Application and Design of Technical Support System for

High-Proportion Hydropower Spot Market

Mengfei Xie

, Jianjian Shen

*, Bangcan Wang

, Zebin Jia

, Yang Zhang

, Qihao Zhao

and Na Zhou

Kunming Power Exchange Center Co.,Ltd., Kunming Yunnan 650000, People's Republic of China

Institute of Hydropower and Hydroinformatics, Dalian University of Technology,

Dalian 116024, People's Republic of China

Kunming Power Exchange Center Co.,Ltd., Kunming Yunnan 650000, People's Republic of China

Institute of Hydropower and Hydroinformatics, Dalian University of Technology,

Dalian 116024, People's Republic of China

Institute of Hydropower and Hydroinformatics, Dalian University of Technology,

Dalian 116024, People's Republic of China

Institute of Hydropower and Hydroinformatics, Dalian University of Technology,

Dalian 116024, People's Republic of China

Kunming Power Exchange Center Co.,Ltd., Kunming Yunnan 650000, People's Republic of China

Keywords: Technical Support System, Hydropower System, Spot Market.

Abstract: With the construction of electricity spot market entering the critical stage, the design and development of

feasible and practical spot trading system has become a key task for implementing the application of large-

scale medium and long-term trading plans. This study takes Yunnan high-proportion hydropower spot

market as the engineering background. Considering the system architecture, the overall business function,

and the integration implementation technology, we construct the spot system construction scheme in line

with the hydropower-dominated provinces. Moreover, the integration technology of high proportion

hydropower spot clearing model, the integration technology of large-scale complex optimization solver, and

the whole process business visualization of spot clearing interaction technology are proposed and described.

The developed system realizes the integrated functions of market subject declaration, transaction clearing,

and security check and information release. The rationality, timeliness and practicability of the system are

verified through the simulation applications of Yunnan electricity spot trading.

1 INTRODUCTION

In March 2015, the promulgation of Several

Opinions of the CPC Central Committee and the

State Council on Further Deepening the Power

System Reform marked the beginning of a new

round of power system reform in China With

Document No. 9 as the top-level design, China's

electricity market has achieved rapid development in

the past five years, which can be roughly divided

into two stages: the first stage is the construction of

the medium and long-term market, mainly focusing

on annual and monthly electricity trading. At

present, each province has carried out the design and

practice of medium and long-term trading rules and

trading systems, and the trading scale has been

expanding year by year(Shen, et al., 2022; Liu et al.,

2019); the second stage is the construction of the

spot power market. The first eight pilot projects,

including Guangdong, Inner Mongolia, Zhejiang,

Shanxi, Shandong, Fujian, Sichuan and Gansu, have

prepared spot market rules that adapt to the

characteristics of the province, and developed a spot

technology support system. The simulation

operation has been carried out in 2019. Yunnan,

Jiangsu and other provinces will also start the trial

operation of the spot electricity market(Jia, et al.,

2022;

Andrew et al., 2003).

Looking at the development of the global

power market, due to different power supply

structure, power grid structure, market

characteristics, etc., there are still large differences

between countries and regional electricity

markets(

Rudnick, et al., 2005; Wang et al., 2003;

Zhang et al., 2020). It is difficult for China's power

market to directly apply the theory and technical

198

Xie, M., Shen, J., Wang, B., Jia, Z., Zhang, Y., Zhao, Q. and Zhou, N.

Application and Design of Technical Support System for High- Proportion Hydropower Spot Market.

DOI: 10.5220/0011956700003536

In Proceedings of the 3rd International Symposium on Water, Ecology and Environment (ISWEE 2022), pages 198-206

ISBN: 978-989-758-639-2; ISSN: 2975-9439

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

framework of foreign power markets. For the eight

pilot provinces that have carried out the construction

of electrification markets, market rules and system

characteristics are also different. In addition to

Sichuan, the power supply structure is generally

dominated by thermal power. Taking Guangdong as

an example, the spot market consists of a day-ahead

market and a real-time market, which adopts a

bilateral quotation and a centralized market model.

The pricing mechanism of the power generation side

market is the node price, and the user side is the

weighted average of the node price; in terms of spot

system, as the main power generators in the market

are mainly coal power and gas power units, the

complex nonlinear characteristics of hydropower

units are not considered in the spot clearing model,

and the system functions do not involve such

businesses as matching the clearing results of

upstream and downstream hydropower stations and

hydraulic verification, it is difficult to directly apply

to the high proportion of hydropower spot market.

