1 General
1.0.1 This standard is formulated to regulate the design of photovoltaic power generation access distribution networks and ensure the safe and reliable operation of photovoltaic power generation systems and distribution networks.
1.0.2 This specification is applicable to the design, construction, and expansion of photovoltaic power generation system access distribution networks through a 380V voltage level access network and a 10kV (6kV) voltage level access to the user-side power grid.
1.0.3 Photovoltaic power generation access distribution network design should start from the overall situation and take into consideration the overall situation. According to the construction scale, project characteristics, development planning and distribution network conditions, the design scheme should be determined through technical and economic comparison.
1.0.4 In addition to the design of photovoltaic power generation distribution network, the design should comply with the relevant national standards.
2 Terms
2.0.1 point of interconnection (POI)
For a photovoltaic power generation system with a booster station, it refers to a booster station high-voltage-side bus or node. For a photovoltaic power generation system without a booster station, it refers to the output aggregation point of the photovoltaic power generation system.
2.0.2 Island islanding
Part of the power grid, which includes the load and power supply, continues to operate in isolation after being detached from the main network. Isolated islands can be divided into unplanned islands and planned islands.
2.0.3 unintended islanding
Unplanned and uncontrolled formation of islands.
2.0.4 planned islanding intentional islanding
According to the pre-configured control strategy, silos occur in a planned manner.
2.0.5 anti-islanding anti-islanding
Prevent the occurrence of unplanned island phenomenon.
2.0.6 T connection method "T" integration
A line is tapped from one line in the existing grid to access other users.
3 Basic regulations
3.0.1 When the photovoltaic power generation system adopts the T-connected mode, in the power flow calculation, power quality analysis and relay protection design, the impact of the different characteristics of the T-connection access and the special-line access on the distribution network should be analyzed.
3.0.2 In photovoltaic power generation access distribution network design, the power balance, power flow calculation and electrical parameter selection shall fully analyze the influence of the component type, tracking mode and irradiance on the photovoltaic power generation output characteristics.
3.0.3 Photovoltaic power access Distribution network design should use high efficiency, low energy consumption, high reliability and advanced performance electrical products.
3.0.4 Photovoltaic power generation systems that access through the 10kV voltage level may carry out special studies on the reactive power compensation and power quality of the photovoltaic power generation system connected to the distribution network when conducting the design of the access distribution network.
4 access system conditions
4.1 Status of Power System
4.1.1 The access system condition analysis shall include the analysis of the status of the power system and the development plan, and shall conduct a general analysis of the photovoltaic power generation system.
4.1.2 Design of the access system The current situation of the power system should be analyzed. The analysis should include the power supply, load and status of the power grid.
4.1.3 The current status of the power supply should include the installed capacity, power supply structure, power generation, and annual utilization hours.
4.1.4 Load Status Overview should include the maximum power load, power supply, load characteristics, and so on.
4.1.5 The current situation of the power grid should include the wiring mode of the power grid, the size of the substation surrounding the photovoltaic power generation system, the reserve and expansion conditions for the outgoing voltage interval of the relevant voltage class, the type and length of the line, and the condition of the line corridor.
4.2 Development Plan of Power System
4.2.1 The design of the access system should be based on local economic and social development plans and the historical power load growth situation, and forecast the load level and load characteristics of the distribution network in the relevant regional power grid and photovoltaic power generation system.
4.2.2 The design of the access system should outline the power supply development plan for the relevant regional power grid and the distribution network where the photovoltaic power generation system is located, including the new power supply construction schedule, unit decommissioning plan and power supply structure.
4.2.3 The design of the access system should outline the development plan of the distribution network of the relevant regional power grid and photovoltaic power generation system, including the layout and scale of the substation and the grid connection mode for the design year and the outlook year.
4.3 Overview of Photovoltaic Power Generation System
4.3.1 Overview of Photovoltaic Power Generation System The project should include the geographic location, environmental conditions, solar energy resources, planning scale, current construction scale, preliminary work progress, installation plan, design annual power generation, output characteristics, construction and production time, etc. .
