2012 4th International Conference on Signal Processing Systems (ICSPS 2012)
IPCSIT vol. 58 (2012) © (2012) IACSIT Press, Singapore
DOI: 10.7763/IPCSIT.2012.V58.31
Ecological Scheduling Decision Support System Based on RIA and
Cloud Computing on the YaLong River Cascade Project
Xu Gang 1 , Li Shao-Cai 2 and Sun Hai-Long 2
1
+
College of Hydraulic and Environmental Engineering, China Three Gorges University, YiChang, China
2
College of Life Science, Sichuan University, ChengDu, China
Abstract. With the case of decision support system for ecological scheduling on the YaLong river
cascade project, the principle of ecological scheduling decision was analyzed. The computing method of
ecological flow was studied and the ecological scheduling model was built. This paper present the
decision making technique. The system solution and key techniques were discussed. An integrated
system for ecological scheduling decision-support system was designed under the environment of RIA.
Based on the cloud computing, a scalable architecture for distributed system was built.
Keywords: RIA; cloud computing; decision support system ecological operation schedule;
1. Introduction
China is a country where water conservancy and hydropower construction are important. Since the 1990s,
ecological problems near rivers have become increasingly serious, and Chinese water conservancy and
hydropower construction has transitioned from a phase of capital, technology and other constraints into a
phase dominated by ecological constraints. Therefore, how to effectively reconcile the contradiction between
river development and environmental protection has presently become the most urgent issue related to the
construction of water conservancy and hydropower projects. In order to provide hydroelectric power station
cascade optimal decision support, some organizations in China had developed a number of decision support
software which ware based on C/S(Client/Server) mode and had been played a huge economic benefits[1].
With the phase of water operation and management into the ecological constraints and the rapid development
of Internet technology, these systems can not meet the needs of the enterprise and users. There are major
problems: 1)the shortage of decision target from the perspective of ecological, 2)unclearly definition of
system decision-making process, a lack of abundant functions for decision support, 3)a lack of the ability to
meet the business on the Internet to interact in real-time computing , 4)facing the situation of scale river basin
development and complex ecological demand constrains ,the system is not agile enough to expansion and
upgrade smoothly,5)the existing system is restricted to the local impact of a single power station. The
guideline for the sustainable development and utilization of water resources in the whole process of
hydropower cascade development are urgent scarce. For the sake of common issues in similar domestic
systems,this study proposed hydropower ecological scheduling decision support system in Yalong River for
ecological principles of ecological regulation and operation of decision- making. Then this study discussed
ecological scheduling decision support system integration Solution and key technologies.
2. System Development Background and Requirement Analysis
+
Corresponding author.
E-mail address: xugang@ctgu.edu.cn
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The Yalong River is located near the upper reaches of the Yangtze River, the largest tributary of the
Jinsha River. The total length of the Yalong River is 1571 km, and includes a watershed area is 136000 km2.
There is a distance of 1368 km and a natural elevation drop of 3180 m separating the Xayi Temple, on one of
the branches of the Yalong River, and the Jiangkou Channel. There are 412 km between the Kara and the
Jiangkou Channels, with a natural drop is 930 m between the two. Within the described area, the total
exploitable capacity in technology is 14.7 million kW. Five hydropower plants have been constructed or are
under construction: Jinping I (3.6 million kW); Jinping II (4.8 million kW); Guandi (2.4 million kW); Ertan
(3.3 million kW); and Tongzilin (600,000 kW). Jinping I is a controlled reservoir of this reach, with annual
regulation ability that provides remarkable benefits to the compensating regulation of cascades in the
downstream. Jinping II power station is a diversion-type hydropower station with a long tunnel, created by
constructing a water-retaining dam at Maomao Beach, which is located in the western section of the Jinping
Big Bend in the Yalong River. The dam generates power for the Da shuigou factory of the eastern section of
the Jinping Big Bend through a straight channel, to create a 119-km-long water-reduced reach between the
Maomao Beach lock site and the Da shuigou factory site. As the volume of water in the river is reduced, the
interval flow and the water depth will decrease, the velocity will slow, and the water temperature and
hydrological situation will suddenly change. If we do not consider periodic discharge of water for ecological
reasons after the power plant is built, especially in the dry season, water flow will cease in most of the rivers,
which will cause death of aquatic organisms due to the loss of aquatic habitat. These changes will have an
extremely negative impact to the river ecological environment. According to the seasonally varying aquatic
life cycles, a prescribed amount of water, the process volume of ecological water requirements, should be
discharged periodically to ensure that the water-reduced reach still supports aquatic habitat functioning and
reduces the eco-environmental stress of the river channels.
