In
April 2003, the ¡°Instructions on the Technical Modernization
of Rural Hydro¡± was issued by the Ministry of Water Resources,
which clarified the technical direction for the development
of the rural hydropower sector in the years to come in order
to quicken the pace of modernization for China's rural hydropower.
The document pointed out the direction for standardizing and
guiding the rural hydropower sector for technical advancement.
The overall objectives are, prior to year 2010, 50% of rural
hydropower plants and their power grids should be modernized,
and in 2015 the rural hydropower sector should be all modernized.
Through scientific and technical innovation and management
improvement, the competitiveness of the rural hydropower market
should be noticeably improved.
The ¡°Instructions on the Technical
Modernization of Rural Hydro¡± bring out some objectives and
requirements as follows:
(1) Rural hydropower plants
--- Much attention should
be paid to the cascade and rolling development of a certain
basin, and the cascade hydropower station should be designed
and built according to the comprehensive programming of this
basin. Priority should be given to develop those hydropower
stations with at least seasonal regulation capability, and
pumped storage power plants should be developed as appropriate.
--- New hydropower plants
should be designed and constructed according to the requirements
of unmanned control and operation (or with a few operators
on duty). Those stations built before the 1990s should be
programmed for renovation or upgrading in line with the overall
objectives. Generating units past their service life and that
cannot meet the requirements even if technically upgraded
should be discarded for rebuilding or forcibly put out of
service.
--- Integrated planning and
design should be carried out for the renovation of hydropower
plants. The output and efficiency of units can be improved,
and service life extended through improvements to the hydraulic
structures, adopting a high efficient anti-cavitation and
abrasion-resistant runner, upgrading the generator insulation,
bettering its cooling conditions, applying SCR or brushless
excitation technology, gravity butterfly valve and plastic
tiles. Meanwhile, the automation of hydropower plants can
be improved by renewing or renovating the supervision and
control devices and the automation components.
--- New high-efficiency turbine-generator
units should be applied. The suitable type of unit should
be selected according to different water heads and discharges.
For the detailed selection method and principles refer to
¡°The Runner Type Series of Medium and Small-scale Kaplan and
Francis Turbines¡± (JB/T6310-92), and ¡°The Type Series of Cross-flow
Turbines¡± (JB/T7640-94), and also consider the existing proven
runners of manufacturers.
--- Hydropower plants with
total installed capacity of 5 MW and above should use open
and distributed computer-based supervision and control system.
The governor, excitation device, and the oil, water, air and
D.C. systems inside the plant, and gates should adopt microcomputer-based
systems for their supervision and control. The digital communications
between the computer-based supervision and control system
and the control units of devices can be carried out through
the main communication line at site, serial communication
or I/O modes.
--- For hydropower stations
with total installed capacity of 5 MW or less, the centralized
and decentralized computer-based supervision and control system
should be combined together. The DC system should communicate
with the computer-based supervision & control system.
The governor can adopt microcomputer-based type or oil-pressure
actuator. The supervision and control for the in-plant oil,
water, air and other systems can adopt simple-structured automatic
relay control devices.
--- Inside hydropower plants
with a generator voltage of 400 V, the simpler integral compact
supervision and control system should be adopted. Energy-storage
for the turbine¡¯s actuator can be chosen to be in the form
of high-pressure nitrogen cylinder or high-pressure oil. Standardized
hydraulic components should be adopted to reduce the maintenance
cost and the space occupied.
--- The oil, water, air systems
and other auxiliary devices inside the plant should be integrated
with the main machine for their control, so non-maintained
of easily maintained devices or equipment are preferred.
--- Inside a power plant,
the automation components will play a key role in the unmanned
operation of this station, so mature, qualified products which
also reach national standards and are fit to be operated in
a humid environment should be selected for application. Meanwhile,
much attention should be paid to improving the working environment,
which must meet the requirements specified in the operation
manual. For the oil-water mixture sensor, the liquid-level
transducer, the flow transducer, the pressure transducer and
the position transducer, those products with 4-20mA modular
output or serial communication interface should be selected.
