A control algorithm for Parallel Connected Offshore Wind Turbines with permanent magnet synchronous Generators (PCOWTG) is presented in this paper. The algorithm estimates the optimal collective speed of turbines based on the estimated mechanical power of wind turbines without direct measurement of wind speed. In the proposed topology of the wind farm, direct-drive Wind Turbine Generators (WTG) is connected to variable low-frequency AC Collection Grids (ACCG) without the use of individual power converters. The ACCG is connected to a variable low-frequency offshore AC transmission grid using a step-up transformer. In order to achieve optimum wind power extraction, the collective speed of the WTGs is controlled by a single onshore Back to Back converter (B2B). The voltage control system of the B2B converter adjusts voltage by keeping a constant Volt/Hz ratio, ensuring constant magnetic flux of electromagnetic devices regardless of changing system frequency. With the use of PI pitch compensators, wind power extraction for each wind turbine is limited within rated WTG power limits. Lack of load damping in offshore wind parks can result in oscillatory instability of PCOWTG. In this paper, damping torque is increased using P pitch controllers at each WTG that work in parallel with PI pitch compensators.

This paper presents a novel control algorithm for variable speed wind generators (VSWG), designed to provide support to grid frequency regulation. The proposed control algorithm ensures that VSWG ‘’truly’’ emulates response of a conventional generating unit with non-reheat steam turbine (GUNRST) in the first several seconds after active power unbalance. A systematic method of analysis and synthesis of the new control algorithm is described in detail.

In this paper, the frequency response metrics of interconnected electric power systems (EPS) of Slovenia, Croatia and Bosnia and Herzegovina (ENTSO-E SCB control block) is presented. In the upcoming period in this region significant integration of wind energy is expected. Increased wind integration has great impacts on EPS frequency response due to decreasing total system inertia. A frequency response metrics calculation in a short period after a disturbance occurred is essential for design of any further frequency control action. Comparison of local bus frequency and frequency of centers of inertia is in the focus of this work. The regional EPS of South East Europe (SEE) is modeled using PSS/E. Frequency response metrics calculations and plots are performed using Python simulation language.

A new control algorithm for Directly Interconnected offshore Wind Turbines with permanent magnet synchronous Generators (DIWTG) is presented. In the DΓWTG offshore wind park configuration, Wind Turbines with Permanent Magnet Synchronous Generators (WTPMSG) are directly connected to the offshore AC collection grid without using a power converter. The offshore AC collection grid is then connected, via a transformer, to the offshore AC transmission grid. In order to achieve maximum power point tracking, the (collective) speed of DΓWTGs is controlled by an onshore back to back converter. By measuring the active power and speed of the permanent magnet generators, wind speed at each turbine is estimated and used for calculation of the reference speed of WTPMSGs. Voltage control at the power converter side is performed in a way which allow the DΓWTGs to be operated at a constant V/f where the maximum resultant frequency at nominal wind speed is 16.67 Hz.

A modied control algorithm of a variable speed wind generator (VSWG) for supporting power system frequency stabilization is presented in this paper. A comparison of the performance of this algorithm with active power control algorithms of VSWGs for supporting power system frequency stabilization, as published in the scientic literature, is also presented. A systematic method of analysis of the modied control algorithm is described in detail. It has been shown that by using the modied control algorithm, the VSWG \truly" emulates the inertial response of a conventional steam-generating unit with synchronous generators during the initial/inertial phase of primary frequency control, following loss of active power generation when wind speed is between cut-in (i.e. 4 m/s) and rated speed (i.e. 12 m/s). By the inclusion of a signal proportional to the frequency deviation as a power reference to the torque controller feedback loop of the modied control algorithm, it is ensured that the contribution of the VSWG to frequency stabilization is independent of the initial wind speed. This independence is kept as long as the wind speed is above the cut-in wind speed and slightly below the rated wind speed (i.e. 12 m/s). One of the important features of the modied control algorithm, namely a near-proportiona relationship between the initial wind turbine speed and the maximum wind turbine speed variation during the inertial response, has been identied. The results of the analysis provide a solid basis for further research in the area of VSWG contribution to frequency stabilization.

In this paper the analysis of a General Electric Wind Turbine Control Model (GEWTCM) and comparison with a Generic Wind Turbine Control Model (GWTCM) is presented. The analysis is performed for the GEWTCM stationary state. Based on the analysis, a systematic method for the GEWTCM initializations as well as a methodology for calculation of the GEWTCM operating point in steady state are presented. It has been shown that, due to lack of limiting of the pitch controller and pitch compensation, uniqueness of solution for initial and steady state values of all GEWTCM state variables are ensured except for the state variables of the pitch controller and pitch compensation. Conclusions from the analysis can help in the implementation of the wind turbine control model in power system dynamic simulation software packages in applications with variable wind speed.