This paper focuses on the spot market in high

proportion hydropower provinces. Taking Yunnan

as an example, there are more than 180 large

hydropower stations participating in the power

balance, with an installed capacity of about

78200MW, accounting for more than 70% of the

total installed capacity of power generation in the

whole network(Shen et al., 2019). The electricity

market with such a large proportion of hydropower

is greatly different from most domestic and foreign

power markets, which are dominated by thermal

power, gas power. Due to the randomness of runoff,

uneven distribution of time and space, the coupling

characteristics of hydropower and electricity at the

upstream and downstream of the cascade lead to

greater complexity and difficulty in clearing the spot

system, especially in the construction of the spot

technical support system, how to solve a series of

theoretical and technical problems such as dynamic

construction and integration of the hydropower spot

clearing model, efficient solution of large-scale

complex systems and seamless integration of

optimized software, and the realization and

interaction of the integrated business of declaration

clearing verification release, it will directly affect

the smooth completion and real implementation of

Yunnan and other electricity spot markets, and it is

urgent to make theoretical and technological

innovation.

This paper mainly focuses on the technical

level. Focusing on the actual project of Yunnan's

high proportion hydropower spot market, from the

three aspects of the overall system architecture,

overall business functions, and integrated

implementation technology, it constructs a spot

system construction scheme that conforms to the

hydropower dominated provinces, and puts forward

the integration technology of the high proportion

hydropower spot delivery model, the integration

technology of large-scale complex optimization

solver, and the visualized dynamic interaction

technology of the whole process of spot delivery, it

realizes the integration functions of market entity

declaration, transaction clearing, security check,

information release, etc. The timeliness, rationality

and practicability of the system are verified through

the simulation application of Yunnan electric power

spot transaction.

2 THE WHOLE SYSTEM

FRAMEWORK

The power spot market technical support system is

faced with complex business requirements such as

multiple market entities, large amount of data

interaction, and high difficulty in business

integration, especially for the unique operation

business and calculation requirements of the

hydropower system, which requires top-level design

in terms of data storage and service with different

characteristics such as water regime, power,

electricity price, clearing model and algorithm

construction, business functions, based on the

analysis of the actual business needs of spot

electricity trading in the high proportion hydropower

market and the mature enterprise platform

technology, the overall structure of the spot market

technical support system based on tiered services is

constructed. See Figure 1 for details.

Application and Design of Technical Support System for High- Proportion Hydropower Spot Market

199

Figure 1: Overall framework of technical support system for high proportion hydropower spot market.

The overall architecture of the system is

composed of the basic support layer, data storage

and interaction layer, service layer, application layer

and user layer, and all layers cooperate and

authenticate with each other. Among them, the basic

support layer is responsible for the hardware and

software for the stable operation of the entire

system, providing a stable operating environment for

platform construction, and ensuring the high

availability of the system by introducing node,

storage, distributed computing and other load

balancing technologies; the data storage and

interaction layer is responsible for the interaction

and storage of internal and external data in the

system WEBSERVICE, JSON, FTP and other

technologies to achieve seamless real-time

connection with the data centre. At the same time, a

distributed temporal database and a high-

performance memory database for massive

hydrological data storage and high concurrent access

have been built to ensure system stability and

computing efficiency; the service layer is

responsible for all services of the entire spot system,

including data services, algorithm services,

integration services and organization services,

including core services such as hydraulic check

calculation, unit combination optimization and spot

clearing model for high proportion of hydropower

systems. It realizes unified management of all

businesses based on the service bus to ensure loose

coupling between applications; the application layer

relies on various services provided by the service

layer to realize the main business functions of the

spot electricity market according to the business

process, including the medium and long-term

transaction electricity decomposition, market

information management, information management,

market transaction declaration, clearing, and

transaction results display and analysis, among

which the monthly electricity decomposition and

daily curve decomposition mainly consider the

incoming water, water level, and different varieties

of transaction results to achieve the refined

coordination calculation of cascade hydropower

stations, the declaration data verification realizes

the automatic verification of the power generation

boundaries such as the water level, flow and output

of hydropower plants, the hydraulic constraint

verification and spot clearing can simultaneously

consider the nonlinear hydraulic characteristics of

more than 100 hydropower stations and ensure the

accurate matching of the electricity and water

volume of upstream and downstream hydropower

stations through iterative optimization; the user layer

is a visual operation interface presented to market

members and an important entrance for the system

to perform various operations.