For hydropower stations with a relatively large capacity,
a gear type and/or the residual voltage should be adopted
for speed measuring. The pressure and the liquid-level transducer
should adopt a kind of integral structure in which the capacitor
type or the diffusive-silicon piezo-resistor is combined with
a special signal amplification circuit. The 4-pass ball valve
is recommended as the multi-passage electromagnetic valve,
and the electromagnetic valve for cooling water should be
of the active thermal diffusion type. Cu50 or Pt100 should
be used for the temperature sensor, and the temperature data
logging devices should be equipped with RS485 or RS232 communication
interface.
--- In rural hydropower plants,
the main electrical connection should be as simple and reliable
as possible. Products with high reliability, low fault occurrence,
low maintaince requirement, or even non-maintaince properties
should be selected for use as the main electrical devices.
Examples are the new type energy-saving transformer used as
the main transformer, the dry type transformer adopted as
the excitation transformer or the plant-service transformer,
the vacuum circuit breaker or the SF6 circuit breaker and
the zinc oxide lightning arrester. In summer there is serious
condensation inside the power plant, so a generator with F
or above insulation grade should be adopted. For those rural
hydropower plants located in the hilly areas, there are many
occasions for them to be attacked by lightning, so much attention
should be paid to mitigating lightning attacks, and earthing
design and construction.
--- Microcomputer-based auto
quasi-synchronizing device or the microcomputer-based relay
protection device should be adopted.
--- Digital or impulse type
electrical energy meters are recommended for metering the
electrical energy of the hydropower plant.
--- For hydropower pants
with a large capacity, the fibre-optic digital instrument
transformer and its new automation technology with a low
volume and strong anti-interference capacity should be actively
recommended.
--- As for hydropower stations
equipped with a computer-based supervision and control system,
the database structure should be of open type, and through
reserving communication interfaces and using standard communication
protocol, the requirements of dispatching automation can
be met, and remote terminal unit (RTU) are not necessary.
--- The computer-based
supervision and control system inside the hydropower plant
should gradually lead to economical operation of the whole
station, and cascade power stations can realize optimum
dispatching among different cascades. At the same time,
communication interfaces should be reserved for connections
with other systems (such as water regime forecast, dam safety
detection, visual supervision and control, fault diagnosis
and status inspection), so that data sharing and information
management inside the whole plant can be achieved.
--- The structural design
of the powerhouse should gradually move towards standard
modules, and the building style, form and internal and external
decoration must be compatible with the surrounding environment,
and aim to beautify the environment and develop tourism.
The power plant should be sealed against dust, pests and
small animals. During the construction period, the gate
in the powerhouse for equipment access should have a framework
structure and adopt lightweight removable materials. A permanent
large gate should then not be designed any more, and all
these gates can be blocked after construction. The arrangement
of secondary panels and cubicles is a challenge to the traditional
design mode, and a transparent closed equipment corridor
can be built. When renovating old plants, attention should
be paid to adopt the same panel shape and same color.
(2)
Dispatching automation system
---The plan for the dispatching
automation system should be formulated according to the
development program of the local power grid, and for the
master station, communication channel and remote terminal
unit (RTU) of the dispatching automation system, the function
requirements, technical norms, equipment (hardware/software)
programming and the step execution plan should be drawn
up.
--- The basic functions
of a dispatching automation system include the system control
and data logging (SCADA), and the management and application
functions for the dispatching operation should be taken
as a selection. When selecting these functions, the actual
demands on management should be taken into account. Status
estimation, current calculation, line loss analysis, load
forecast, fault analysis, safety analysis and reactive power
optimum operation and management and other high-level applied
software should be configured where relevant, and also put
into practice.
--- When selecting the
system platform, the operation conditions of the system
platform which has been put into use in that area should
be examined, so as to meet the demand of inter-communication
among systems. Hardware equipment with superior properties
and low price should be selected, to ensure the system is
highly safe, reliable, practical, open-structured, extendable,
easily-applicable and flexible.
