基于灰色马尔科夫预测的PPP项目特许期调整模型研究*

Research on Adjustment Model of PPP Project Concession Period Based on Grey Markov Forecast

摘要:

特许期的是决定PPP项目(Public-Private-Partnership,公私合营项目)成败的关键因素,而现今其投入运营后的调整措施尚缺乏。为此,本文针对已投入运营的污水处理PPP项目,构建了基于对未来现金流分析的特许期长度调整模型。为确定项目未来现金流中关键因素污水处理量的取值,采用灰色预测模型对其进行预测,并使用经过修改更符合本文模型要求的马尔科夫模型对预测结果进行修正,进而与净现值特许期决策模型结合,计算得出建议调整的特许期长度。基于对某污水处理厂的实证研究表明：当污水处理PPP项目的实际污水处理量出现明显偏差时,本文建立的特许期调整模型能够克服概率统计依据历史经验而产生的不足,结合运营后的实际数据,计算后建议在实际污水处理量明显偏高时将特许期缩短7年,发生锐减而明显偏低时延长5年,更符合实际情况。本文旨在为投入运营的污水处理PPP项目的特许期调整提供依据。

Abstract:

In this paper, a concession period adjustment model based on the analysis of future cash flow is constructed for a kind of PPP (Public-Private-Partnership project), WWTPs (wastewater treatment plant), that have been put into operation. In order to determine the value of the wastewater treatment capacity which is one of the key factors in the project future cash flow, using the grey forecasting model to predict it, and using the Markov model to amend the forecasting result, and then with the net present value concession decision model, calculated and proposed adjustment to the length of the concessionaire. Based on the empirical study of a WWTP, it shows that when the actual wastewater treatment capacity of the WWTP is obviously higher or lower than the expected value, the model of the adjustment period established in this paper can be combined with the actual data after operation and obtain a shorter and a longer concession period respectively, more in line with the actual situation. The purpose of this paper is to provide a basis for the adjustment of the concession period of WWTPs put into operation.