4.3.2 For the expanded photovoltaic power generation system, an overview of the existing photovoltaic power generation system and the conditions for expansion should also be described.
5 partial design
5.1 General provisions
5.1.1 Partial design shall include the power balance, the necessity of construction and its role and role in the distribution network, voltage rating and access to the grid scheme, power flow calculation, calculation of short-circuit current, reactive power compensation, power quality, Technical and economic analysis of the program and electrical parameter requirements.
5.1.2 Part of the technical indicators shall meet the relevant provisions of the current national standard "Technical Regulations on PV Generation System Access Distribution Network" GB/T 29319.
5.2 Power Balance
5.2.1 In the calculation of power balance, according to the load characteristics and the output characteristics of the photovoltaic power generation system, the power balance tables of the distribution networks under typical load and photovoltaic power generation system zero output and maximum output are listed. The power balance for each horizontal year should be analyzed quarterly or monthly.
5.2.2 When the photovoltaic power generation system is large in scale, in addition to the provisions in Article 5.2.1 of this Code, the power balance sheet in each horizontal year of the distribution network shall also be listed.
5.3 The Necessity of Construction and Its Position and Role in Distribution Network
5.3.1 The necessity of photovoltaic power generation system construction should include meeting power demand, improving power supply layout and energy consumption structure, and promoting energy conservation and emission reduction.
5.3.2 According to the result of power balance, the power consumption range of photovoltaic power generation system should be analyzed, and the status and role of photovoltaic power generation system in the distribution network should be explained.
5.4 Voltage Level and Access to Grid Solutions
5.4.1 When carrying out the design of the access grid scheme, the connection mode and access conditions of the relevant voltage level grid before the current project of the photovoltaic power generation system is put into operation should be briefly described.
5.4.2 According to the scale of photovoltaic power generation system, status and role in the distribution network, access conditions and other factors, the voltage level of the access should be determined; it should be combined in the near future, the access network plan should be proposed, and the transmission line should be initially selected. Conductor section.
5.4.3 The necessary electrical calculations and technical and economic comparisons shall be made for the proposed access grid scheme, and a recommended scheme shall be proposed, including the access voltage level, outlet direction, number of outlet loops, and conductor cross-section.
5.4.4 When more than one PV system is connected to the same public connection point, the impact on the grid should be analyzed overall. When the total capacity of the photovoltaic power generation system exceeds 25% of the maximum load in the power supply area of ​​the upper-level transformer, special studies on reactive power compensation and power quality should be conducted.
5.4.5 When the ratio of the rated current of the photovoltaic power generation system to the three-phase short-circuit current at the grid connection point is higher than 10%, special studies on reactive power compensation and power quality should be conducted.
5.5 Power Flow Calculation
5.5.1 The load flow calculation shall include the typical maximum, minimum load operation mode, overhaul operation mode and accident operation mode of the design year. It should also calculate the operating mode of the main output period of the PV power plant's maximum output.
5.5.2 When the capacity of the photovoltaic power generation system is large, the line power and node voltage fluctuations caused by changes in the photovoltaic output under typical conditions should also be analyzed. The line power or node voltage limit should be avoided.
5.5.3 Load flow calculation The representative operating mode of the transition year and long-range year should be calculated.
5.5.4 It shall be verified by power flow calculation that the photovoltaic power generation system is connected to the power grid scheme, and the main parameters of the conductor cross-section and electrical equipment shall be selected.
5.6 Short Circuit Current Calculation
5.6.1 The calculation of short-circuit current shall include the three-phase short-circuit current of the photovoltaic system's grid connection point and nearby nodes in the current and long-term planned maximum operating modes.
5.6.2 The selection of electrical equipment should meet the requirements of short-circuit current calculation.
5.7 Reactive power compensation
5.7.1 The reactive power and voltage regulation capability of the photovoltaic power generation system shall meet the relevant provisions of the current national standard “Technical Regulations for PV Generation System Access Distribution Distribution Network†GB/T 29319. The reasonable and reactive power shall be selected through technical and economic comparison. Compensation measures include the capacity, type and installation location of reactive power compensation devices.
