关键词: 可再生能源发电商, 售电商, 绿色证书, 超额消纳量, 激励机制

Abstract: Encouraging electricity sellers to actively fulfill the Renewable Portfolio Standards (RPS) obligation will be the meeting point of balancing the relationship between the quotas system and the electricity market reform. China fully launched the monitoring and assessment mechanism of RPS in 2020, which is one of the most common and successful policies to reduce carbon emissions and promote the utilization of renewable energy technologies. In fact, the “Notice on the Establishment and Improvement of the Renewable Energy Power Consumption Guarantee Mechanism” (i.e., RPS) stipulates that the power grid, electricity selling enterprises and other electric power entities shall assume the responsibility of renewable energy consumption. Hence, according to the policy, in order to achieve the quotas target, power sellers can purchase green certificates or excess consumption of renewable energy from renewable energy generators to fulfill the corresponding quotas obligation. Based on this fact, this paper constructs the decision model of quotas trading cooperation between renewable energy generators and upstream and downstream enterprises of electricity suppliers, deconstructs the external incentive model under the single cooperation path and the double incentive model under the continuous cooperation path. This paper aims to quantitatively study the incentive effect of bilateral transactions from the perspective of power sellers, which has strong theoretical significance and application value for increasing the scale of investment in renewable energy, activating renewable energy market transactions, and deepening the reform of electricity market.
Regarding the incentive mechanism of green certificate trading between renewable energy generators and electricity sellers, this paper mainly considers two different trading cooperation situations, firstly, namely single cooperation path and continuous cooperation path, since the incentive effect is different under different cooperation paths. The single cooperation path is that renewable energy generators consider a single cooperation, and electricity suppliers also consider a single cooperation. And continuous cooperation path is that renewable energy generators and electricity suppliers are considering continuous cooperation. Therefore, the decision-making process of green certificates quotas trading considers the external incentive policy of quotas power sale subsidy under the single cooperation path. And the internal incentive mechanism of cooperation interest coordination is considered based on the subsidy policy of quotas power sale under the path of continuous cooperation, that is, internal and external double incentive mechanism respectively. Because renewable energy power and green certificates can be bundled or separated, the green quotas trading can be also divided into two modes. Hence, the incentive based optimal decision model is analyzed under the two quotas trading modes, i.e., the bundled transaction mode of electronic certificates and the pattern of separation of electronic certificates respectively. Finally, the paper focuses on the change in maximum cooperation revenue of both parties and the influence of incentive parameters on market electricity price and green certificate price, aiming to fundamentally alleviate the contradiction that the RPS system is difficult to adapt to the electricity market reform.
The main results indicate that external subsidies promote the increase in single cooperation income. The bundled trading pattern of power and certificates is an important way for power sellers to achieve the quotas target, and corresponds to an optimal subsidy amount. If government fortifies the subsidy for power quotas sale, the trading pattern of separation of power and certificates can produce a prominent incentive effect. Under the continuous cooperation path, the condition for renewable energy power generators to obtain the maximum benefits is equipped with higher sharing proportion of benefits and medium proportion of quotas cost. However, reducing the cost sharing ratio will still lead to an increase in the price of green certificates. No matter what kind of quotas trading pattern, the internal cooperative interest coordination mechanism can restrain the market electricity price and green certificate price rise.
The research is expected to provide a theoretical basis for Chinese government decision-makers to design an incentive scheme that is compatible with the reform direction of the RPS system and the electricity sales side, find a quotas trading model that can improve the consumption of renewable energy market, and at the same time, and relieve the contradiction between reducing the quotas cost and increasing the economic benefit of electricity sales entities.

Key words: renewable energy power generators, power sellers, green certificates, excess consumption of renewable energy, incentive mechanism