--- The dispatching automation
system should adopt a standard communication protocol, and
it is suggested to adopt the professional standards of China¡¯s
power industry, ¡°Standard of Basic remote control Tasks¡±
DL/T634-1997 (equivalent to IEC-60870-5-103 protocol), the
¡°Circulating Remote Protocol¡± (DL451-91) and the ¡°Application-level
Protocol on the Real-time Digital Communication of Power
System¡± (DL476-92).
--- For some counties which
plan to construct a distribution automation system at the
same time, the scheme for the integration of dispatching
and distribution should be considered, and for others which
plan to set up a distribution automation system in the next
few years, consideration should be given to including capacity
in the dispatching automation system for extension to the
distribution automation system.
--- The dispatching automation
system should be able to interface with the dispatching
information management system and the distribution automation
Master station, and meanwhile, it can be connected to the
management information system (MIS), the water-regime measuring
and forecast system, and the dam safety monitoring system,
and its interface safety should meet the requirements of
the ¡°Safety of the Computer-based Supervision and Control
System and the Data-dispatching Network in Power grids and
Powerplant¡±, to ensure the safe operation of the power grid.
(3)
Other matching power grids
--- Building a high-voltage
power grid mainly based on 110 kV network, with reasonable
structure and simple and reliable arrangement, and which
is also flexibly operated with adequate power supply capacity
is suitable for meeting the long-term demands of load increase
and rural hydro development.
--- In cities the arrangement
of 10 kV dispatching power grid should adopt a looped network
structure with double power sources, which can be operated
under open loop. The distribution network located in rural
areas will still mainly adopt a radiative structure. A main
line or a sub-line which is relatively long should be equipped
with a tap changer or branch switch, and other switching
and control devices should be actively applied such as the
intelligent looped network cabinet (RMV), the automatic
recloser, the automatic sectionalizer, the feeder remote
terminal unit (FTU) and the transformer mesure and control
unit (TTU), so as to realize feeder automation.
--- The trend for rural
substation is to develop as a small outdoor structure, and
in cities, a containerized compact substation can be adopted.
--- New substations to
be built should be designed in line with the requirements
of unmanned operation, and the aged ones should be gradually
refurbished with automation systems to achieve unmanned
control (or fewer operators on duty). Priority should be
given to the use of a comprehensive automation system with
hierarchical structure to meet the measurement, protection,
control, regulation and communication demands of substations.
Standard communication protocols should be applied among
the units themselves, and between the substation and the
dispatching unit. (For any special communication protocol,
the detailed text should be provided). Additionally, attention
should be paid to the compatibility, expandability and the
upgrading capability of the software and hardware.
--- An unmanned control
substation may not be equipped with a fixed main computer,
but at site there should be some interfaces reserved to
connect to the main computer for commissioning. If necessary,
a perimeter alarm system and a visual surveillance system
can be installed.
--- As for substations
with voltage of 35 kV and above, the energy-saving on-load
regulation transformer should be extensively applied. The
distribution transformer should be of the low energy-consuming
type with superior technical properties, or a completely
sealed transformer or an amorphous alloy transformer. The
high-energy-consuming transformers that the government has
ordered to be put out of service should be replaced in the
next few years.
--- For newly built substations,
the vacuum circuit breaker, SF6 circuit breaker or other
advanced switch equipment should be adopted in line with
the voltage grade, and oil switches should no longer be
adopted. 35 kV and 10 kV voltage and current transformers
should be of resin type. For the voltage levels of 110kV
and above, gas-insulated switchgear (GIS) can be selected
for use. The oil switch devices used in early times should
be discarded gradually.
--- According to the system
requirements, a reactive compensator with suitable capacity
should be reasonably installed, and a reactive auto voltage
control device should be erected.
--- The use of microcomputer-based
protection devices and microcomputer-based auto safety devices
should be popularised.
--- The use of zinc oxide
lightning arrestors should be popularised.
