THIS PAPER FOCUSES ON PARAMETER IDENTIFICATION OF MESH DISTRIBUTION GRIDS. IN ORDER TO TUNE SECONDARY LEVEL CONTROLLERS, ACCURATE MICROGRIDS MODELS, IN TERMS OF TOPOLOGY AND IMPEDANCES VALUES, ARE NEEDED. FURTHERMORE, AN EFFICIENT ENERGY MANAGEMENT STRATEGY RELAYS ON THE CORRECT ESTIMATION OF THE LOAD BEHAVIOR CONSIDERING ONLY MEASURABLE SIGNALS. WE APPLY THE WELL KNOWN RECURSIVE LEAST SQUARES (RLS) METHODOLOGY TO IDENTIFY THE COMPLEX ADMITTANCES OF THE LINES BETWEEN, AND LOADS AT, NODES WHERE VOLTAGE AND CURRENT MEASUREMENTS ARE AVAILABLE. THE PROPOSED ALGORITHM HAS LITTLE COMMUNICATION REQUIREMENTS AS THE SIGNALS CAN BE SAMPLED AT LOW FREQUENCIES COMPARED WITH THE GRID STANDARD. THE RELATIVELY LOW COMPUTATION LOAD OF THE ALGORITHM MAKES IT SUITABLE FOR ON-LINE IMPLEMENTATION ON REAL TIME. THE MAIN CHARACTERISTICS OF THE METHODOLOGY ARE ILLUSTRATED WITH HELP OF SIMULATION EXAMPLES.

INVERTER BASED MICROGRIDS IMPLEMENTED WITH MORE THAN ONE GRID FORMING SOURCE CAN SUFFER OF, SO CALLED, CLOCK DRIFTS WHEN INACCURATE TIME MEASUREMENT IS PRESENT. CONSIDERING THAT THE MAIN CAUSE OF THIS PROBLEM IS THE, SLIGHTLY, DIFFERENT VALUE OF THE TIME REGISTER AT EACH CLOCK, THE SYNCHRONIZATION APPROACH SEEMS LIKE A NATURAL CHOICE EVEN WHEN ADDITIONAL HARDWARE FOR THE IMPLEMENTATION OF THE SOURCES MIGHT BE REQUIRED. WE EXPLORE SEVERAL ALTERNATIVES FOR IMPROVING SYNCHRONIZATION, UNDERSTOOD AS THE CLOCKS SHARING THE SAME VALUE FOR THEIR RESPECTIVE TIME REGISTER. THIS LEADS TO PROPOSE A CONSENSUS BASED ALGORITHM FOR SYNCHRONIZATION WITH RELATIVELY LOW COMMUNICATION AND COMPUTATION REQUIREMENTS. THE ANALYSIS IS COMPLEMENTED WITH SIMULATION EXAMPLES TO SHOW THE MAIN CHARACTERISTIC OF THE DIFFERENT ALGORITHMS.

THE INCREASING DEPLOYMENT OF RENEWABLE ENERGY SOURCES (RES) IN DISTRIBUTION CIRCUITS EMPHASIZES THE IMPORTANCE OF SMART GRIDS, UTILIZING DISTRIBUTED GENERATION (DG), CONTROL ACTUATION, AND COMMUNICATION TECHNOLOGIES. AMONG THESE TECHNOLOGIES, DISTRIBUTED PHOTO-VOLTAIC (PV) SYSTEMS SIGNIFICANTLY IMPACT REACTIVE POWER INJECTION AT THE ROOT NODE, NECESSITATING CONTROL OF SUB-STATION POWER FACTOR. THIS PAPER PRESENTS A SIMPLE AND EFFECTIVE CONTROL STRATEGY FOR ACHIEVING REACTIVE COMPENSATION AND POWER DEMAND CONTROL IN MEDIUM-VOLTAGE DISTRIBUTION CIRCUITS. THE PROPOSED STRATEGY UTILIZES A DISCRETE-TIME CONTROL LAW TO DISTRIBUTE REACTIVE POWER INJECTION BETWEEN THE SUB-STATION AND DG UNITS, WHILE ALSO REGULATING OVERALL POWER DEMAND THROUGH ELECTROLYTIC HYDROGEN PRODUCTION AND FUEL CELL INJECTION. UNLIKE TRADITIONAL LOCAL APPROACHES, THIS SOLUTION ADDRESSES THE PROBLEM GLOBALLY, ALLOWING INSTALLED HARDWARE TO ACHIEVE CONSENSUS ON COMPENSATION NEEDS FOR THE ENTIRE CIRCUIT AND ENHANCE PREDICTABILITY OF AGGREGATED POWER DEMAND. THE EFFECTIVENESS OF THE PROPOSED ALGORITHM IS SUPPORTED BY A MATHEMATICAL PROOF OF THE CLOSED-LOOP SYSTEM?S CONVERGENCE. PERFORMANCE EVALUATION IS CONDUCTED THROUGH A CASE STUDY ON A 116-NODE DISTRIBUTION CIRCUIT WITH SIGNIFICANT RES PRESENCE. THE STUDY DEMONSTRATES THE EFFICIENT REGULATION OF REACTIVE POWER AND POWER DEMAND ACHIEVED BY THE PROPOSED CONTROL STRATEGY IN DISTRIBUTION CIRCUITS WITH HIGH RES PENETRATION. THIS CONTRIBUTION IS INSTRUMENTAL IN INTEGRATING AND MANAGING RENEWABLE ENERGY SOURCES WITHIN THE GRID, ENSURING STABILITY AND RELIABILITY.

