Power System

We present our findings from a study to evaluate the feasibility of a radioisotope power system (RPS) combined with active cooling to enable a longduration Venus surface mission. On-board power with active cooling technology featured prominently in both the National Research Council's Decadal Survey and in the 2006 NASA Solar System Exploration Roadmap as mission-enabling for the exploration of Venus. Power and cooling system options were reviewed and the most promising concepts modeled to develop an assessment tool for Venus mission planners considering a variety of future potential missions to Venus, including a Venus Mobile Explorer (either a balloon or rover concept), a long-lived Venus static lander, or a Venus Geophysical Network. The concepts modeled were based on the integration of General Purpose Heat Source (GPHS) modules with different types of Stirling cycle heat engines for power and cooling. Unlike prior investigations which reported on single point design concepts, this assessment tool allows the user to generate either a point design or parametric curves of approximate power and cooling system mass, power level, and number of GPHS modules needed for a "black box" payload housed in a spherical pressure vessel. Input variables include altitude, pressure vessel diameter, payload temperature, and payload power on Venus. Users may also specify the number and type of pressure vessel windows, use of phase-change material for additional (time-dependent) payload cooling, and amount of (rechargeable) battery power for peak power demand operations. Parameter sets that would enable a Venus surface mission with fewer than 16 GPHS modules were identified. Thus, the study provides guidance for design practices that might enable a long-duration Venus surface mission with an attainable quantity of 238 Pu, and with achievable operating parameters. 1 TABLE OF CONTENTS 1. INTRODUCTION .

This paper presents an effective algorithm to locate Single Line to Ground (SLG) fault at a transmission line. Post fault voltages and currents from both substation terminals were
used as the input parameters to the algorithm. Discrete Fourier Transform (DFT) was used to extract the magnitudes and phase angles of three phase voltages and currents. The modeling of the transmission line along with the algorithm was performed using Matlab/Simulink package. The results of fault location for SLG faults along the transmission line demonstrated the validity of the algorithm used even for high resistance earth fault.

April, 10 th Poster -sewage treatment This process diagram illustrates the series of steps and machinery for sewage treatment and purposes of recycled water. The process begins with the collection of sewage from the households, factories and etc. by sewage system. Then, at the first stage of sedimentation, the raw sewage is simply screened the grit and large objects for disposal by coarse screens, and the remaining liquid flows into the primary sedimentation tanks whose purpose is removing the raw sludge. At the following stage, the aeration tanks treat the effluent by compressed air. Afterwards, through the sedimentation of mixed liquor in final settling tanks, Class B/C recycled water is produced for restricted agricultural and landscape reuse and large amount of discharged water is disposed in tertiary treatment that focuses on disinfection with chlorine and ultra violet light. In this stage, there is also some activated sludge returning to previous aeration tanks for resettling. Besides, both primary and final settling tanks produce wastewater sludge that is digested in another professional treatment system. After the tertiary step, the Class A recycled water is used for three main purposes: indirect potable (drinking) reuse, industrial and domestic reuse (non drinking) and agricultural reuse. To sum up, the sewage treatment system does not run complicatedly, but it is essential for each resident to live in a pristine and comfortable environment.

Questo libro è un'analisi completa e approfondita del potere della stupidità, e quindi di riflesso anche sulla stupidità del potere e dell'autorità in tutte le sue forme. Il volume contiene vari saggi su queste bizzarre divinità, una raccolta di oltre 300 citazioni brevi d'autore per offrire un'ampia panoramica sull'argomento e una selezione completa di più di 1000 aforismi, massime, pensieri, invettive, anatemi, provocazioni e riflessioni tratte dall'intera produzione di Carl William Brown, che coprono gli anni dal 1992 al 2013. Poiché la tematica è estremamente complessa vi è inoltre una chiara prefazione, degli aforismi introduttivi, una breve introduzione che prepara ai vari saggi sull'argomento, e dopo il corpus centrale, vi sono ancora degli aforismi conclusivi, una postfazione con ulteriori analisi delle spinose problematiche e infine una serie di utili links a risorse varie presenti in rete. Per arricchire il tutto sono poi state inserite anche diverse decine di immagini. Per concludere dobbiamo sempre ricordare che la stupidità potrà anche essere un dono di Dio, ma, come diceva il santo Papa Karol Wojtyla, non bisogna di certo abusarne, anche perché, come ci ricorda Aristotele, la giusta misura è sempre un'ottima virtù.

