Analysis Of Voltage Reliability Of Microgrid On Offshore Platforms

With the development of the economic and the growing consumption of fossil energy on land, the energy shortage has become so increasingly remarkable in China that conventional power is unable to meet the demand. "Marine engineering", alleviating domestic energy demand to some degree, plays an important role for sustainable development and energy strategy. Micro-grid in offshore platform, with gas turbine power generation synchronous motor generator sets as its power generation device, is the main power supply to "marine engineering". It provides a variety of services for the offshore platform including power and heat supply, which achieves a step effective use of power to improve the comprehensive utilization of energy rate.Micro-grid in offshore platform is a nonlinear dynamic system with relatively large-scale and complex structure. Particularity of the marine circumstance leads a less voltage reliability and operation stability, which is directly related to the normal operation of large equipment's and marine engineering. Therefore, it is necessary to analysis and study the voltage reliability of the micro-grid. Considering some particularities of the offshore platforms micro-grid, this paper carried out the voltage reliability analysis from the perspective of the system voltage static and transient stability respectively. The overall framework and assessment program of voltage reliability in micro-grid have been proposed and designed in this paper. The main research content is as follows:(1)According to the isolated operation of offshore platform micro-grid, the static voltage reliability of an actual offshore platform micro-grid has been studied. Both eigenvalue index and L index were selected to identify the weak voltage node of the system.(2)The eigenvalue index, L index, classical PV curve and QV curve were used to assess the voltage reliability of the identified weak voltage node in the micro-grid system.(3)The results of the previous voltage static analysis were tested by simulating with PSCAD/EMTDC. Some typical faults in micro-grid system were simulated to study the voltage transient reliability.(4)Transmission line is a long-distance submarine cable in offshore platform micro-grid, whose capacitance effect is more remarkable compared with ordinary lines so that reactive power changes much and has greater impact on voltage reliability in micro-grid. The parameters of submarine cable have been reasonably reconsidered and the voltage stability has been analyzed.In this paper, power flow example was presented based on an actual offshore platform micro-grid, considering the difference between the submarine cable and ordinary cable. Relevant parameters were selected to calculate the value of index of voltage reliability in terms of power flow calculation result, and then voltage reliability of the system was assessed. System model was simulated to analyze the transient voltage reliability. The results showed that the accuracy and effectiveness of the proposed voltage reliability assessment program which enables efficient online monitoring for the actual operation of the marine platform micro-grid and provides some references in terms of power quality and the like.