accurately estimates the arc voltage amplitude, tower footing resistance, and the fault location, simultaneously. The algorithm is derived in the time domain, and is based on the synchronized acquisition of currents and voltages at both line terminals. Case studies based on simulated data are presented to demonstrate the effectiveness of the new method. In particular, the sensitivity of the proposed algorithm to synchronization errors, harmonics, line capacitance, and fault resistance were explored with lumped, distributed, transposed, and untransposed line models.

Assessment of Frequency and Harmonic Distortions During Wind Farm Rejection Test

This paper proposes a new application of the self-tuning least squares (STLS) estimation algorithm for understanding transient processes during a rejection experiment at a wind farm site in Denmark. The problems of simultaneous estimation of frequency and harmonic distortion in a wind farm are investigated. An adaptive and robust application of the STLS algorithm is proposed to estimate the unknown parameters during the dynamic changes due to forced islanding conditions. Equipped with a self-tuning procedure, the algorithm is resistant to noise which significantly improves its accuracy. The system frequency is considered as an unknown model parameter and estimated simultaneously with fundamental and harmonic components. The outcome is an estimation method which is not sensitive to variations of system frequency. To demonstrate the efficiency of the proposed algorithm, a number of computer simulated tests are also presented. Several interesting results can be observed during the rejection experiment: the large deviations of three phase voltages and currents, the changes of total harmonic distortion, and variations of power system frequency.

Detection of Arcing Faults: Modelling, Simulation, Testing and Algorithms Aspects

A new adaptive numerical algorithm for overhead line protection is presented in this paper. It uses an advanced fault model taking into account the arcing phenomena at the fault location and an efficient parameter estimation technique. A dynamic arc model is included in fault modelling to represent the arc interaction with the transmission system. Performance of the proposed estimation technique is extensively verified at different arc model parameters. The algorithm is derived in the time domain and it is based on synchronized acquisition of currents and voltages at both line terminals. It is tested through computer-based simulations of a line connecting two active networks.

Value of integrating Distributed Energy Resources in the UK electricity system

Continuous connection of Distributed Energy Resources (DER) technology on a “fit and forget” basis may lead to inefficiently low utilization of generation and network assets. In order to mitigate this effect, a reappraisal of the technical, regulatory, and commercial frameworks that shape decisions on future network design, investment, operation, and pricing are required. The transition of distribution network operation from passive to active would facilitate cost effective integration of DER and an efficient evolution towards a low carbon electricity system. In this context, this paper summarizes the results from a range of quantitative studies on the UK electricity system that have been carried out to assess the benefits of active management of distribution networks.

Synchronised Measurements Based Algorithm for Long Transmission Line Fault Analysis

A novel numerical algorithm for the analysis of single line to ground faults on long overhead transmission lines is presented in this paper. The algorithm is an extension of previous work by the authors and takes into consideration the shunt capacitance of the transmission line, making it applicable to long overhead transmission lines. The algorithm utilizes synchronized data sampling from both line terminals and a non-recursive parameter estimation method. The algorithm was developed using an accurate fault model including arcing phenomena and tower footing resistance, and a dynamic arc model was included in the fault model used to test the algorithm. The algorithm was derived in the time domain and simultaneously estimates the arc voltage amplitude, tower footing resistance, and the fault location. The proposed algorithm was thoroughly tested using simulated fault cases. In particular, the sensitivity of the algorithm to fault resistance, harmonics, untransposed line models, and parallel lines was investigated.