The augmentation in electricity demand, power system privatization as well as efficacy of renewable resources has paved the way for power system companies and researchers to exploit the field of grid connected distributed generation (DG) and its issues, islanding being a dominant one. Several research works have been conducted to mitigate the issues of islanding detection (ID). In context of this, the paper gives a comprehensive review of islanding issues, standard test systems, criteria and shifting of research trends in islanding detection methods (IDMs). The significant contributions pertain to categorization of IDMs, evaluation of non-detection zone (NDZ) for each test system, disquisition on evolution and advancement of IDMs and its comparisons based on criteria such as NDZ, run on time, nuisance tripping percentage, applicability in multi DG system and implementation cost to draw out the strength and shortcomings of individual methods that will come to aid to the companies or researchers for establishing the applicability and appropriateness of such method for their concerned domain.

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The power systems protection laboratory is designed to directly apply theory learned in lectures to devices that will be studied in the laboratory. Power system protection is concerned with protecting electrical power systems from faults within the network by isolating the faulted components so as to leave as much of the remaining electrical network operational as possible. Moreover, by properly protecting the system components from overloading, the probability of fires and other catastrophic and expensive system failures can be minimized.

In understanding power protection, it is necessary to understand what is actually being protected. Providing superior protection is essential in mitigating the effects of disruptions on system stability. As such, it is essential for power engineers to understand the concepts and practices of underlying power protection.

The creation of a Power System Protection Lab at Palestine Technical University gives students the opportunity to gain some real-world experience in protection. Moreover, a laboratory of this type facilitates educational opportunities. It also provides numerous additional benefits such as research. The overall objective of this project is to test devices in the laboratory, conduct experiments on them, and prepare a laboratory manual.

1 Resumen-Se expone el desarrollo de 4 fases de análisis para el sistema eléctrico de potencia IEEE-30 buses, contemplando desde su modelado y simulación utilizando el software ETAP, la redacción de un plan de mantenimiento mediante el análisis de flujos de potencia, la mejora del sistema para el caso de mayor demanda y el cálculo de corrientes de corto circuito.

High penetration of renewable energy sources such as wind generation in microgrids (MGs) causes fluctuations of power flow and significantly affects the power system operation. This can lead to severe problems, such as system frequency oscillations, and/or violations of power lines capability. With the proper control, superconducting magnetic energy storage (SMES) is able to significantly enhance the dynamic security of the power system. In a SMES system, the power conditioning system (PCS) is the crucial component that directly influences the validity of the SMES in the dynamic control of the power system. This paper proposes the use of an improved SMES controller for the stabilization and control of the power flow of wind-hybrid MGs. In this sense, the design and implementation of a novel high performance PCS scheme of the SMES is described. Moreover, a detailed model of the SMES unit is derived and a novel three-level control scheme is designed, comprising a full decoupled current control strategy in the d-q reference frame and an enhanced power system frequency controller. The dynamic performance of the proposed systems is fully validated by computer simulation.

The problem of power system reinforcement is addressed from the point of view of overall system reliability and revenue only. A probabilistic function representing the loss of revenue due to service interruption is proposed as a measure of the global performance of the system and is taken as a criterion for reinforcement. A technique based on the sensitwity of the proposed function to the forced outage rates of system components is proposed to carry out the reinforcement. Examples are given to illustrate the technique. They show that parallel lines are not, in general, the best reinforcement.

This paper describes new matrix transformations suited to the eficient calculation of critical eigenvalues of large scale power system dpamic models. The key advantage of these methods is their ability to converge to the critical eigenvalues (unstable or low damped) of the system almost independently of the given initial estimate. Matrix transforms such as inverse iteration and S-matrix can be thought as special cases of the described method. These transforms can also be used to inhibit convergence to a known eigenvalue, yielding better overall eficiency when finding several eigenvalues.

Currently, power systems (PS) already accommodate a substantial penetration of DG and operate in competitive environments. In the future PS will have to deal with large-scale integration of DG and other distributed energy resources (DER), such as storage means, and provide to market agents the means to ensure a flexible and secure operation. This cannot be done with the traditional PS operation. SCADA (supervisory control and data acquisition) is a vital infrastructure for PS. Current SCADA adaptation to accommodate the new needs of future PS does not allow to address all the requirements. In this paper we present a new conceptual design of an intelligent SCADA, with a more decentralized, flexible, and intelligent approach, adaptive to the context (context awareness). Once a situation is characterized, data and control options available to each entity are re-defined according to this context, taking into account operation normative and a priori established contracts. The paper includes a case-study of using future SCADA features to use DER to deal with incident situations, preventing blackouts.

