Reliability Analysis And Risk Assessment Of Auxiliary Power System Of Peaking Power Plant

Main peaking-load power plant plays an important role in a power grid with increasing peak-valley difference and its operation reliability, which are of great significance to the safe and stable operation of power grid. The start/stop and power regulation of the equipments are more frequent than those in ordinary power plants, therefore the requirements to the reliability of the equipments and systems are much more rigor. This paper carries out a comprehensive and systematic research on the reliability calculation methods, risk assessment methods and reliability improvement measures for auxiliary power system of peaking natural gas power plant.This paper adopts symbolic dynamics method to describe reliability and risk description for auxiliary power system. Based on this description, risk evaluation method is constructed, and Life Cycle Cost(LCC) is used as constraints to evaluate the effect of reliability improvement methods.Firstly, this paper selects a set of equipment reliability indicators applicable to the reliability calcution of auxiliary power system. The reliability model of power components and operation components of auxiliary power system are built respectively based on the Markov equations. The power components are simulated by a three-state Markov model which contains normal, failures and planned outages state, while the operation components are simulated with normal, planned outages, unplanned outages and malfunction state. The probability calculation formulas are derived according to the relationship between these states, and the reliability indicators are calculated based on the history equipment fault records of auxiliary power system. The proposed method is applied to calculate the reliability of the equipments of auxiliary power system of Huizhou LNG power plant.On the basis of reliability model of auxiliary power equipments and system, this paper carries out a study on the reliability and risk assessment of the auxiliary power system of peaking natural power plant based on Monte Carlo risk assessment theory. The multi-level load model of such power plant is built in accordance to the history power generation curve, then the reliability index for each load node of the system are calculated statistically by using the [0,1] uniform distribution, to study the real-time status of all devices and multiple simulations. By applying assumed failures on the basis of these results, the failure probability that may cause the unit outages is calculated and then compared with the multi-level load model of the power plant, therefore the risk index including LOGP (Loss of Generation Probability) and EENG (Expectations of Energy Not Generated) are resolved. The proposed method is applied to perform the operation risk assessment of auxiliary power system of Huizhou LNG power plant.According to the results of reliability calculation and risk assessment, this paper proposes the reliability improvement measures for the auxiliary power system of peaking natural gas power plant. The cost decomposition models of these measures, which contain the cost of equipments’ investment, the cost of equipment operations and maintenances, the cost due to blackout loss and the cost of retirement, etc. are analyzed based on the full LCC theory. Sensitivity analysis theory is introduced to evaluate the sensitivity of the power plant risk to the reliability of the equipments. According to the analysis results, the comparation of these measures are performed based on the LCC theory from both the technical and economic aspects. The proposed method is applied to design the reliability improvement measures of auxiliary power system of Huizhou LNG power plant.