5.7.2 Calculation of reactive power compensation capacity of photovoltaic power generation system The factors such as power factor of the inverter, reactive power loss of the combined line, transformer and transmission line should be fully analyzed.
5.7.3 The power factor of the PV system shall be continuously adjustable within the range of 0.95 to 0.95. When it is necessary to install an auxiliary reactive power compensation device, an automatic reactive power compensation device should be used. If necessary, a dynamic reactive power compensation device should be installed.
5.7.4 Through the lOkV (6kV) voltage level grid connection, a photovoltaic power generation system with a unified step-up transformer can be equipped with a reactive power compensation device on the low-voltage side of the step-up transformer. When there is no unified step-up transformer, reactive power compensation devices that can be automatically adjusted can be dispersedly installed, and reactive power compensation devices can also be centrally configured at the grid connection point.
5.8 Power Quality
5.8.1 Photovoltaic power generation systems provide the local alternating current load with the energy and the quality of the power delivered to the grid. The current national standard “Power Quality Public Utility Grid†shall be satisfied in terms of harmonics, voltage deviation, three-phase voltage imbalance, voltage fluctuation and flicker. Harmonics" GB/T 14549, "Harmonics between utility power and utility grid" GB/T 24337, "Power supply voltage deviation," GB/T 12325, "Power quality three-phase voltage imbalance" GB/T 15543, "Energy Quality Voltage Fluctuations and Flicker" related provisions of GB/T 12326.
5.8.2 The direct current component of the photovoltaic power generation system injected into the public connection point shall not exceed 0.5% of its AC rated value.
5.8.3 Photovoltaic power system The power quality on-line monitoring device installed at the public connection point shall comply with the relevant provisions of the current national standard "general requirements for power quality monitoring equipment" GB/T 19862.
5.9 Program Technical and Economic Analysis
5.9.1 Technical and Economic Analysis of the Plan The investment estimation plan for each access system should be briefly listed, including part of the investment for the transmission line and the investment for the substation system substation. For part of the investment in the boosting station of the photovoltaic power generation system involved in each access system scheme, when the investment in the booster stations in each scheme is quite different, the investment analysis and comparison can be made in different sections of the investment estimation table.
5.9.2 The technical and economic analysis of the plan shall list the technical and economical comprehensive comparison tables of the various access system solutions, including the directions of consumption of the various access systems, the near-and-long-term adaptability of the plans, the distribution of the program trend, and the impact of the plan on the system operation (eg, Short-circuit current, power quality, etc.), investment estimates, etc.
5.9.3 Comprehensive technical and economic analysis and comparison shall be made to each access system scheme, and a recommendation scheme shall be proposed.
5.10 Electrical parameter requirements
5.10.1 The main electrical connection mode of the step-up station or output summary point of the photovoltaic power generation system shall be based on the planned capacity of the photovoltaic power generation system, the phases of construction, the power supply range, the near-field load conditions, the access voltage level, and the number of outlet loops. Determined by technical and economic analysis.
5.10.2 Parameters of electrical equipment for photovoltaic power stations shall comply with the following provisions:
1 The parameters of the main transformer shall include the number of units, rated voltage, capacity, impedance, voltage regulation method, voltage regulation range, connection group, taps, and neutral point grounding method when reacting to ground, and shall comply with the current national standard "power transformers". Selection guide GB/T 17468, "Technical parameters and requirements for oil-immersed power transformer" GB/T 6451, "Power transformer energy efficiency limit and energy efficiency rating" GB 24790 relevant provisions.
2 The performance requirements of reactive power compensation devices, as well as the power quality and reactive power adjustment capability of the inverter, shall meet the relevant requirements of the current national standard "Technical Regulations for Photovoltaic Power Generation System Access Distribution Network" GB/T 29319.
6 secondary design
6.1 General provisions
6.1.1 The secondary part design should include system relay protection, automatic control device, dispatch automation, electric energy metering device and electric energy remote terminal and communication system.
