D. Kottick

Battery energy storage for frequency regulation in an island power system

Large battery energy storage (BES) facilities may provide significant dynamic operation benefits for electric utilities. One area in which a BES facility could be useful is the frequency regulation requirement. This feature is significantly important for island power systems. The purpose of this paper is to quantify the effects of a 30 MW battery on the frequency regulation in the Israeli isolated power system. The study was performed on a single area model representing the whole power system and containing a first order transfer function that represented the BES performance. >

Optimization of load shedding system

An optimization algorithm is presented for an underfrequency load shedding system which is composed of several stages that are tripped at preset frequencies. The optimization of this system is considered with respect to a cost function that includes a dynamic part, which is the integral of the deviation from nominal frequency, and a static part which is the total load shedding. The optimization is constrained by the requirement of minimum allowed frequency and limitation on the total load of the shedding system. A projected gradient method is used for the solution, and analytic expressions for the partial derivatives are used to simplify the computation. Results of applying the optimization to a model of the Israeli power system are given together with a study of the cost parameters. >

HT-SMES operating at liquid nitrogen temperatures for electric power quality improvement demonstrating

We have developed and tested a laboratory scale High-T/sub C/ Superconducting Magnetic Energy Storage (HT-SMES) system with storage capacity of up to 1.2 kJ. It was designed to improve the power quality for a consumer supplied by 3-phase standard commercial electric power grid at a consumer power of up to 20 kW. This SMES is based on a high-T/sub C/ superconducting coil with a ferromagnetic core, immersed in liquid nitrogen at 65 K to provide efficient thermal contact with the coolant. We also developed a cryogenic DC-DC converter based on low resistance power MOSFET transistors, providing low losses in the stored energy and high operational efficiency. The power conditioning capability of our HT-SMES was proved, and compensation of voltage drops in the electric grid was successfully demonstrated.

Another stabilized generator model for three phase sinewaves

A new three dimensional oscillator for generating three phases of sinewaves is derived. The model is similar to the previous ones (Ref. 1 and 2) in enabling an undistorted stabilized generation of sinewaves. It possesses certain advantages in comparison to the previous models. The oscillator appears as a viable model for representing synchronous generators in a simplified manner in the simulation of power systems.

Operational and economic benefits of battery energy storage plants

Abstract Battery Energy Storage Plants (BESP) may provide significant dynamic operational and economic benefits to electric utilities. BESPs are composed only of static elements, hence their response to changing conditions in the power system is very fast. This paper analyses both the operational and the economic benefits of a BESP designed to supply spinning reserve and to reduce the extent of the under frequency load shedding that follows forced outages of large generating units. The analysis of the operational benefits was performed on a single area model representing the whole power system. The economic benefits were calculated with the aid of a long term generation expansion computer program and a daily operation simulation program.

Use of a three-phase oscillator model for the compact representation of synchronous generators

A recently suggested three-phase oscillator model system is developed further. The resulted model, although it is relatively simple and merely of a seventh order, represents fairly accurately the features and the dynamic behavior of a regulated synchronous generator (the simulated results on a digital computer are compared to measurements on a 2.2-kVA generator system). The model, in spite of its demonstrated simplicity, embraces a fully three-phase dynamics which includes variations directly at the line frequency. The three-phase oscillator signals represent in the model the components of a rotating magnetomotive force. Magnetomotive forces are regarded as the main variables, since the regulation in an experimental generator system, which is employed for comparison, is achieved by controlling the rotor current via a current source.

Comparison of Methods and Algorithms for Accurate Frequency Trend Estimation Following Emergency Transients in Power Systems

A short ieview of methods and algbrlthms for power line frequency parameters estimation and prediction during einergency transients in power systems is given. Simulation results. obtained from processing experimental data. are shown. Some further improvements i n DSP methotls and algorithms are proposed and discussed.

An introduction to dynamic security of supply in the Israeli power system

The main objective is to identify and implement measures which would prevent the interruption of electricity supply to the consumer in the face of severe disturbances in the power system (e.g. transmission line faults, forced outages of generating units, etc.). This aim is achieved by assessing the impact of different contingencies on the power system and enhancing the security through preventive or corrective control actions. The security of the system is described by a Security Index which is a scalar value based on several attributes of system behaviour.<<ETX>>

New DSP Method for Investigating Dynamic Behavior of Power Systems

A new, simple Digital Signal Processing (DSP) method for investigating dynamic behavior of Power Systems is considered, which combines Integrating Zero Crossing (IZC) and Quasisynchronous Sample Interpolation (QSI). It offers accurate (about 0.001%) and fast (30-40 ms) tracking, estimating and predicting the actual power-line frequency and its deviation, as well as spectral harmonic components of the actual power line voltages and currents with high accuracies (0.02%-0.05%), due to almost complete elimination of aliasing and leakage effects. The results of a computer simulation of this method and of many real-life experiments are given and explained. The proposed method (IZC, QSI) has been compared to other DSP methods used for Power System investigation and applied in Underfrequency Relay Protection (URP); Load Shedding and Restoration (LSR); Acquisition, Monitoring, and Control (AMC); Diagnostics and Quality Analysis (DQA); and in other industrial applications.

A NEW DSP-METHOD FOR FREQUENCY AVERAGE ESTIMATION IN POWER SYSTEMS

ABSTRACT The paper represents a new DSP method for estimating the average deviation of the power grid frequency and its rate of change. This estimation is important for monitoring and control in power system. The frequency is an important parameter for control of generating units, especially during dynamic transients caused by sudden imbalances between load and generation. The method is based on the iterative algorithm (known as Ostrogradskys second algorithm), in which only 4-5 periods of the line signal are sufficient to achieve 0·01% estimation accuracy. A short description of this method, the computational procedure and its implementation, including its simulation on a PC are given. Further improvements of this method, including its combination with other DSP-methods, are also discussed and illustrated by experimental data.