Recent improvements in fuel cell technology along with an increasing demand for small generator units have led to renewed interest in dispersed generation units. This work demonstrates a methodology for deploying dispersed fuel cell generators throughout a power system to allow for more efficient operation. A detailed study of the system losses and sensitivities on Eastern Washington system as part

Proposed ship-based long-range electromagnetic guns require input energies greater then 100 MJ, at peak powers in excess of 50 GW, and at average power in the tens of megawatts. This paper describes a conceptual pulsed-power system for driving these types of guns. A generic design was developed based on state-of-the-art power-supply, capacitor, and switching technologies. Results of modeling and parametric studies are presented, and key issues that impact system size and configuration are explored. An assessment is made of the feasibility of integrating this type of system into an electric-drive ship.

Technology advancement for renewable energy resources and its integration to the distribution network (DN) has garnered substantial interest in the last few decades. Integrating such resources has proven to reduce power losses and improve the reliability of DN. However, the growing number of these resources in DN has imposed additional operational and control issues in voltage regulation, system stability, and protection coordination. Incorporation of various types of distributed generators (DG) into DN causes significant changes in the system. These including new fault current sources, new fault levels, a blinding effect in the protection scheme, reduction in the reach of relays, and decrement in the detection of lowlevel fault currents for existing relays. Such changes will jeopardize the effectiveness of the entire protection scheme in the DN. This research aims to propose a robust protection scheme in which the relay coordination settings are optimized based on the network layout. The potential impacts of DGs on the DN are mitigated by utilizing a user-defined overcurrent-based relay characteristic to obtain the minimum operating time while satisfying protection coordination constraints. A hybrid optimization algorithm based on Metaheuristic and Linear Programming that has the capability to attain the optimal solution and reduces computational time is proposed in this work. The performance of the proposed technique is tested on radial DN integrated with microgrid (MG). The results obtained show the proposed technique has successfully reduced the relay operating time while meeting the protection coordination requirements for dynamic operating modes of a network.

The power system network is becoming more complex nowadays and it is very difficult to maintain the stability of the system. Today's enhancement of technology makes it possible to include new energy storage devices in the electric power system. In addition, with the aid of power electronic devices, it is possible to independently exchange active and reactive power flow with

The paper introduces a concept for integration of substation IED data, primarily coming from digital protective relays (DPRs) and digital fault recorders (DFRs). Modern substations are equipped with different types of IEDs. DFRs are traditionally used to capture data from various events and disturbances in the power system that may need to be analyzed. Most of the modern IEDs such as digital relays, power quality meters, and sequence of event recorders can offer data recording function that is quite similar to that of DFRs. In some recent substation designs there are cases where DFR function is replaced by an equivalent function provided by DPRs. There are also cases when both DFRs and DPRs are used and configured to record the same events. In this case records from DPRs are used as a redundant source for event analysis. The paper addresses main requirements for integration of substation data: communication and automated IED data retrieval, unifying event data file formats, verification of event data content, and proper handling of the system configuration parameters. Examples of substation data integration using the proposed concept are discussed through expansion of an existing DFR data integration and analysis system and through introduction of data coming from different substation IEDs. Digital simulator was used to evaluate the concept in the example with multiple IED types.

An integrated approach of the radial basis function neural network (RBFNN) and Takagi-Sugeno (TS) fuzzy scheme with genetic optimization of their parameters has been developed in this paper to design intelligent adaptive controllers for improving the transient stability performance of power system. At the outset this concept is applied to a simple device such as the thyristor controlled series capacitor (TCSC) connected in a single-machine infinite bus power system and is then extended to the interline power flow controller (IPFC) connected in a multimachine power system. The RBFNN uses single neuron architecture and its parameters are dynamically updated in an online fashion with the TS-fuzzy scheme designed with only four rules and triangular membership function. The rules of the TS-fuzzy scheme are derived from the real or reactive power error and their derivatives either at the TCSC or IPFC buses depending on the device. Further, to implement this combined scheme only one coefficient in the TS-fuzzy rules needs to be optimized. The optimization of this coefficient, as well as the coefficient for auxiliary signal generation, is performed through genetic algorithm. The performance of the new controller is evaluated both in single-machine and multimachine power systems subjected to various transient disturbances. The new genetic-neuro-fuzzy control scheme exhibits a superior damping performance as well as a greater critical clearing time in comparison to the existing PI as well as RBFNN controller with updating of its parameters through the extended Kalman filter (EKF). Its simple architecture reduces the computational burden, thereby making it attractive for real-time implementation.