3 COMPONENTS OF SPOT

MARKET SYSTEM

Guided by the actual business needs of the high

proportion of hydropower spot market system, the

corresponding medium and long-term and spot

market collaborative business system is designed,

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including market bidding component, application

data integration management and analysis

component.

3.1 Market Bidding Component

This component involves core production businesses

such as the decomposition of medium and long-term

plans and the integration of the whole process of

spot transactions, which can meet the connection

between medium and long-term transactions and the

spot market, as well as the preparation requirements

of the day ahead transaction plan on the power

generation side. The medium and long-term plan

decomposition provides multiple strategies for

decomposing monthly electricity to daily and daily

electricity to curve, covering multiple market

entities such as power generation enterprises and

wholesale users, as well as multiple transaction

varieties such as bilateral negotiation, to ensure an

orderly connection with spot transactions; Different

from the market dominated by thermal power, the

high proportion hydropower spot system needs to

comprehensively consider the predicted inflow

process of the reservoir, as well as complex

boundary conditions such as reservoir water level,

power generation flow, output limit, water balance

equation in Multi-scale trading power

decomposition, so as to achieve high-quality peak

shaving of hydropower and efficient utilization of

hydropower resources while meeting the control

goal of transaction results. The spot market is

carried out in an orderly manner according to the

business processes of market entity declaration,

transaction clearing, security check and information

release, realizing the full business integration

function of spot transactions. For market operation

entities such as trading centres, they can control and

manage the spot market process according to time

nodes in market management, set the declaration

parameters of each market entity in the declaration

module of market entities to flexibly configure the

behaviour of market entities, and integrate the

cascade electricity linkage control spot clearing

method and complex hydraulic constraint check and

adjustment strategy that meet the optimization of

large-scale hydropower stations in the transaction

clearing module, and integrate DC power flow check

AC power flow check and other technologies have

solved the problem of spot clearing efficiency under

the constraint of time-space coupling of water power

and electricity, and avoided the potential power

shortage, water abandonment and other prominent

problems in the result of power generation mismatch

of cascade hydropower stations.

3.2 Application Data Integration and

Analysis Service Component

For high proportion hydropower system, the data

sources for the connection between medium and

long-term spot transactions are extremely complex,

including water level at multiple time scales such as

year, month, day, hour and 15 minutes, inflow flow,

generation flow, waste water flow, two-dimensional

water level storage capacity curve, tail water level

discharge curve, three-dimensional unit HNQ curve

and other complex data different from the main

thermal power market, involving water dispatching

automation system, runoff prediction system, power

trading system ， energy-saving power generation

dispatching system, the interactive data presents

typical heterogeneous and polymorphic

characteristics, and the data processing is very

difficult. Therefore, according to the logical

relationship, category, characteristics and format of

the stored data, a unified data description rule is

established. Based on this, the database mapping

interaction function, chart visualization processing

function, and real-time calculation and check

analysis service function of water regime data

oriented to the transaction clearing process are

realized for different businesses in different time

scales, meeting the dynamic construction of

hydropower station dispatching and grid boundary

constraint processing requirements in actual projects.

This part of functions includes cross application

collection of heterogeneous polymorphic data, basic

data management, operation and indicator data

statistics, and log data monitoring, which can meet

the requirements of medium - and long-term plan

decomposition in actual projects and dynamic

construction of system constraint processing in the

spot clearing model, and provide important data

support for the development of core businesses in

the medium - and long-term and spot markets.