Facing the new requirements in ecological scheduling of enterprise information construction at
hydropower development base witch represented by the Yalong River Hydropower development in the west
china, Supported by ministry of environmental protection of special commonweal research projects, Sichuan
University and China Three Gorges University developed ecological scheduling decision support system. The
system user interface was based on RIA technology platform. All the applications of the system ware web
services, namely, SaaS, Software as a service. The software fully functional, interactive, easy to use which has
not only ecological operation of computing and decision support capabilities, also has information
management, query, print and other functions. The software can meet the ecological health of the watershed
based on cascade of ecological planning and ecological operation scheduling needs of decision-making.
3. Optimal Scheduling Principles and Decision-Making for Hydropower
Stations
3.1. Principles of ecological scheduling
1) Ecological principles to meet the river ecological requirements
Along with hydropower development and operations there was inevitably impact on the ecological health.
According to the criteria of near-natural recovery[2], the hydropower stations could lessen the ecological
environmental impact through appropriate changes to the river ecological water requirements that adapts to
the level of watershed ecological health.
2) Full fulfill the role of reservoir regulation to increased generating income.
By reservoir regulation, the hydropower could increase dry season capacity and reduce the amount of
disposable water in wet period. Thus Cascade Hydropower could increase earnings of hydroelectric power.
This study aims for watershed eco-health and utilization of water resources by making use of established
ecological stress function models, transforming the health objectives in the watershed ecosystem into
constraints of the annual water requirements and monthly flow processes in the river ecosystem. We now
construct the water allocation model of the watershed reservoir, assuming that the monthly eco-flow
hydrograph in the watershed is used as a basis to control the means of water allocation, with a primary goal of
long-term ecological regulation.
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The annual generation capacity (kW • h) of the cascade hydropower stations, E, can be calculated as
follows:
N T
E = max ∑ ∑ ( Ai ⋅ Qi ,t ⋅ H i ,t ⋅ M t ) (1)
i =1 t =1
The following equations represent the constraint conditions:
Water Balance Constraints:
Vi ,t +1 = Vi ,t + ( q i ,t − Qi ,t − Qei ,t − S i ,t ) Δ t
∀t ∈ T
(2)
Reservoir Storage Capacity Constraints:
Vit ,min ≤ Vi ,t ≤ Vit ,max
∀t ∈ T
(3)
Power Flow Constraints:
Qit ,min ≤ Qi ,t ≤ Qit ,max
∀t ∈ T
(4)
Eco-Discharged Flow Constraints:
Qeit ,min ≤ Qei ,t
∀t ∈ T
(5)
Power Output Constraints:
N i ,min ≤ Ai ⋅ Qi ,t ⋅ H i ,t ≤ N i ,max
∀t ∈ T
(6)
3 -1
where Ai is the integrated output coefficient of the i-th station; Qi,t is the generating flow (m ·s ) of the i-th
power plant in the period of t; Qei,t is the channel eco-discharging flow (m3·s-1) of the i-th power plant in the
period of t; for the diversion-type power station, the river ecological flow Qei,t does not pass through the
generating units, and because it is non-zero, it should be subtracted from the generating flow; Hi,t is the
average generating net head (m) of the i-th power plant in the period of t. T is the calculating total period
within a year (take the month as the calculating period, T = 12); Mt is the number of hours of the t-th period;
Vi,t+1 is the reservoir storage of the i-th power plant at the end of the t-th period; Vi,t is the reservoir storage of
the i-th power plant at the beginning of the t-th period; qi,t is the mean reservoir inflow of the i-th power plant
in the t-th period; Si,t is the abandoned water flow of the i-th power plant in the t-th period; Vi,t,min is the
ensured minimum reservoir storage of the i-th power plant in the t-th period; Vi,t is the reservoir storage of the
i-th power plant in the t-th period; Vi,t,max is the allowable maximum reservoir storage of the i-th power plant at
the end of the t-th period; Qi,t,min is the ensured minimum discharge flow of the i-th power plant in the t-th
period; Qi,t,max is the allowable maximum discharge flow of the i-th power plant at the end of the t-th period;
Qei,t,min is the ensured minimum river ecological flow of the i-th power plant in the t-th period; Ni,min is the
allowable maximum output limit of the i-th power plant; for the first i-station minimum allowed to contribute;
Ni,max is the maximum output limit of the i-th power plant.
