What Is Native Capacity?

Installed capacity, the full name is "power plant installed capacity", also known as "power station capacity." Refers to the sum of the rated power of all steam turbines or hydroelectric generating units installed in a thermal or hydroelectric power plant. It is one of the main indicators to characterize the construction scale and power production capacity of a thermal power plant or hydropower station. The unit is "kW". The installed capacity should generally be considered by the electric power design institute or other relevant technical departments for a variety of different schemes according to the local objective conditions at the time and the needs of the power industry construction and development plan. Comparison can be determined. In addition, the total installed capacity of all thermal power plants, hydropower stations and other types of power plants in the entire power system is also referred to as the "installed capacity" of the power system.

The installed capacity refers to the rated active power of the generator set actually installed in the system. The installed capacity of 2 * 150,000 kilowatts is two 150,000 kilowatt generating units. The theoretical power generation per hour is 150,000 kilowatts. For example, the installed capacity of a power station is 1 million kilowatt-hours, with a loss of 35%, generating 650,000 kWh in one hour, 1.5 million hours can generate 1 million kWh, and about 39 million kWh a day. The general unit MW means megawatt, 1 megawatt (MW) = 1000 kilowatts (KW), 150MW = 150,000KW is 150,000 kilowatts. 150MW refers to the power of a generator that can generate 150MW of electricity per hour. According to popular terms, it is generating 150,000 degrees per hour. We all like to call this unit a 150,000 kilowatt unit. 2X150MW is to build two 150,000 kilowatt units. ^[1]

The sum of the nameplate capacity of the hydroelectric generating set of the hydropower station. It is one of the most important characteristic values of a hydropower station. The capacity of a hydropower station in operation, standby, and maintenance is called working capacity, standby capacity, and maintenance capacity, respectively. The sum of the three is called the required capacity. Sometimes, in addition to the necessary capacity, increasing the installed capacity of hydropower stations has the effect of generating more seasonal power during the flood season, replacing thermal power, reducing the fuel consumption of the system, but not reducing the installed capacity of the power system. This part of capacity is called repetitive capacity. In different hydrological years and seasons, as the operating status of the hydropower station and the requirements of the power system for the hydropower station are different, these capacities are different, and under certain conditions, they can be converted to each other. The working capacity is the active power that is issued when the hydropower station is responsible for the load system of the power system. The daily maximum working capacity of the hydropower station is related to the average daily output, the system load, and the ability to perform daily adjustment. The working capacity is large during the high water season and the load, and the corresponding reserve capacity can be smaller; during the dry season and the system load is small, the working capacity is small, and the standby capacity can be larger. The maintenance of hydropower generating units is usually arranged in the dry season, so the maintenance capacity in the dry season is large. During the operation of the power system, due to load changes, some capacity may not be used, and it may be in an idle state. This part of capacity is called free capacity.

When the working head of a hydropower station is less than the rated head of the unit, part of the installed capacity cannot bear the necessary capacity, which is called blocked capacity (see rated head of a hydropower station).

The installed capacity of a hydropower station depends on the load and characteristics of the power system, the energy index of the hydropower station, the regulation performance of the reservoir, the status and role of the hydropower station in the system, and its technical and economic characteristics.

Energy index of hydropower station Energy index includes guaranteed output and multi-year average annual power generation, which is the basis for determining its installed capacity. Hydropower stations use their energy to participate in the power-electricity balance of the power system in order to verify the benefits of their capacity and power.

The status and role of hydropower stations in the system The status and role of hydropower stations are determined by the hydropower station s energy distribution, load characteristics, power supply composition, working position of the hydropower station on the system daily load chart, and the size of the reserve capacity of the system. When the energy is constant, the more energy the hydropower station allocates in the month of large system load (the month of capacity balance control), the larger its installed capacity; the closer the working position of the hydropower station on the daily load chart is to the peak, that is, the working hours of the hydropower station in a day The smaller the number, the more peak-shaving tasks and the larger the installed capacity, but the number of hours a hydropower station works in a day depends on the peak duration of the power system; the more standby capacity a hydropower station has, the larger its installed capacity. Therefore, the installed capacity of hydropower stations is much larger than the guaranteed output, and the ratio of the installed capacity to the guaranteed output often reaches 2 to 5, or even larger.

