طرح قیمت گذاری انتقالی مبتنی بر تعرفه نقطه به نقطه و تطبیق کردن جفت معامله برای بازار استخر

Transmission pricing scheme is a key component in the infrastructure of power market, and pool is an indispensable pattern of market organization; meanwhile, pay-as-bid (PAB) serves as a main option to determine market prices in pool. In this paper, a novel transmission pricing scheme is proposed for pool power market based on PAB. The new scheme is developed by utilizing point-to-point (PTP) tariff and introducing an approach of transaction pair matching (TPM). The model and procedure of the new scheme are presented in detail. Apart from the advantages of existing transmission pricing schemes, such as ensuing open, fair and non-discriminatory access, proper recovery for investment as well as transparency, the new scheme provides economic signals to promote the maximum use of the existing transmission network, encourages appropriate bidding behaviors in pool, and helps to reduce the possibility of the enforcement of market power and the appearing of price spikes; thus improves market operation efficiency and trading effects. In order to testify the effectiveness of the proposed scheme, a case based on IEEE 30-bus system is studied.

One of the most outstanding issues in the liberalization of power market is transmission pricing, which has significant impacts on the market efficiency. Transmission pricing scheme is a key component in the infrastructure of power market, ensuring open, fair and non-discriminatory access [1], [2], [3] and [4]. It is a challenging task to allocate the overall cost of transmission network among all users equally while provide them with correct, market-based economical signals at the same time [5]. In general, transmission pricing schemes appearing in the current literature could be classified into two basic philosophies: point-of-connection tariff scheme (POC) and point-to-point tariff scheme (PTP) [6] and [7]. The basic principle of POC is that market participants pay specific transmission fee according to the points they connect to in the network. The main advantage associated with POC is its simplicity. Transmission prices for each point are always pancaking of the local transmission costs on the principle of postage-stamp, which are public to all involved parties, including customers, generation corporations, load service entities and so on. POC is widely applied, as it could be either suitable for bilateral trading or pool competition. However, there are also distinct drawbacks of POC. On the condition of ignoring the actual status of system operation, POC tariff is not figured out according to the actual usage of the network, which means charges are independent of the distance and connection between the power source and the drain throughout. Hence, ineffective transactions would be approved while the payments for power delivery at POC tariff could not cover the transmission cost incurred by the transaction, which occupy plenty of transmission capacity and cause great transmission losses. Therefore, economical signals that generated by transmission pricing is distorted, resulting in reduction on market efficiency and trading effects [8]. Contrarily, the basic principle of PTP is that market participants pay transmission fee according to particular transaction pairs from named sellers to named buyers. PTP tariff is determined according to the augments of power flow in transmission facilities of the network caused by the transaction. By introducing PTP tariff in power trading, effective economical signals are generated and sent; participants will consider the distinctions of tariff for different transactions when making their decisions. Obviously, transactions with lower PTP tariff will be preferred, thus the maximum use of the existing system could be promoted [5] and [6]. In order to assess the actual usage of transmission network incurred by specific transactions, various effective methods have been proposed, such as MW-Mile, monetary path, contract path, counter-flow methods and so on [9], [10], [11], [12], [13], [14], [15] and [16]. However, PTP is not applied in pool market, as in which generation schedules are always determined unilaterally. Therefore, no transaction pairs like bilateral contracts are matched, and it's not necessary to clarify PTP tariff [17]. Pool is an indispensable pattern to power market, especially in short-term trading and real-time balancing mechanisms; while pay-as-bid (PAB) serves as a main option to determine market prices in pool competition [18] and [19]. As pool market is always organized oligopolistic-based, with inelastic demand, it is easy for participants to enforce market power, leading to price spikes and uplift in purchasing cost [9]. As transmission fee always accounts for a big proportion of transaction cost in power trading, it is taken into consideration when market participants are making decisions on trading strategies. In this case, transmission tariff could serve as a “tool” for the function of market regulation by sending correct economic signals to users of the network, promoting reasonable behaviors, effective competition and stable operation of the market [20] and [21]. However, since POC is always adopted in pool market, the function of market regulation is unavailable as economic signals disappear in the uniform POC tariff. In this paper, a new transmission pricing scheme based on PTP tariff is proposed for pool market based on PAB. The new scheme is carried out along with the organization of pool market, while not interfere with the process of pool in order to keep its transparency. Bilateral transaction pairs are matched in sequence on the principle of achieving maximum utility incurred by the transaction pair, with utility representing buying price minus selling price and corresponding PTP tariff. In this case, the function of market regulation is developed as economic stimulation could be offered by the differences in rates of PTP tariff. In order to testify the effectiveness of the new scheme, a case of pool market based on IEEE 30-bus system is studied. For the sake of simplicity, the scheme proposed in this paper is denoted as TPM (transaction pair matching) scheme for short. The paper is organized as follows: firstly, an introduction to pool market in China's power sector is depicted in Section 2; secondly, TPM scheme is described and formulated in Section 3; then, case study is done in Section 4; and finally, Section 5 provides the conclusion.

The research in this paper focuses on a novel transmission pricing scheme, TPM scheme, which combines PTP tariff into pool market based on PAB by means of transaction pair matching. PTP tariff is determined to reflect the actual usage of transmission network, sending correct economic signals to market participants. TPM scheme serves as a simple “plug-in” component for pool market, which is carried out along with the organization of pool and will not interfere with its process. A numerical case of IEEE 30-bus system is studied. The results of the study shows that by utilizing TPM scheme, appropriate punishments and rewards would be imposed on market participants according to their bidding prices. Reasonable bidding behaviors will be encouraged by being given better chances of choosing trading objects in order to pay less transmission fee. Hence, transmission price is taken as an effective way in market regulation by offering economic stimulations. Therefore, gambling behaviors in pool market could be effectively restrained, risk of price spikes could be reduced, and the enforcement of market power would be mitigated. However, the work in this paper is a completely new explore in transmission pricing scheme. Lots of more efforts should be made to improve the designation of TPM scheme before TPM could be applied in real market operation, especially taken into consideration various patterns of network model, the appearing of transmission congestions as well as more complicated bidding strategies. Hopefully, this paper could provide a new idea in the research area of transmission pricing scheme.