--- The distribution cubicle
integrating functions such as protection, control, metering,
reactive compensation and lightning protection should be
adopted for the distribution system in cities.and towns.
--- Optical-fibre digital
instrumental transformers, optical-fibre digital substations
and other new technologies should be popularised.
(4)
Distribution automation
--- Pilot projects of
distribution automation should be actively tried out, and
then applied extensively. The distribution automation scheme
and its equipment should be selected according to the local
economic development, load type and its requirements on
dependability. Priority should be given to the SCADA system,
the distribution automation (DA) of feeders, automatic mapping/feeder
management/geographical information system (Am/FM/GIS) and
the remote meter reading system.
--- In the distribution
automation system developed at the initial stage, attention
should be paid to the selection of the operating system,
the database management system and the network system with
excellent open characteristics, and in design, some principles
should be noted, such as standardization, openness, integration
and expandability. Equipment with modularized design should
be adopted as far as possible, and the demand for standard
interfaces to expand and upgrade functions should be met.
--- The design for the
master station of the distribution system should abide by
the national or professional standards, and it should be
endowed with superior properties such as safety, reliability,
practicality, expandability, openness, fault-tolerance,
and meeting the requirements of the power system for real-time
performance. In principle, it should be designed integrally
with the dispatching automation system, and interfaced with
the management information system. The data exchange among
various systems should observe a unified interface norm,
so as to use the same information sources, mutually share
the information and simultaneously renew the figures and
data. Before the dispatching automation system has been
set up, the distribution automation system should not be
implemented in advance.
--- The remote meter reading
system should be initially carried out, and then gradually
popularized if practical. The communication channels of
the remote meter reading system should be considered as
a whole when planning the communication channels of the
power grids, so as to try to realize their mutual sharing,
and additionally a certain development in the future should
be considered.
(5)
Information management
--- The management information
system (MIS) consists of production, finance, manpower resources,
power sales, office automation and other sub information
management systems, and much attention should be paid to
practicality and compatibility when developing the software
of such systems. Therefore, it is suggested to adopt object-oriented
technology, so that the software can adapt to changes in
organization structure, management mode and operation flow,
and extend the life span of the software system.
--- Enterprise resources
planning (ERP) should be popularized, and the ERP platform
should be set up with the full use of the information from
MIS and SCADA systems. The technical support system of the
power market could be initially adopted, so as to meet the
requirements of ¡°price competition for selling to the power
grid¡±, reduce the operation costs of enterprises and improve
the economic benefits.
(6)
Communication system
--- The communication
system should meet the demands of the power system for its
safe and economical operation, and surplus capacity should
be suitably set aside to meet the requirements for expanding
new communication businesses.
--- The design of the communication
system should stick to the principles of being advanced,
openness, safety, expandability and practicality. This system
should adopt the mainstream technology and mature products,
and can be suitably state-of ¨Cthe -art. The network and
equipment should support the standard interfaces, and extensively
applied standard protocols should be selected so as to realize
reliable interconnections with other systems concerned.
The key parts of the system should have redundancy. The
communication devices and the power source should be highly
reliable, and be able to support the smooth upgrading of
the system, and meanwhile, it must be guaranteed that business
will not be affected during network expansion. The system
should be simple to operate, easy to maintain and convenient
to manage. For the sake of meeting business demands, the
optimum performance-cost ratio should be reached.
--- Key networks should
adopt optical fibre for communication as a first priority,
and the branch communication network should mainly adopt
power line carrier technology. When the cost-performance
ratio is very good, then the wireless spectrum-spreading
device is recommended, with the telephone channel taken
as standby.
--- Inside the communication
network, the exchange, transmission and interfaces should
all conform to the national standard, ITU-T norms or other
related professional standards.
--- During the construction
of the communication network, safety measures should be
adopted accordingly, so as to meet the requirements specified
in ¡°The Safety of the Computer-based Supervision and Control
System of Power Grid and Power Plant, and the Data-dispatching
Network¡±.
