| The Tradable Green Certificates(TGC)is an important institutional guarantee for achieving the goals of carbon peak and carbon neutrality.On the one hand,the Tradable Green Certificates system takes the Tradable Green Certificate(TGC)market as the carrier to internalize the positive environmental externalities of renewable electricity.On the other hand,the Tradable Green Certificates system realizes the sharing and optimized allocation of energy elements nationwide.China’s Tradable Green Certificates system was officially launched on 1 July 2017,and a series of policy documents were issued by the government to support it.With the increase of people’s willingness to consume renewable electricity,the liquidity of the Tradable Green Certificates market has gradually increased,and the behaviors of the trading subjects have become more complex.In the Tradable Green Certificates market,the market subjects with limited rationality would like to try to establish contact with other subjects and imitate trading strategies to enhance their own effectiveness.The imitation behaviors among market individuals spread in the group,which is manifested as herding behavior.Furthermore,the mutualistic symbiosis relationship formed by imitation behaviors drives the co-evolution of herding behavior.However,the irrational strategies of some market subjects will gradually spread under the effect of the co-evolution of herding behavior,which will disturb the stable operation of TGC market and increase the investment risk of renewable energy,leading to affect the performance of the TGC.Based on these,this thesis studied the co-evolution of herding behavior in the Tradable Green Certificates market.At present,the research on the TGC system focus on individual behavior,and domestic and foreign scholars have not conducted in-depth research on market subjects’herding behavior,which leads to ignore the complex phenomena emerging from herding behavior from a macro perspective.Therefore,this thesis made a beneficial exploration from the theoretical and methodological level to grasp the co-evolution law of herding behavior in the TGC market,and provided theoretical and practical reference for improving the stability and institutional performance of the TGC market.The main research work and achievements of this thesis were as follows:(1)The emergence phenomenon of herding behavior in the TGC market has been studied.In order to clarify the emerging conditions and process of herding behavior,first of all,based on emergence theory and questionnaire Method,this thesis analyzed the emergence mechanism of herding behavior in the TGC market from three stages of individual behavior generation,group behavior generation and herding behavior emergence.Then,this thesis constructed a herding behavior emergence model of the TGC market with multi-level nested relations based on the mental model,constrained generating procedure model and system dynamics model.Finally,this thesis analyzed the law of herding behavior emergence through computational experiment,and put forward policy recommendations accordingly.The results show that:①The herding behavior exists in China’s the TGC market,and the positive feedback relationship among adaptive subjects will encourage small and medium-sized vendors to establish interactive relationships around large vendors,and cluster through mutual imitation under the convergence effect,and then emerge high-level herding behavior.② The fundamentals strategy,the momentum strategy,and the reverse strategy of the subjects will emerge out of the herding behavior.Among them,The emergence of herding behavior of the fundamental strategy subject with high quality information has scale effect and structure effect,which will emerge out of the herding behavior only when the initial imitation size of 40%or less than 50%,and the emergence depth increases in the shape of "S".However,the emergence depth of other subjects’ herding behavior is not affected by heterogeneous information and belief.The emergence speed is positively correlated with the initial imitation scale,and negatively correlated with the market share.③The weakening of herding psychology and cognitive bias of the trading subjects will reduce the emergence speed of herding behavior,but has no significant effect on the emergence depth.(2)The co-evolution mechanism of herding behavior in the TGC market has been studied.In order to explore the co-evolution process of herding behavior in the TGC market and provide a basis for the optimization strategy of market subjects first of all,this thesis analyzed the co-evolution mechanism of herding behavior from the two dimensions of network and strategy,and revealed the "spatial reciprocity" mechanism of co-evolution of herding behavior.Then,based on the complex network theory and evolutionary game theory,a co-evolution model of herding behavior in the TGC market was constructed,and an improved Fermi learning mechanism was proposed for the random game learning process based on the comprehensive empowerment of neighbor benefits during the memory period.Finally,this thesis explained the co-evolution path of herding behavior through computational experiments,and put forward relevant policy suggestions.The results are as follows:①The co-evolution of herding behavior is a process in which the green certificate traders continuously update the network structure and strategy to the equilibrium state based on the mutualistic symbiosis relationship,which promotes the diffusion of reverse strategies and improves the fairness of the subject’s interest distribution.