Optimal Placement of Phasor Measurement Units Using a Modified Canonical Genetic Algorithm for Observability Analysis

This paper proposes a method for optimal placement of synchronized PMUs （phasor measurement units） in electrical power systems using a MCGA （modified canonical genetic algorithm）, which the goal is to determine the minimum number of PMUs, as well as the optimal location of these units to ensure the complete topological observability of the system. In case of more than one solution, a strategy of analysis of the design matrix rank is applied to determine the solution with the lower number of critical measurements. In the proposed method of placement, modifications are made in the crossover and mutation genetic operators, as well as in the formation of the subpopulation, and are considered restrictive hypotheses in the search space to improve the performance in solving the optimization problem. Simulations are performed using the IEEE 14-bus, IEEE 30-bus and New England 39-bus test systems. The proposed method is applied on the IEEE 118-bus test system considering the presence of observable zones formed by conventional measurements.

Coal measure metallogeny:Metallogenic system and implication for resource and environment

Coal,coal measure gas,coal conversion to oil and gas,and coal-based new materials are reliable guarantees for stable energy supply and economic and social development in China.The coal-dominated resource endowment and the economic and social development stage determine the irreplaceable position of coal resources in the energy system.Coal measure resources,including aggregated or dispersed solids,liquid and gaseous multitype energies,and metal as well as nonmetallic minerals,are the products of multisphere interaction and metallogenetic materials generation,migration,and accumulation.Coal measures record rich deep-time geological information of transitional and terrestrial peat bogs,which is a crucial carrier to reveal ecosystem evolution,significant organic carbon sequestration,atmospheric O_(2)/CO_(2)variation,and wildfire events.Coal measure evolution is accompanied by the migration and transformation of various materials during diagenesis-metamorphism,forming differentiated coal compositions besides properties and various mineral resources in its adjacent strata.The enrichment condition,occurrence state,and separation potential are the premise for level-by-level use and efficient development of coal measure resources.Coal measure metallogeny is based on the metallogenic system of multiple energy and mineral resources in coal measures and their environmental effects.Fully understanding coal measure metallogeny is beneficial for promoting the coal transition from fuel to raw materials and strengthening its attribute of multiple mineral resources.The metallogeny comprises various aspects,including:(1)the symbiosis mechanism,co-exploration and co-mining conditions of various resources;(2)the source-sink system of ore-forming materials;(3)the differential carbon accumulation and hydrogen enrichment effect;(4)organic(coal and hydrocarbon)and inorganic(mineral)interactions;and(5)combination of minerals naturally enrichment during the metallogenic process and artificial enrichment during the ore processing process.The coal measure metallogeny belongs to the geoscience disciplines,and studies the types,formation,distribution,enrichment mechanisms,evaluation methods,and development strategies of resources related to coal measures.The key scientific problems include geological records related to mineral enrichment processes,metallogenic mechanisms,resource distribution,occurrence evaluation,and accurate development.Developing coal measure metallogeny is significant in improving the critical mineral metallogenic theory,revealing various deep-time earth systems and realizing the national energy transformation and high-quality development.