It has been veri"ed that a controllable series capacitor with a suitable control scheme can improve transient stability and help to damp electromechanical oscillations. A question of great importance is the selection of the input signals and a control strategy for this device in order to damp power oscillations in an e!ective and robust manner. Based on Lyapunov theory a control strategy for damping of electromechanical power oscillations in a multi-machine power system is derived. Lyapunov theory deals with dynamical systems without inputs. For this reason, it has traditionally been applied only to closed-loop control systems, that is, systems for which the input has been eliminated through the substitution of a predetermined feedback control. However, in this paper, we use Lyapunov function candidates in feedback design itself by making the Lyapunov derivative negative when choosing the control. This control strategy is called control Lyapunov function for systems with control inputs. Also, two input signals for this control strategy are used. The "rst one is based on local information and the second one on remote information derived by the single machine equivalent method. : S 0 0 0 5 -1 0 9 8 ( 0 1 ) 0 0 0 9 9 -1

surge arresters have strategic importance and a noble mission to provide guard for the power transformer (equipment of greater cost in a substation, which has many artisan-made parts in its construction, larger manufacturing times, larger difficulties to repairing, etc.), high-voltage circuit-breaker, the installations and their associated equipment in a substation. This paper presents a philosophy adopted for implementing renewal of surge arresters in an optimized way, looking for correspondences between power transformer failures and surge arresters, aiming at getting excellent results and economic attractiveness, as subsidies for asset and planning managers to take decisions on technological evolution.

Linear Programming (LP) is a widely used tool for solving many linear/non-linear power-system optimization problems such as transmission planning, constrainedsecurity dispatch, optimal power flow, emergency control, etc. Variants of simplex-based methodologies are generally used to solve the underlying LP problems. In this paper an implementation of the newly developed Dual Affine (DA) algorithm (a variant of Karmarkar's interior point method) is described in detail and some computational results are presented. This algorithm is particularly suitable for problems with a large number of constraints, and is applicable to linear and nonlinear optimization problems. In contrast with the simplex method, the number of iterations required by the DA algorithm to solve large-scale problems is relatively small, generally between 20 -60, irrespective of problem size; this feature makes the DA method very fast in practical applications. The DA algorithm has been implemented considering the sparsity of the constraint matrix. The normal equation that is required t o be solved in every iteration is solved using a preconditioned conjugate gradient method.

Electricity metering plays a crucial role for all the commercial transactions on the energy market. Thus, an accurate evaluation of the performance of the electricity metering equipment is required not only in the reference operating conditions but also in the presence of disturbances affecting the power systems. As regards this matter, this paper analyzes the main aspects related to the

In this paper the behavior of the power supply system of a typical Light Railway Transportation System (LRTS) subjected to overvoltages of atmospheric origin is analyzed, with the purpose to determine the optimum location of the surge arresters. A complete model of the whole power system has been developed and the transients have been simulated with the electromagnetic code PSCAD-EMTDC.

This paper presents a decision support technique to help decision makers study the influencing factors in the design of a hybrid solar-wind power system (HSWPS) for grid-linked applications. These factors relate mainly to political and social conditions, and to technical advances and economics. The Analytic Hierarchy Process (AHP) is used to quantify the various divergencies of opinions, practices and events that lead to confusion and uncertainties in planning HSWPS. The trade-offhisk method is used to generate multiple plans under 16 different futures and obtain the corresponding trade-off curves. Unlike the traditional 2-D simulation, a novel modeling of a trade-off surface in 3-D space is presented where the knee set is determined using the minimum distance approach. Robust and inferior plans are segregated based on their frequent occurrence in the conditional decision set of each future and hedging analysis to reduce risk is performed in order to assign alternati5.e options in case risky futures occur.

