China`s SCADA/EMS market growing rapidly
China`s electrical power industry is growing rapidly; older SCADA/EMS systems have to be expanded and improved and new ones added; vendors must be aware of Chinese requirements
Electrical Power Planning & Engineering Institute, Ministry of Electric Power
China`s electric power industry is growing rapidly. The total installed generating capacity is increasing at the rate of 8 percent to 10 percent annually (Figure 1). More than 10 million kW of new units are installed each year.
In 1994, the total capacity for China was 193.3 GW and generating about 905 billion kWh.
Some 25 percent of the units are hydropower. The largest units are: 900 MW nuclear, 600 MW thermal and 300 MW hydropower.
The transmission system consists of 500- /220- /110-kV lines for most of China, but the Northwest Power System uses 330- /220- /110-kV lines. Table 1 shows the summary of lines, substations and transformer capacity by voltage class.
There are five regional power systems and 10 independent provincial power systems in China, including the Northeast, North China, East China, Central China and Northwest Power System. The 10 independent power systems include Shandong, Fujian, Guangdon, Guanagxi, Hainan, Sichuan, Yunnan, Guizhou, Zinjiang and Tibet Power System.
Several years ago, Central China Power System and East China Power System interconnected their systems via a ?500-kV dc transmission line and formed a large power pool with a total capacity of 54 million kW.
Another interconnection involves four independent provincial systems: Guangdon, Guanmgxi, Yunnan and Guizhou Power systems. These systems are connected via two 500-kV lines and one 220-kV ac line. This system has 24 GW of capacity.
The Guangdon Power System is also connected with the Chinese Power Co. in Hong Kong via Daya Bay nuclear power station.
Table 2 lists the installed generating capacity, energy produced and hydro-power ratio for each of the regional and provincial power systems All of the Chinese power systems are expected to be interconnected by the year 2000, except Xinjiang and Tibet.
The power system management organizations and their control centers are set up with five layers of hierarchy: National Control Center (NCC), Regional Control Center (RCC), Provincial Control Center (PCC), District Control Center (DCC) and County Control Center (CCC). Their duties and responsibilities include:
– NCC–responsible for power flow management of intertie lines between RCCs, coordination of system operation, long- and middle-range planning of power, and energy balance of the whole country. Security and economic statistical analysis to all systems in China.
– RCC–responsible for load forecast, power and energy balance, generating planning, automatic generation control and economic dispatch, reactive power and voltage regulation in this region, and power flow schedule on intertie lines between provincial systems. It is also in charge of operation of large power plants and high-voltage (500-kV and some large 220-kV lines) substations and keeping the frequency at 50 Hz.
– PCC–responsible for keeping power flow on intertie lines on schedule and operation of high-voltage (220-kV and some 500-kV lines) substations according to the requirement of RCC to PCC.
– DCC–does load control and feeder switching and regulates voltage level to meet customers` needs. It is also responsible for operation of equipment in the 35- to 220-kV substations within the district.
– CCC–responsible for load control, feeder switching, keeping voltage level to meet customers` needs and operating the equipment in the 10- to 110-kV substations in this county.
Because the system management is organized by administrative division and by voltage level, there is cross management in power stations and substations. In a 500- /220-kV substation, for example, the 500-kV equipment is dispatched by RCC, while 220-kV part is dispatched by PCC. Data collected from a substation must be sent to RCC and PCC.
Currently, NCC only controls one dc line between Central China Power System and East China Power System. It will dispatch high-voltage transmission lines between regional systems and extra-large power plants, such as Three Gorge hydropower plant. This will take place in the year 2000, when regional land independent provincial systems are interconnected to each other.
In China, the NCC, RCCs, PCCs and most district systems have been equipped with SCADA systems, but their size and function are a bit different.
NCC has a new SCADA system based on SUN workstations and open-system architecture imported from Siemens, Germany. Put into operation in 1993, it collects real-time information from RCCs and independent PCCs by means of computer communication links and package switching network.
NCC uses this system to monitor the regional systems, provincial systems and dc intertie line operation. It also does statistic analysis of operation information all over China.
This information can be printed out daily, weekly, monthly or as a yearly report. The SCADA system in NCC is the first open system operated in China.
RCCs and PCCs have SCADA systems imported from ASEA, Sweden. These systems were put into operation in Hubei PCC in 1982. This system has worked quite well, but it cannot completely meet the need of dispatchers in Hubei`s PCC because it has no Chinese characters for display or printout. However, it will be upgraded to a new EMS system in the future.
SCADA systems have been imported from various vendors, including Westinghouse in Great Britain, ABB Systems Control, Siemens Empros (CDC, Texas Instruments, and Ferranti of the United States and Canada). However, these imported systems have no Chinese characters in the display or in the reports. In addition, they cannot interface with domestic cyclic data transmitting RTUs, which are widely used in China.
These problems are being worked out, but for now, there are no turnkey SCADA projects in China.
The Ministry of Electrical Power is working through Chinese research groups to develop its own SCADA systems. Nanjing Automation Research Institute, China`s Electric Power Research Institute and other units have developed domestic SCADA systems. Last year, Heilongjian and Fujian PCCs purchased new SCADA/EMS systems based on IBM R6000 workstations with open-system configuration from Siemens Empros.
China uses what is called the “walk on two legs” policy, which means, when advanced SCADA/EMS systems are imported, China develops its own systems as well.
Recently, two systems were developed by NARI. One, the RD-800 is based on SUN workstation with open-system configuration. Another is the SD-6000 based on the DEC Alpha workstation with the same configuration.
Special requirements for China`s SCADA/EMS systems include:
– the MMI system must have Chinese characters and
– the data acquisition processor (or front-end processor) system and RTUs must interface and process data
When data are being transmitted from RTU to the master station, a good performing modem and data-coded distance equal to four or higher is required. Two channels (hot and standby) are used in large power plants or 330-kV and 500-kV substations. Autoswitching between hot and standby channels is required.
The main problems still to be solved in China`s SCADA systems are:
– defects in the automation executive devices
– unreasonable energy price
– imperfect management system and
– shortage of electricity.
The application of SCADA/EMS is a bit low, but China has plans to increase the use of these systems. Unfortunately, there is a shortage of application software for security, optimization of operation and management at present.
Zhijian Tang graduated from Chongqing University in 1954. From 1954 to 1975 he was engaged in system planning and engineering. Since 1976, he has worked as an engineer; senior engineer; and chief of System Planning Department of EPPEI–responsible for reviewing and approving SCADA/EMS projects and telecommunications systems in China. Tang is a member of the Chinese Society of Electrical Engineering.