4 KEY TECHNOLOGIES

4.1 Integration Technology of High

Proportion Hydropower Spot

Clearing Model

As the core business of the clearing link of spot

electricity trading, the spot clearing model needs to

Application and Design of Technical Support System for High- Proportion Hydropower Spot Market

201

consider the automatic construction technology of

large-scale power plants and their complex

constraints and the model adaptive technology to

adapt to different trading rules and needs, especially

for the high proportion of hydropower spot market,

the differences in the geographical location,

regulation performance, installed capacity, incoming

water size, water level status, unit characteristics of

the cascade hydropower stations, it will have a great

impact on model construction and adaptability. To

this end, the integration technology of high

proportion hydropower spot clearing model is

proposed to solve the problem of hydropower spot

market clearing model integration from two aspects:

the automatic description and integration of model

boundary conditions, especially the characteristics of

hydropower system, and the target and constraint

configurable component integration library. See the

following for the detailed integration technology。

1）Automatic description and fusion of hydropower

system characteristics

The main difference between hydropower system

and thermal power system is that they involve many

complex nonlinear hydraulic characteristics and are

uncertain. There are also large differences between

river basins and upstream and downstream power

stations. Especially for the high proportion of

hydropower market, spot clearing modelling is

required to realize the automatic description and

integration of these characteristics. Therefore, a

directed graph description technology for the

relative spatial position of cascade hydropower

stations is proposed. By constructing the directed

graph cascade topology structure, the topology and

time sequence relationship between hydropower

stations can be automatically analysed to adapt to

the differences and changes in the composition

structure of hydropower stations in different basins;

The hydraulic condition analysis and fusion

technology based on the automatic transaction

mechanism is proposed, which defines the

characteristics, frequency, mode and other

transaction rules of incoming water, output, water

level, flow and other data, and combined with

JAVA multithreading technology, the automatic

timing processing of different scales and different

data businesses is realized, and the data encoding

and matching technology is used to automatically

integrate contract type data, which significantly

improves the analysis accuracy of complex

hydraulic data; The automatic modelling technology

for the restricted area of complex units of SCUC and

SCED high head large capacity units is proposed.

The irregular multi restricted operation area

constraints of southwest giant hydropower units can

be automatically incorporated into the spot clearing

model by using polygonal subdivision linearization

approximation modelling, so as to avoid

unreasonable transaction results

2）Hydroelectric target and constraint configurable

component integration library

The dynamic changes of spot market clearing rules,

dispatching conditions of hydropower system and

operation demand put forward new requirements for

the construction of clearing model, and it is

necessary to build an extensible component

integration library to cope with the flexible changes

of clearing rules. The clearing model is divided into

two parts: objective function and constraint

condition, and a flexible configuration component

library are constructed respectively. Each

component library can be freely combined to form

an extensible integration library. The objective

function library is composed of various objective

functions facing different business needs, including

the optimal cost category, the largest clean energy

consumption category, such as the largest

hydropower consumption, the smallest risk category,

such as the minimum risk of abandoned water, the

minimum risk of power shortage, the constraint

library involves different classification standards,

including classification by power type, classification

by constraint characteristics, etc.

4.2 Integrated Technology of Large-

Scale Complex Optimization

Algorithm

The solution of the clearing model in the spot

electricity market itself is a complex optimization

problem, especially in the high proportion

hydropower system, which is recognized as one of

the most complex systems in the world. Due to the

nonlinearity of hydropower itself and the coupling

constraints between the cascades, the clearing

problem has the characteristics of non-convex,

nonlinear, discrete, high-dimensional, and is facing

outstanding difficulties in solving. The traditional

solution methods include dynamic programming

methods, intelligent optimization algorithms, etc.

However, as the scale of the problem increases, the

control conditions and constraints of the model

increase significantly, and the traditional dynamic

programming methods have serious "dimension

disaster" problem; Although intelligent optimization

algorithms such as genetic algorithm and simulated

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annealing algorithm can flexibly deal with various

nonlinear constraints, and there is no dimension

disaster problem, the algorithm is essentially a

random optimization, which cannot guarantee the

global optimal solution, and has insufficient

stability, which is not conducive to the traceability

of results; The mathematical planning method model

is flexible in construction, which can ensure the

stability of the solution. It is currently a common

method to solve the problem of large-scale spot

clearing.

In order to ensure the efficient solution of large-

scale complex clearing model of high proportion

hydropower system and improve the automation of

clearing modelling and solution of spot system, a

large-scale complex optimization solver integration

technology is proposed by integrating multiple

optimization solvers into the spot system. The core

idea of this technology is based on the standard

interface program provided by the optimization

solver, using Java API modelling standardization

tool software, to automatically realize the docking

with the solver, specifically through the following

steps: first, load the specified optimization solution

interface call package to the specified project path,

and build the solution environment; second, analyse

the format specification of the designated algorithm,

and use Java programming language to express the

cash clearing mathematical model as the

optimization model that the solver can recognize

according to the format specification requirements;

third, call the optimization solver solution engine to

solve the model, and use the query function to view

the model solution results. The integrated

technology of complex optimization algorithm is

adopted to integrate many different optimization

algorithms into the spot system, which can

effectively realize the automatic construction and

solution of the clearing model, and greatly improve

the automatic clearing modelling capability and

efficiency of the spot system.