The status and role of hydropower stations in the system are restricted by their regulating capabilities. Only those hydropower stations with seasonal (annual) adjustment capacity can distribute their energy to the month with a large load and be able to bear the accident reserve. Only a hydropower station with a daily regulation capacity or more can bear the peak load of the system's daily load and the load reserve. Hydropower stations with incomplete daily regulation capabilities, no regulation, or downstream base load requirements for shipping can only bear the waist load or base load of the system daily load, respectively, and the installed capacity is limited accordingly.

Technical and economic characteristics of hydropower stations Compared with thermal power plants, hydropower stations start and stop quickly and operate flexibly, which is suitable for peak load regulation and the system's reserve capacity. When the dam height is set, the cost of increasing capacity is lower than that of thermal power plants (about 1/2 of the power plant). Increasing the capacity can increase the power generation correspondingly, thereby saving thermal power fuel. Therefore, under certain conditions, increasing the capacity of a hydropower station is more economical than that of a thermal power plant. Therefore, the annual utilization hours of installed capacity of a hydropower station (ie, the ratio of the average annual power generation to the installed capacity for many years) or the annual load factor of the power station (divided hours of installed capacity by 8760) are generally smaller than thermal power plants. When the hydropower station with better regulation performance and the proportion of the system's hydropower is not large, its installed capacity can reach 2000 or less per year. When the regulation performance is poor and the proportion of hydropower in the power system is large, the annual utilization hours of the hydropower station can be more than 5000.

Selection of installed capacity The conventional method is to formulate different installed capacity and installed program schemes for hydropower stations, and to compare them technically and economically. The selection should include transmission lines and transmission losses related to installed capacity. When several power stations are put into operation during the planning period, the installed capacity of the hydropower station group can be selected. The conventional method is to first select the comprehensive installed capacity of the hydropower station group, and then to allocate the installed capacity between the hydropower stations. The technical and economic factors affecting the distribution of installed capacity of hydropower stations are: The installed capacity of power stations with long transmission distances should be smaller. The peak diversion performance of the power station with a long diversion channel is poor, and the cost of increasing the capacity is large. The installed capacity should not be too large. For power stations with comprehensive utilization restrictions (such as shipping base load requirements), the installed capacity will be limited. The installed capacity of a power station with a large amount of increased power generation capacity should be appropriately large. Increasing the capacity of ground power plants is more favorable than increasing the capacity of underground power plants. The installed capacity allocation of cascade power stations should take into account the needs of capacity coordination and operation. In order to compensate the need for adjustment, the installed capacity of some power stations should be appropriately increased.

The optimization method is to apply the optimization model to optimize the installed capacity of hydrothermal power stations in the planning period, including the installed capacity and yearly installation procedures. The model can be constructed using dynamic programming or (and) linear programming. (See Optimization of Water Energy Utilization)

Due to the increasing load of the power system and the interconnection of the power system, some hydropower stations with good regulation performance have changed their role and status in the power system. From the original construction, the power generation was mainly to the capacity efficiency. The thermal power in the system was large. The number of generating units and nuclear power units is increasing, and the energy index of hydropower stations may be greatly improved with the implementation of cascade adjustment and cross-basin compensation adjustment. Reasonable installed capacity of hydropower stations should increase with time. Many hydropower stations in the world have adopted the construction plan in stages, or expanded after several years to expand the installed capacity. China also has some hydropower stations with better regulation performance. After several years of construction, the expansion or the feasibility of expanding the installed capacity is being studied. ^[6]