This paper presents a modelling and simulation approach for determining the optimal degree-of-hybridisation for the drive train (engine, electric machine size) and the energy storage system (battery, ultra capacitor) for a medium-duty truck. The results show that the degree-of-hybridisation of known medium-duty hybrid electric trucks is close to the optimal degree-of-hybridisation using the methods as described in this paper. Furthermore, it is found that the Li-ion battery is from an energy and power density as well as cost point of view the most preferable energy storage system.

The transformation of the European infrastructure creates considerable system security challenges. GRID is a joint effort of six European research organizations to achieve consensus on the key issues involved by ICT related vulnerabilities of power systems in view of theses challenges. GRID has recently issued a preliminary Road Map for future research in the area, grounded on a survey on the position of the European industrial and research communities. The survey assessed the challenges raised and the research needs in this perspective. This paper reviews the conception process for the Road Map and provides motivations for the way it is structured. It also overviews the three areas of investigation of the Road Map: understanding the impact of risk and adapting society and organisations, developing risk and vulnerability assessment and upgrading control architectures. The focus is on the needs and the challenges within each area and the main objectives of the Road Map.

This paper presents a output tracking design for regulating the load voltage of the electric power system. Based on a model of electric power system proposed by Dobson and Chiang (1988), the saddle-node bifurcation and Hopf bifurcations were observed (Wang, et al, 1994) by treating the reactive power as system parameter. Those bifurcations were found to lead to the appearance of the dynamic or the static voltage collapses of the power systems. In construct to the state feedback design at the bifurcation point via the tuning of the Static Var Compensator as proposed in (Saad, et al, 2005), a sliding mode control (SMC) scheme using SVC was employed in this study to construct a load voltage tracking design control law for regulating the load voltage and hence providing the stability of electric power systems. The numerical simulations demonstrated that the proposed control scheme not only could provide the regulation of the load voltage but also prevent and/or delay the appearance of bifurcation phenomena and chaotic behavior.

This paper presents a comprehensive report on the performance of a 350 kW concentrator solar photovoltaic power system (PVPS). When installed in September 1981, it was the largest in the world at the time and is the only large concentrator photovoltaic (PV) power system in operation. The system has performed remarkably well and has met or exceeded most of its design goals. The paper briefly summarizes the system design, fabrication and installation phases, and deals in great detail with the performance, including the problems and failures experienced over a period of the past 7 years. The long term performance of this system clearly shows that large PV systems are indeed reliable sources of power with minimum operation and maintenance requirements. The PVPS operation is continuing. The system has operated in several different modes which include standalone and co-generation with diesel generators. It is now connected to the utility grid and operates in the peak power tracking mode. In the very near future, the system will have the additional capability of being directly coupled to a 350 kW electrolyzer to produce hydrogen.

some specific features: very long transcription units, deregulated termination, and transcription of non-coding satellite repeats. Here, based on the modern view on a role of RNA interference machinery in regulation of genome expression, we suggest a mechanism of initiation of satellite DNA transcription and offer a novel interpretation of the 'classical' hypothesis that sought to explain the significance of widespread transcription during oocyte growth.

The societal challenges of the 21st century are profound and wide ranging. Basic needs such
as food, housing, mobility, health, and energy will become even more acute as the world
population exceeds nine billion. The demand for sustainable development will require
redefined engineering cutting-edge skills and ever reaching hands-on experience to navigate
these needs to a standard level. The power sector is on the cusp of a technology breakthrough
with a number of promising developments coming on string. A concerted drive to solve
challenges of the energy trilenma: energy access, affordability and sustainability coupled with
rapid technological change that spored tech firms. Constant power supply is the hallmark and
the bedrock of any developed economy. Today, 60% to 70% of the Nigerian population have
no access to electricity. One hundred million Nigerians representing 60% of its population,
have no access to grid electricity and those who do, experience extremely unreliable supply.
This present power crisis will persist unless the government diversifies the energy resources
in domestic, commercial and industrial sectors and adopts new available technologies to
reduce energy wastage and to save cost. The need for diversified sources of power supply has
naturally become a germane issue with the nation now planning to opt out of monocultural
profiles. Recent innovations are already booming the power sector, enabling the emergence
of “the prosumer,” energy consumer who produces their own electricity taken for example
the tech such as solar photovoltaic (PV) , energy storage and smart metres. The use of
biomass as an innovation in clean energy and power has proven itself efficient.
Simultaneously, providing a way to produce electricity and reduce health hazards. The
establishment of mini-hydro stations is a pathway to enhance access to electricity for
Nigeria’s increasing population. In all, aiding the society and improving engineering
education.