5 APPLICATION

5.1 Practical Engineering

Yunnan Power Grid is a typical high-proportion

renewable energy grid dominated by hydropower. It

is the main delivery end of China's West East Power

Transmission Project. In the face of large-scale clean

energy export, hydropower is subject to the impact

of uncertain runoff in the process of consumption

and spot trading, and the close hydropower linkage

between the terrace hydropower plants. At the same

time, grid security constraints limit the flexibility of

bidding, increasing the difficulty of market clearing;

In addition, core businesses such as medium and

long-term connection with spot transactions involve

heterogeneous and polymorphic data collection,

storage, query, processing and analysis, which bring

great challenges to the development of the spot

market.

Based on the platform architecture and key

technologies of a high proportion of hydropower

spot market, the core business of medium and long-

term plan decomposition and spot trading is realized.

Taking the actual project in Yunnan as an example,

the whole process of core business in the spot

market has been realized by using this platform.

5.2 Application Analysis of Technical

Support in Spot Market

The functions of the spot market involve the

declaration of market entities, the clearing of

transactions, the security check and the release of

results. Among them, the spot market clearing

model is the core of the optimal allocation of

resources. It needs to combine the volume and price

information declared by market entities, grid

boundary constraints and security constraints,

hydropower and power connection of cascade

hydropower stations, and at the same time consider

the information such as the runoff forecast of

hydropower stations to achieve the optimization goal

of maximizing the social welfare of the whole

network, that is, minimizing the power purchase cost.

In the day ahead spot verification, the spot

market system integration technology was used to

carry out the core business of market entity

declaration, day ahead clearing, verification and

result release. As shown in Figure 2, market entities

can declare the time and electricity price curve of

the next day; after the declaration of each market

entity is completed, carry out the day ahead clearing

and verification, as shown in Figure 3. Under the

hydraulic constraints of cascade hydropower stations

and the grid security constraints, the day ahead

clearing results meet the requirements of the whole

network load balance, and the system takes about 5

minutes to solve, meeting the timeliness

requirements; as shown in Figure 4, the statistics of

multiple clearing results, such as units, nodes and

cross section channels, are also provided to facilitate

the trading centre to query the clearing results.

Application and Design of Technical Support System for High- Proportion Hydropower Spot Market

203

In the case study, two cases are presented. The

first case focuses on influence of navigation

constraints on cascaded hydropower system

operations. The last case concerns the influence

degree of annual inflow on operation results under

navigation constraints.

Figure 2: Typical interface of market subject declaration.

Figure 3: Typical interface of day-ahead market clearing.

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Figure 4: Typical interface of market clearing results.

6 CONCLUSION

The reform of China's power market has entered a

deep-water area. As the energy base of "Power

Transmission from West to East", some high-

proportion hydropower provinces in southwest

China, such as Yunnan, Sichuan, Guizhou, Guangxi,

Chongqing and Tibet, have important characteristics

and representativeness in their spot market

construction. However, they also face many

theoretical and technical challenges that have not

been encountered in the spot market dominated by

thermal power. It is of great practical significance to

build a spot trading technical support system suitable

for these high-proportion hydropower markets.

Combined with the construction and practice of

Yunnan's spot electricity verification system, this

study gives the overall technical architecture and

main components of the system in detail,

systematically expounds the hydropower spot

clearing model and integration technology,

optimization algorithm integration technology.

Finally, the simulation verification of the spot

electricity clearing through the 96-point actual

operation data of Yunnan Power Grid for many days

is carried out. The results show that the constructed

technical support system can converge in a short

time, and obtain the day-ahead clearing operation

schedules.

ACKNOWLEDGEMENTS

The authors acknowledge the National Natural

Science Foundation of China (52079014) and the

Fundamental Research Funds for the Central

Universities (Nos.DUT22QN224 and DUT22JC21).

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