售电侧改革、市场主体变化与电价红利:基于讨价还价博弈

本文通过构建“一对多”和“多对多”讨价还价博弈模型,研究了售电侧改革前后,发电商和售电公司之间关于消费者剩余分配的博弈过程。具体来说,文章从售电侧改革带来的博弈主体与博弈机制变化角度,揭示了售电侧改革对用户电价红利的影响。研究发现:售电侧放开后,电力市场交易机制由“一对多”竞价上网变为“多对多”讨价还价匹配,造成了售电侧博弈主体的议价能力下降,发电侧博弈主体相对议价能力上升。发电商群体将索取更多的消费者剩余,从而推动发电侧整体报价的上涨,挤压了售电侧的利润空间,导致售电公司被迫抬高市场电价,最终剥夺了用户的电价红利。研究揭示了售电侧改革未能带来电价下降的根本原因。

Research on the benefit distribution of the electricity retail market after competition being introduced based on bargaining game

The Chinese government started implementing a new round of power system reform since March 15,2015.This reform focused on introducing competition to sectors other than transmission and distribution segments,and allowing electronic distribution business open to the social capital,hoping to reduce the electricity market price through breaking monopoly and introducing competition.However,the previous practice of such reform failed to achieve a satisfying result.Taking the reform in Texas as an example,Joskow and Tirole pointed out that introducing competition may not necessarily make the retail market more efficient,on the contrary,independent companies may still stick to the existed pricing mechanism of previous traditional monopolistic companies,which will not change the situation of high market price.Therefore,it is necessary to put insight into the factors leading to the situation.When analyzing the phenomenon that companies apply the existed monopoly price,most scholars attributed it to the collusion behaviors among monopolistic sales companies.Due to the technical characteristics of the electricity market itself,it is impossible to form a perfectly competitive market.Instead,it is a monopolistic"pseudo-market"where sales companies tacitly cooperate with each other in order to achieve higher returns.However,according to the coalition game theory,the Cartel coalition actually lacks stability,the collusion of monopolistic pricing is not a Nash equilibrium,as there is still motives for members to deviate.In addition,due to the rigorous requirements of collusion monopolies,even if it’s possible,it will only be some individual cases.Even in the markets which first introduce competition,including the United States,the United Kingdom,Russia,and the Nordic countries,such cases are not avoidable.Therefore,the rise of electricity price could only be attributed to a systemic issue brought by the change in trading mechanism which accompanies market competition.Based on the above analysis,this paper investigates the main changes in the gambling subjects as well as the mechanism,to reveal the reason why market competition fails to bring down the price.In the first part,the paper analyses the situation in which power suppliers transmit electric power to the sales companies through bidding online before the reform.In such case,there is only one buyer but multiple sellers in the market,the trading mechanism is a"one to many"game.The second part focuses on the situation after market competition being introduced,where capital is allowed to flow into the electricity business.In this case,there will be more sales companies in the market.In other words,there are multiple sellers and buyers,which forms the"many-to-many"bargaining game.In the third part,we analyze the distribution of consumer surplus between electricity producers and retailers under these two different game mechanisms.In the fourth part,through the numerical simulation,the model analysis result is testified.The last part of the paper provides the conclusions and policy recommendations.The study finds that in the"one-to-many" game,which implies situation before the reform,the final transaction price approaches the minimum reserved price of the generator.Under this trading mechanism,the consumer surplus obtained by the electricity producers approaches zero,and the retailers will receive the total surplus of both parties in the transaction.After the reform,a"many-to-many"bargaining game is formed between the electricity producers and the sellers.Assumed that the initial strategies are random,the evolutionary steady state of the game must be a strict Nash equilibrium,and converges to a symmetric Nash equilibrium(fifty-fifty)with the maximal probability.Meanwhile,the probability of it converging to other strictly Nash equilibriums decreases toward both sides with this as the center.The expected distribution of consumer surplus between generators and electricity retailers is divided into"fifty-fifty".The bargaining power of electricity retailers decreases and that of generators increases accordingly.As a consequence,the generation groups will ask for more consumer surplus to rise their general price,then squeeze the profit margins of the retail side,which forces the sales companies to raise the market price,and ultimately deprive the bonus of consumers.