This paper deals with load frequency control of an interconnected reheat thermal system considering battery energy storage (BES) system. Area control error (ACE) is used for the control of BES system. Time domain simulations are used to study the performance of the power system and BES system. Results reveal that BES meets sudden requirements of real power load and very effective in reducing the peak deviations of frequency and tie-power and also reduces the steady state values of time error and inadvertent interchange accumulations.

In this paper we analyse the Women’s and Feminist Movement (WFM)’s representation of work and power relations. We state that these are challenging the labour relations and the formal system of work by means of opening up new discursive approaches and innovative possibilities in terms of collective action. We will illustrate this through an analysis of the WFM’s discourses about work and gender in Spain between 2009 and 2012. We will discuss how the WFM’s interpretative frames are reshaping the notion of work, how their subjects of work displace the hegemonic and classical workers of trade unions, and how their collective action is transforming the place where representation about work occurs. We draw on power theories and representation approaches to show that the WFM is shaping new forms of work claims, which empower feminist networks and voices.

This paper presents an application of the steady state network equivalents and expert system for voltage and reactive power (VAR) control in large-scale power systems. A steady state network equivalencing technique is used to construct the "three tier" subsystem which is adequate to solve voltage violation problems. An expert system utilises the sensitivity tree method to select the optimal set of control actions to alleviate the voltage problem. The expert system was developed using the VP-EXPERT system shell. VP-EXPERT interacts with the power system analysis software providing analysis of the network sensitivity matrix and data for the knowledge base. Practical application of the developed expert system is demonstrated on the example of the HydroElectric Commission (HEC) power system of Tasmania, however the proposed approach is not limited by the system size.

Electricity interruption gives rise to a complete disorder in the society and is therefore unappreciated and highly criticized. Consequently, it becomes a great concern for national and/or private energy companies to conduct their power systems under severe requirements. These companies are asked to ovoid failures that induce power oscillation, voltage drop and high frequency deviations because these phenomena can produce the loss of the system integrity by rapid voltage collapse or any transient stability mechanism. New technology alternatives such as FACTS (flexible alternative current transport systems) can positively support conventional control systems such as PSSs (power system stabilizer), AVRs (automatic voltage regulator) and TGs (turbine governor). But at the same time, it is to recognize that power system control becomes more complicate and requires suitable global strategies. The paper deals with this problem and aims to show that UPFC is a suitable device in particular ...

This work deals with the state estimation and diagnosis of nonlinear systems with application to power systems. Dynamic modeling is performed using an index 1 property and decoupling techniques. New methods of state estimation, based on Extended Kalman Filter including a sliding window of measurements, are proposed to improve the robustness and accuracy. A new convergence study based on Lyapunov function and conditioning of the observability matrix is proposed to ensure the convergence of the observers. A combination of extended Kalman filter with moving horizon and the version with unknown input is considered to ensure the monitoring task. Performances of the proposed approaches were evaluated by numerical simulations of IEEE power system test.

The increasing influence of wind power in the power system operation has caused the power system operators to include wind power plants in the control of the overall power system, both in steady-state and transient operation. Therefore, the grid connection requirements of the power system operators involve wind power systems. Low voltage ride-through requirement is probably the most demanding grid connection requirement to meet, at least from the point of view of the wind energy conversion system. In presence of grid voltage dips, the low voltage ride-through compliance produces a mismatch between the generated active power and the active power delivered to the grid. The management of this mismatch supposes a challenge for the wind energy conversion system. In this work, a control scheme for the back-to-back neutral-pointclamped converter is proposed. Under grid voltage dip, the controllers for generator-side and grid-side converters work concurrently to meet the low voltage ride-through requirement by storing the active power surplus in the inertia of the generator and keeping constant the dc-link voltage. Simulation results verify the proposed control scheme.

In this paper, an advanced control system for the optimal operation and management of isolated power systems with increased renewable power integration is presented. The control system minimises the production costs through on-line optimal scheduling of the power units, taking into account short-term forecasts of the load and the renewable resources. The power system security is supervised via on-line security assessment modules, which emulate the power system frequency changes caused by pre-selected disturbances. For each of the above functions, a number of techniques have been applied, both conventional and AI based. The system has been installed in the dispatch center of Crete since June 1999, and is under evaluation