Short-term reliability evaluation for power stations by using Lz-transform

Abstract

A short-term reliability evaluation is used for power stations, where each power generating unit is presented by a multi-state Markov model. The main obstacle for reliability evaluation in such a case is a ''curse of dimensionality''-a great (huge) number of states of entire power station that should be analyzed. A modern approach is proposed based on using Lz-transform that drastically simplifies computation. The proposed approach is useful for power system security analysis and short-term operating decisions. In order to illustrate the proposed approach, the short-term reliability evaluation for a power station with different coal fired generating units is presented.

Short-Term Reliability Assessment of Generating Systems Considering Demand Response Reliability

“…Step 6: Calculate the reliability indices of generating systems at moment t k , L OLP (t k ) and E UL (t k ), according to (34) and (35), respectively.…”

“…Firstly, multi-state Markov models apply to the reliability modelling of equipment such as coal fired power generators [34], [35], rapid start-up generators and wind farms [36], and thermostatically-controlled-loads [37]. Furthermore, UGFs and Lz-transforms [35]- [38] are appropriate for dealing with complex multi-state systems: the Lz-transform method is applied to short-term reliability evaluation of power stations in [35], decreasing drastically a computation burden; UGFs are used to establish the time-varying reliability models of wind farms, conventional generators and rapid start-up generators in [36]; the multi-state reliability model of operating reserve provided by thermostaticallycontrolled-loads is represented by the Lz-transform approach in [37]; and in [38], UGFs are used to represent the capacity distribution of generators and the demand distribution of nodes. Despite those recent findings about the mechanism of short-term reliability, there is a lack of short-term reliability modelling of DR, which includes the state division of DR response capacity and the estimation of transient distribution, making it difficult to evaluate the operating risk of generating systems during the period of DR events.…”

Multi-state operating reserve model of aggregate thermostatically-controlled-loads for power system short-term reliability evaluation

“…(21)- (26) is illustrated in Fig. 4(a LZ-transform, which is an extension of traditional universal generating function (UGF) technique [17], [18], has been proved to effectively represent multi-state units for discrete-state continuous-time reliability evaluation [20], [21]. Hence, LZ-transform is applied in this paper to represent the power output distribution of MORTi (t) and can be defined as the following polynomial:…”

“…The effectiveness of UGF in power system longterm reliability evaluation has been verified in [19]. As an extension of conventional UGF, Lz-transform approach is put forward to involve in the time-varying probabilities of different states so that the dynamic reliability of the multi-state system can be evaluated [20], [21]. This allows the Lz-transform approach to be applied to power system short-term reliability evaluation considering hybrid generation and reserve providers [10].…”

Reliability of nonrepairable phased-mission systems with common bus performance sharing

“…where U h and Y h can be obtained from equations (6) and 7, separately. At the end of phase h 14h4H ð Þ , the system succeeds if the amount of performance deficiency after performance sharing is exactly equal to zero.…”