2 Terms
2.0.1 Urban distribution network
An electric power network which receives electricity from power transmission networks and then distributes it to urban consumers.Urban distribution networks consist of HV，MV and LV levels.Urban distribution networks usually refer to networks rated 110kV and below.In urban distribution networks，35kV，66kV and 110kV networks are HV networks，l0kV and 20kV networks are MV networks，and 0.38kV network is LV network.
2.0.2 Saturation load
The maximum load that an urban or a regional network can reach within planned years and is basically stable within certain years.It shall be formulated according to the urban or regional long-term development plan and power demands.
2.0.3 Distributed generation
A power generating facility that can provide power，heat or cooling，located near power loads，with high energy efficiency and environmental compatibility.
2.0.4 Economic evaluation
Economic evaluation involves financial evaluation and national economy evaluation.The economic evaluation of distribution network planning mainly means analysis，demonstration and comprehensive assessment of financial feasibility and cost-effectiveness of distribution network plans through scientific methods according to the city's economic and social development and regional power network development，for the purpose of determining the best plan for development of urban distribution networks.It is an integral part of distribution network planning and a key criterion to determine the plan.
2.0.5 Financial evaluation
The calculation of financial benefits and costs from development plan perspective，analysis of their profitability and liquidity，and assessment of their financial feasibility under the nation's current financial，tax and price system.
2.0.6 National economy evaluation
The calculation of contributions of plans to national economy，analysis of their economic efficiency，effectiveness and influence on the society，and assessment of their reasonableness in respect of macroeconomy，from perspectives of the nation's economic benefits on the premise of rational allocation of resources.
2.0.7 N-l security criterion
In normal operation，when any element in a power system is disconnected without faults or due to faults，the system maintains stable operation and normal power supply，other elements are not subject to overload，and the system voltage and frequency remain within the allowable range.The ability and extent to which the system maintains stability and continuous power supply is referred to as"N-l"criterion.N is the number of relevant lines or elements in the system.
2.0.8 Capacity-load ratio
The ratio of total rated capacity of substation equipment in a given service area of a distribution network to the maximum mean active power of loads served by such equipment.Reflecting the operating margin of substation equipment，capacity-load ratio is an important indicator for macro-control of total substation capacity in urban power network planning.
2.0.9 Underground substation
A substation built underground，whose main buildings are constructed independently or combined with other buildings（structures）.It consists of fully and partially underground substations.
2.0.10 Fully underground substation
Main buildings of the substation are built underground and the main transformers and other main electrical equipment are installed in underground buildings.Above the ground level only a few buildings are arranged，such as the ventilation openings and equipment，entrances/exits as well as the cooling equipment of large-sized main transformers and main control room possibly located above the ground level.
2.0.11 Partially underground substation
A substation where most of the buildings are built underground and the main transformers and other main electrical equipment are installed in aboveground buildings.
2.0.12 Special consumer
A consumer who causes adverse effect on the power system and equipment，and serious hazards to other consumers.Special consumers include distorted，impact，fluctuating，unsymmetrical and voltagesensitive consumers as well as those who have special requirements on electricity quality.