3.2. Ecological scheduling of decision making and decision-making process for cascade
Hydropower Stations
According to utility theory [3], when making decisions on power generation revenue and river ecological
health, we must follow the principle of the biggest gains - minimum ecological damage. According to this
model, we establish the utility function U (R):
(7)
U ( R) = E − βC
in which E denotes the cascade generating capacity, C denotes the ecological loss of the watershed, and β
represents the preference of ecological health. Within the scheduling scheme, which purely pursues the
maximum generating power without considering the river ecological health, the ecological health damage
and the generating capacity are both defined as 1. Subsequently, we should treat other generating capacity of
all schemes and ecological health homogenously. On this basis, depending on the value of ecological health
preferences we calculated for each value of the utility function. Then choose the maximum utility value of
the program as a balance between generating income and ecological health of rivers cascade operation of the
program.
Based on the above principles and methods of decision-making, the ecological decision system functions
can be divided into calculation of ecological flow, ecological scheduling and decision-making of ecological
scheduling. The relationship between functional modules as a unified whole coupled according to procedure.
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4. System Integration Solution
System Integration solutions abide by the following several important principles.
1) Advanced principles: developed system must reflect the latest Internet technology to make full use of the
Internet.
2) Practical principles: developed system based on practicability could provide a high real-time analysis
and calculation tools which could be able to provide strong data mining for decision support.
3) Maintainable principles: through the use of all applications on the server, cloud computing could greatly
reduce the maintenance.
4) Reliability principles: system must have high reliability and stable operation. It is important to provide a
unified data center security and redundant data storage capacity.
5) Security principles: production and operation data is the key to the business. System must provide multilevel security mechanisms to protect the security of data Including data access security and storage
security.
6) Extendibility principles: system should have an open structure whose interface complies with
international standards to meet the application requirements to upgrade and integrate other systems.
Based on these principles, the system was constructed with the principle of hierarchy. Hierarchical
principles include two aspects of meaning that is logic level and functions level:
Logic layer, presentation logic (View), business logic (Model), control logic (Controller) in the system is
separated into three different layers. It was known as view - Model - Controller (MVC) framework. View
layer is in charge of the user interface and information input and output. Model layer is in charge of enterprise
data processing system and business rules. Controller layer is in charge of accepting user input and calling the
model and view to fulfill the needs of users. Hence this system can provide good scalability.
From system function perspective, the cascade hydropower ecological scheduling decision support system
is divided into three levels, namely, the system layer, the platform layer, the business layer. The platform layer
can be further divided into three sub-layers, namely, security services, cloud computing support services,
public services. Business layer can be further divided into four sub-layer, namely, the basic data, ecological
flows, ecological scheduling, ecological decision-making.
That described as follows, respectively:
The system layer provides network infrastructure services include network and remote communication
services, data access services, basic security services, news services, etc in distributed network.
The platform layer promotes seamless integration between the various application modules through the
workflow engine and web services support and other public service facilities.
The modules in platform layer include:
Workflow engine: workflow engine directly support the application layer to automate various business
processes and standardized implementation. It supports business process Reengineering[4,5].
Cloud computing: to achieve SaaS architecture, the platform layer provides data exchange adapter service,
SOAP, WSDL, UDDI Registry Service[6-8].
Security Services: the platform layer provides authentication, access control, storage encryption and
transmission encryption, anti-repudiation, authorization management, security and auditing functions.
Business layer: business layer provides a variety of business rules and logic implementation based on ecoscheduling decision-making requirements. Details including:
Basic Information services is responsible for the entire system based data storage, maintenance, and
display.
Ecological flow calculation services provide analytical services for flood forecasting, river ecological
water requirements computing services.
