S. St. Iliescu

Modern approaches in power system control

The structure and coordination of the electrical power system (EPS) are presented in this paper with respect to three concepts: system theory, systems analysis and multi-agent techniques. The above mentioned concepts are discussed approaching the EPS behaviour and functioning based on actual problems regarding the globalisation of the energy production and transportation, integration of different renewable sources of energy with the conventional power systems and the safety aspects of connecting the distributed generation to the interconnected large system.

Parity equations for fault detection and isolation

Sensors, actuators or physical components in engineering systems are often subjected to un-permitted or unexpected deviations from usual operating conditions. With a relatively small computing effort and with good results to unmeasured disturbances, the parity equations build for a specific process are proven to be very useful to provide fault detection residuals in order to identify the fault.

Process modelling for Load Frequency Control in power systems

Underlining first the principle of Load Frequency Control (LFC) according to the UCTE regulations this paper also presents simple continuous time models identified for the main hydro and thermal power generation units used by the LFC in Romanian Power System. Different models were proposed in previous articles but they are very complex for LFC studies. An experimental identification procedure based on deterministic methods with rectangular pulse sample signal is proposed to estimate the values of models parameters. These models can be used for tuning LFC systems as well as for building and setting up a real-time simulator for dispatcher training.

Load frequency regulation in power systems

This paper focuses on load frequency regulation, as a major function of automatic generation control (AGC) in the context of a versatile power system structure, environmental constrains and emerging new uncertainties. Generation units models are determined in order to build a control diagram used for load dispatch. The optimal parameters for the secondary controller were determined using a gradient descent algorithm.

A comparative analisys of FACTS devices implemented in the Romanian power system

The paper describes the dynamic behavior of STATCOM device and a SVC device connected in the National Grid and shows simulation results. The operation principle of the two devices will be presented. The simulations were made using specialized software Eurostag. Various operation scenarios were simulated in order to show the impact on the transmission power grid.

EVOLVED FUZZY CONTROL SYSTEM FOR A DRUM BOILER

Abstract Economic feasibility of a power plant requires smooth and uninterrupted plant operation in the face of varying electrical power demand. The feed-water system in a power plant is a major contributor to plant unavailability. The investigations about operation experiences of a power plant show that one of frequent causes of shutdowns is by violation of safety limits on the water level and is common at low operating power where the plant exhibits strong non-minimum phase characteristics. This paper presents a framework for addressing this problem based on a method of evolved control based on fuzzy model predictive control. Fuzzy model based fault detection methods are elaborated envisaging fault tolerant control. Results from validation of the evolved control system are presented. A new concept of modular evolved control system designed for a seamless and gradual integration into the existing distributed control system is proposed.

MODEL-BASED FAULT DETECTION AND ISOLATION OF THERMAL PROCESSES

Abstract The purpose of this model-based approach is the detection and isolation of sensors or other process components faults for a thermal process. One of the most powerful fault detection approaches is through parity equations. The applicability of the proposed method is illustrated on thermal plant in order to underline the advantages of this method. The model runs in parallel to the process, leading to symptoms with different sensitivities to a specific fault. After presenting the residual generator building method, a description of the thermal plant, the faults symptoms and FDI results are given.

Observers Approach Regarding Thermal Processes Fault Detection

Abstract Model based fault detection methods require, when possible, an analytical insight into the process dynamics, considering as a case study the model of a heat exchanger. Fault detection filters (a particular class of full order Luenberger observers) are used to generate directional residuals for the purpose of fault isolation. The paper proposes improved methods for fault isolation and a new unknown input observer with enhanced robustness (in the disturbance decoupling sense). Simulations for various scenarios sustain the conclusions