THIS PAPER DEALS WITH THE PROBLEM OF POWER SHARING IN DC MICRO-GRIDS IN MESH TOPOLOGY WITH MULTIPLE ACTIVE BUSES. WE FORMALLY ANALYZE THE FEEDBACK LOOP COMPOSED BY THE MICRO-GRID AS A MULTI-AGENTS PROCESS, THE DC GENERATION UNITS AS ACTUATORS, THE DISTRIBUTED ARBITRARY LOADS AS DISTURBANCES, AND A LINEAR CONSENSUS BASED CONTROL STRATEGY, IN ORDER TO CHARACTERIZE ITS PERFORMANCE IN TERMS OF SECONDARY LEVEL CONTROL OBJECTIVES AS POWER SHARING AND MEAN VOLTAGE REGULATION. BASED ON EXISTING CONSENSUS CONTROL STRATEGIES, THE NOVELTY OF THIS APPROACH RELAYS ON THE POSSIBILITY OF COMPARING THE PERFORMANCE OF DIFFERENT CONTROLLERS THROUGH NUMERIC INDICATORS. FURTHERMORE, THE CHOSEN CONTROL STRATEGY IS NOT NECESSARILY DERIVED AS THE LAPLACIAN MATRIX OF AN UNDIRECTED GRAPH. IN THIS WAY, THE PROPOSED STRATEGY CAN BE TUNED TO ACHIEVE OPTIMAL BEHAVIOR IN TERMS OF CONVERGENCE SPEED, DISTURBANCES REJECTION, OR COMMUNICATION LINKS REQUIREMENTS. FURTHERMORE, BY DOING THIS WE ARE ABLE TO PROVE THAT THE TRADITIONAL DROOP CONTROL STRATEGY DOES NOT NECESSARILY ACHIEVE THE DESIRED OBJECTIVES IN MESH TOPOLOGY. THEREFORE, WE FOCUS ON THE CONSENSUS DYNAMICS OF THE CLOSED LOOP SYSTEM, DERIVING SIMPLE TEST TO CONCLUDE ON ITS BEHAVIOR, AND TO PROPOSE A LINEAR MATRIX INEQUALITY (LMI) BASED PROCEDURE TO VERIFY THE REGION OF VOLTAGE DEVIATIONS AT WHICH THE CONTROL OBJECTIVE CAN BE ACHIEVED. FINALLY, THE RESULTS OF THE PAPER ARE ILLUSTRATED THROUGH A SIMULATION EXAMPLE.

THIS PAPER PRESENTS A DETAILED TIME DOMAIN SIMULATION OF A SYNCHRONOUS GENERATOR CONNECTED TO AN INFINITE BUS THOUGH A TRANSMISSION LINE WITH SERIES CAPACITORS, FOR THE PURPOSE OF ANALYZING THE CAUSES AND EFFECTS OF SUBSYNCHRONOUS RESONANCE. TO MITIGATE THE SERIOUS DAMAGE THAT THIS PHENOMENON MIGHT CAUSE TO THE GENERATION UNIT SHAFTS, A SUPPLEMENTARY CONTROL OF THE SYNCHRONOUS GENERATOR EXCITATION SYSTEM, AND THE NGH DAMPING SCHEME ARE ANALYZED. THE EFFECTIVENESS OF THESE MITIGATION METHODS IS VERIFIED BY NUMERICAL SIMULATIONS ON MATLAB, BASED ON RUNGE-KUTTA ALGORITHMS.

THE CONTROL OF MICROGRIDS AT SECONDARY HIERARCHICAL LEVEL OFFERS MULTIPLE CHALLENGES. WHEN THE ENTIRE MICROGRID IS SEEN AS A MULTIPLE-INPUT-MULTIPLE-OUTPUT (MIMO) SYSTEM AND THE VOLTAGE SOURCE INVERTERS (VSI) CONNECTED AS CONTROL ACTUATORS, DISTRIBUTED CONTROLLERS HAVE BEEN PROPOSED TO INDEPENDENTLY ACHIEVE ACTIVE POWER SHARING, REACTIVE POWER SHARING, FREQUENCY RESTORATION, OR VOLTAGE REGULATION AROUND NOMINAL VALUES. HERE WE ADDRESS THESE ISSUES SIMULTANEOUSLY IN GENERIC SINGLE PHASE MESH-MICRO-GRIDS WITH ARBITRARY NON-LINEAR LOADS, IN ORDER TO DERIVE FORMAL CONDITIONS THAT CAN BE USED TO CHECK IF A GIVEN CONTROLLER ALLOWS TO REACH ALL FOUR MENTIONED CONTROL OBJECTIVES. THE PAPER IS COMPLEMENTED WITH A SIMULATION EXAMPLE WHERE THE MAIN CHARACTERISTICS OF THE PROPOSED METHODOLOGY CAN BE SEEN.