Scheduling and decision support services provide the reasonable optimal scheduling according to
hydrological and ecological water requirements of river conditions. The structure was shown in Figure 1.
5. The Critical Technologies Adopted in System
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5.1. Rich internet applications（RIA）
RIA is a new type of internet application which combine the advantages of desktop applications with
merits of web applications, such as interaction, immediate deployment, cross-platform, maintenance-free
features. RIA simplify and improve the web application's user experience. thus applications can provide
richer, more interactive and responsive user experience.
A united access interface based on RIA
Core business
platform
Support
System
platform
General
informa
tion
Compon
ent
Manage
ment
safety service
ecologic
al water
requirm
ents
Runoff
forecast
Ecoschedu
ing
Web Service
Ecologic
al
decision
-making
User
manag
ement
Business
Process
management
Ssytem security
Sysytem management
Application
platform
Windows Server
SQL Server/Oracle
Arc GIS Server
IIS
Fig. 1: The structure of DSS
For ecological scheduling system, the deployment of RIA has the advantage of using existing application
model without replacing the existing web applications. By RIA technology, you can easily build more
intuitive, easy to use, more responsive and can use the application offline.
RIA technology can help companies achieve a wide range of important business benefits including
interactive data analysis, increased ability to raise the level of decision support, reduce bandwidth costs,
reduce support for help and enhance user experience, etc.
System RIA platform built by Flex Builder 3.0. Flex Builder was a server side application framework
which developed to meet the requirements of enterprise-level programmers. Flex Builder provides a
standards-based, declarative programming methods and processes, and provides runtime services for
developing and deploying rich client application layer. Flex developers use XML-based visual MXML to
define rich user interface. The language compiled as SWF format by the Flex server. The client application
run in browser-based flash player plug-in.
5.2. Cloud computing
Cloud computing is a new method of using Internet resources. Cloud computing relying on the Internet
heterogeneous, self-service can provide computing on demand for the people. As the resources on the Internet,
and in the flow chart of the computer, often expressed in a cloud-like pattern. So you can visualize analogy to
cloud computing."Cloud" is also on the underlying infrastructure of an abstract concept.
Cloud computing can be considered include the following levels of service: IaaS, Infrastructure as a
Service, PaaS, Platform as a Service and SaaS, Software as a Service. Cloud computing services typically
provide universal access through the browser's online business applications, software and data can be stored in
the data center.
The ecological scheduling system uses one-level cloud computing that is SaaS.
This type of cloud computing interact with the user program through a browser. From the user point of
view, this will save on the server and software license expenses. From the developer point of view, it need
only be enough to maintain a program, this can reduce costs.
All of the computing in ecological scheduling system are used to achieve in the clouds published by Web
Services. The services accessed by the user through the browser. All software and data are located at the data
center server. Facing changes in ecological conditions, if the original Web Services only change the internal
algorithm, then the system only need to rewrite and compile the part of the concrete implementation of Web
services without changing the whole system. Only the interface changes or additional features, the new Web
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service could be embedded into the system. This technology enhances the system scalability to meet the
requirements of flexible of ecological constraints .
6. The Application and Prospects of Eco-Scheduling System
This paper discusses the principles, methods, techniques in ecological scheduling decision support system
on the Yalong River Basin. In this study, the ecological scheduling system based on B/S mode developed with
Flex Builder. It enable authorized users to fulfill the process of ecological flow calculation, calculation of
ecological operation, ecological scheduling and decision-making. The system put into operation in 2009.
Figure 2 is a typical interface of the system.
Hydropower construction has transitioned into a phase dominated by ecological constraints. How to
effectively reconcile the contradiction between river development and environmental protection has presently
become the most urgent issue related to the construction of hydropower projects. The arising Internet/Intranet
network technology provides an unprecedented opportunity for the hydropower scheduling decision support
system to making sciences, efficient and reliable decision. Scheduling for the system of ecological principles,
ecological decision-making decision-making process, based RIA platforms and cloud computing systems
development and other issues, this paper gives a preliminary answer. But how to design a better system
integration solutions for the practical application of new technologies need more research and discussion.
Fig.2: Interface of the generation scheduling system
7. Acknowledgment
This study Supported by Ministry for the Environment Foundation of China(2008467086)
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