The values of objective functions R and N keep basically equal to the optimization result of MEHS optimal economic benefit before [[alpha].sub.R] reaches 0.7 and equal to the optimization result of MEHS minimum power fluctuation optimization problem when [[alpha].sub.R] is larger than 0.9.
According to Figure 4(b), when [[alpha].sub.R] changes from 0.7 to 0.74 and 0.88 to 0.9, the values of MEHS standard deviations of economic benefit and power fluctuation increase fast; when [[alpha].sub.R] changes between 0.74 and 0.88, the standard deviations basically remained stable.
The WPP and PV generation uncertainties have a great impact on MEHS system operating stably.
Correspondingly, the MEHS economic benefit reduced gradually, but the fluctuation variance of WPP and PV output power reduced correspondingly, which indicates that system needs to bear the corresponding loss of economic benefit in avoiding risks.
Figure 6 is MEHS output power distribution with [[GAMMA].sub.W] = [[GAMMA].sub.PV] = 0.5.
In this section, the optimization effect of the pumped storage power station on MEHS system is mainly analyzed.
According to Figure 7, if pumped storage power stations are not considered in MEHS, the peak-shaving and reserve services of WPP and PV generation are mainly provided by CGT units.
According to Figure 8, if PHSP was considered in MEHS, system peak-shaving and reserve services capacity for WPP and PV power generation increased; WPP and PV power generation also increased correspondingly; abandoned WPP and PV electricity were, respectively, 1 x 7.664 MW x h and 8.358 MW x h.
The MEHS system economic benefits can be improved and the MEHS system operation risk level can be reduced though the process.
According to Figure 9, with the increasing of PHPS grid-connected capacity, MEHS system economic benefits increased correspondingly; the WPP and WPP and PV output fluctuation variance in MEHS reduced gradually, which means that PHSP can provide peak-shaving and reserve service for MEHS system.
Compared with PHSP capacity of 10 MW, the economic benefit of MEHS increased by 7.34% and the risk level reduced by 2.16%.
is about 1:1.3), the economic efficiency and risk level of MEHS reached the inflection point.