②The heterogeneity and aggregation of the social network of transaction subjects are gradually significant,making some large manufacturers become the "central node",and form a feedback reciprocity relationship with other manufacturers.③The lack of communication channels between large manufacturers and small and medium-sized manufacturers in the market can alleviate the information blockage between the two types of players by moderately improving the network connectivity;④ The high expectation of market public opinion on the price of green certificates will accelerate the co-evolution of herding behavior,and on the contrary,it will reduce the evolution speed.⑤The improvement of the learning rate,the willingness to imitate and the shortening of the memory period will accelerate the evolution of herding behavior,but also reduce the stability of the equilibrium strategy.(3)The impact of co-evolution of herding behavior on the stability of the TGC market has been explored.The herding behavior may cause excessive price fluctuations of green certificates,which is not conducive to the stable operation of the market.This thesis analyzed the effect of herding behavior on the stability of the TGC market and designed the TGC market stability mechanism accordingly.First of all,this thesis analyzed the influence mechanism of herding behavior on market stability based on behavioral finance theory.Then,based on the multi-subject model and the complex network model,a computational experimental model for the influence of co-evolution of herding behavior on the stability of the TGC market was constructed,and an evaluation method for the stability of the TGC market was proposed.Finally,the effects of co-evolution of herding behavior of homogeneous and heterogeneous strategies on market stability were analyzed by computational experimental methods and empirical test methods,and the implementation effects of price stability mechanism,quantity stability mechanism and price-quantity stability mechanism were further discussed.The results show that:①There are multiple feedback paths between the co-evolution of herding behavior and market stability.Among them,the fundamental strategy promotes the convergence of certificate price to value and improves market stability,while the momentum strategy and the reverse strategy expand the amplitude and frequency of price fluctuations and reduce market stability,respectively.② The co-evolution of herding behavior can intensify the short-term momentum effect and long-term reversal effect of the market,and the herding effect of quota subjects is stronger than that of green power manufacturers.③ The price-volume stabilization mechanism proposed in this thesis weakens the short-term momentum effect and long-term reversal effect of the market,and improves the market stability.④The price stability mechanism weakens the short-term momentum effect,but it is difficult to find the potential supply and demand imbalance risk of the market,while the quantity stability mechanism weakens the long-term reversal effect,but makes the short-term momentum effect of the market enhanced.(4)The impact of herding behavior on the performance of the TGC system has been explored.The herding behavior of trading subjects can affect the stable operation of the TGC market,which further affect the innovation and investment of renewable energy technology.In order to improve the system performance,this thesis explored the effect of herding behavior on the performance of the TGC system,and discussed the reasonable institutional arrangement accordingly.First of all,this thesis explained the influence mechanism of the co-evolution of herding behavior on the performance of the TGC system,and proposed a multi-level interaction relationship of "behavior-system performance-institutional arrangement".Then,the multi-agent model,learning curve and multiple regression model are comprehensively used to construct a computational experimental model on the impact of co-evolution of herding behavior on the performance of the TGC system.Finally,the effect of co-evolution of herding behavior on institutional performance has been analyzed through computational experiments,and the implementation effect of institutional parameter optimization scheme has been discussed.The results show that:① The co-evolution of herding behavior stimulated the innovation and investment of renewable energy technology and improved the dynamic efficiency of the system,but to some extent,it distorted the price of green certificates and increased the investment risk of renewable energy.② The increase of quota proportion will enhance the path dependence of the co-evolution of herding behavior,which will make institutional performance improved,but increase the compliance cost of quota subjects.③Compared with the fixed penalty mechanism,the dynamic penalty mechanism proposed in this thesis increases the diffusion depth of the fundamental strategy by 23%,and accelerates the incentive of the system.④The limited storage validity period reduces compliance costs and promotes renewable energy investment,and the validity period of 6 months is more appropriate.⑤Although the introduction of the lending mechanism reduces the compliance cost,it will also restrict the investment in renewable energy,and the government should carefully consider the introduction of the lending mechanism. |