Abstract Model Reference Controller (MRC) for contribution of Variable Speed Wind Generators (VSWG) in inertial response of Electrical Power System (EPS) is presented and analyzed in this paper. MRC is synthesized based on a model of Generating Unit With non-Reheat Steam Turbine (GUNRST) thus enabling VSWG to emulate GUNRST response during the initial stage of dynamic frequency response ie inertial phase. Very important property of conventional steam generating units is that its contribution to inertial phase response is independent from the initial generating power. By using MRC in VSWG it is accomplished that in most common wind speed region (3-12 m/s) VSWG inertial support is almost independent from wind speed. Since in most EPSs VSWG replaces conventional steam generators, application of MRC algorithm provides that the characteristics of EPS in terms of inertial response are preserved, regardless of the growing trend of introducing VSWG. Evaluation analysis of the proposed MRC is performed on modified nine bus power system when VSWG with MRC is connected to one of the power system buses.

Povecanjem udjela proizvodnih jedinica na bazi obnovljivih izvora energije, među kojima su i vjetroelektrane (VE), znacajno se mijenja struktura i nacin pogona elektroenergetskog sistema (EES). U uvjetima znacajnog ucesca VE u EES, dolazi do smanjenja broja prikljucenih konvencionalnih proizvodnih jedinica, odnosno posljedicno do smanjenja vrijednosti ukupne inercije sistema i izmjena dinamickih karakteristika EES-a. U novije vrijeme je sve ucestaliji zahtjev za ucescem VE u primarnoj i sekundarnoj regulaciji frekvencije. Doprinos VE primarnoj regulaciji frekvencije može se ostvariti upravljajuci injektiranjem djelatne snage vjetrogeneratora koje je zasnovano na ''ekstrakciji'' njegove kineticke energije. Na taj nacin se postiže da VE u ovom režimu rada imaju slicne karakteristike kao i konvencionalne elektrane. U radu su, na osnovu pregleda literature, ukratko prezentirani osnovni algoritmi za upravljanje aktivnom snagom VE pri frekventnim tranzijentima. Opisane su i kljucne karakteristike predloženog originalnog algoritma upravljanja, kojim se emulira inicijalni frekventni odziv vjetrogeneratora. Karakteristike predstavljenog algoritma upravljanja su ilustrirane na osnovu simulacija na jednostavnom test sistemu.

In this paper is presented Model Reference Fuzzy-Neuro Text Matching System. By using user-friendly interface in the form of if-then rules, syntax and semantics rule base, and English word base, the input text has been transformed to an array of potentially important terms (entities). Entities, that are characterized with their names and attributes that have been extracted from the text, are inputs into the Fuzzy Inference System (FIS). The output from FIS is “term importance” for given text which is regarded as the coordinate of input text in term space. In order to simplify tuning of parameters of the FIS, FIS is transformed to neural network. Neural network parameters are adjusted offline using some reference knowledge that has been a prior given by some experts. Matching of the input text against other texts is performed using Euclidean norm in the term space. Due to the fact that output term base is organized in the term-wise form, text matching is simplified since it is performed only against those texts that the given term belongs to. By using user-friendly interface in the form of if-then rules, the overall system is open for future inclusion of new syntax and semantics rules.

In this paper it is presented the real time monitoring system of water flow in hydro power plants which is designed with virtual instrumentation software. Water flow through penstock has been measured by using flow sensor. Volumetric flow of excess water, in the case of emergency evacuation of water, has been calculated from position of control gates and water level. Relationship between the volumetric flow of excess water, position of control gates and water level has been a prior experimentally established and saved into look up table. Signals from position and level sensors have been used as inputs into the look up table. Entries into the look up table are interpolated using bilinear interpolation method and they are used for calculation of excess water flow. By using integration method with fixed step time, the volume of transmitted water through all outlets has been calculated. All necessary real time calculation, data presentation and data logging have been performed using virtual instrumentation software. With a proper application software organization and by means of digital communication real time measurement and presentation of results are ensured.

This paper has proposed Specific class of single input single output (SISO) Mamdani fuzzy logic proportional controllers (FLPC) with triangle input membership functions, output membership functions with the same area, the sum-product composition rule for inference and centroid of area defuzzifier for control of both stable and unstable SISO linear time invariant systems. The proposed FLPC in fact represents memoryless, nonlinear, locally Lipschitz mapping between its input and output. According to the Popov criterion for absolute stability, nonlinear part of the system must satisfy sector conditions. In this paper necessary and sufficient conditions have been determined, which must satisfy FLPC parameters in order for the memoryless function represented by FLPC to satisfy the sector conditions. Subsequently, using the Popov criterion, the sufficient conditions for absolute stability of feedback connected linear system and FLPC have been determined. Based on the results achieved, an optimization method for both parameters and decision rules of FLPC has been proposed using genetic algorithms.