6.1.2 The secondary part of the technical indicators shall comply with the relevant provisions of the current national standard "Technical Regulations on Photovoltaic Power Generation System Access Distribution Network" GB/T 29319.
6.2 System Relay Protection
6.2.1 Special relay protection devices for photovoltaic power generation systems that are connected to the grid through 10kV (6kV) voltage levels shall comply with the relevant provisions of the current national standard "Technical Specifications for Relay Protection and Safety Automatic Devices" GB/T 14285. The photovoltaic power generation system connected to the power grid through the 380V voltage level should adopt fuses or circuit breakers, and no special relay protection device can be configured.
6.2.2 When the photovoltaic power generation system is connected to the distribution network, the existing protection of the adjacent lines of the transmission line of the photovoltaic power generation system shall be verified. If the requirements are not met, the protection shall be reconfigured.
6.2.3 When the access of the photovoltaic power generation system changes the single-sided power line in the distribution network to the two-sided power line, the protection should be configured on the double-sided power line.
6.2.4 Photovoltaic system busbars may not be provided with special busbar protection. When a fault occurs, the busbar active connection element can be used to cut off the fault.
6.3 Automatic Control Devices
6.3.1 Photovoltaic power generation systems shall be equipped with anti-islanding protection. At least one of active and passive anti-island protection shall be provided. When islands are detected, the connection to the distribution network should be disconnected. Anti-isolating protection should be matched with line protection. When reclosing lines, it should also cooperate with reclosing.
6.3.2 When the PV system is designed for irreversible grid connection, reverse power protection equipment should be configured. When it is detected that the reverse current exceeds 5% of the rated output, the photovoltaic power generation system should automatically reduce the output or stop sending power to the grid line within 2 s.
6.3.3 Photovoltaic power generation systems with planned island requirements should be equipped with frequency and voltage control devices. When abnormal voltage and frequency occur in isolated islands, the active and reactive power of photovoltaic power generation systems can be adjusted.
6.4 scheduling automation
6.4.1 The scheduling relationship of photovoltaic power generation system should be determined according to the conditions of the photovoltaic power generation system area, installation capacity and access distribution network voltage level.
6.4.2 The telecontrol equipment and scheduling data network equipment configuration plan of photovoltaic power generation system shall be determined according to the requirements of the dispatch automation system, the access voltage level of the photovoltaic power generation system and the distribution network access method.
6.4.3 Photovoltaic power generation systems connected with 10kV (6kV) voltage levels shall be required to provide remote information acquisition according to the requirements of the dispatch automation system, the voltage rating of the PV power generation system and the connection method. The telecontrol information should include grid connection status, PV system operation information (including active, reactive, and current, etc.), inverter status information, reactive power compensation device information, frequency and voltage information of the grid point, and boost station flow information. Relay protection and automatic device action information.
6.4.4 Communication between telecontrol system and dispatcher should clarify communication protocol, communication rate or bandwidth according to the requirements of dispatch automation system and communication transmission network conditions, and should comply with the current industry standard "Power System Dispatch Automation Design Technical Specification" DL/T 5003 Relevant regulations.
6.4.5 The photovoltaic power generation system connected to the grid with 10kV (6kV) voltage level shall be equipped with secondary system safety protection equipment according to the overall requirements for secondary safety protection of the power system.
6.5 Electric Energy Metering Device and Electric Energy Remote Terminal
6.5.1 The photovoltaic power generation system shall be equipped with an electric energy metering system, and shall determine the transmission scheme of the electric energy metering information according to the conditions of the data network and the channels. The electric energy metering system includes a metering gate table and electric energy remote terminal equipment.
6.5.2 Photovoltaic power system The energy metering device shall comply with the relevant provisions of the current industry standard "Technical Specification for Design of Electrical Energy Metering System" DL/T 5202.
6.5.3 The selection and configuration of energy metering devices shall comply with the following provisions:
1 The electric energy metering device shall have two-way active power and four-quadrant reactive power metering functions.
2 The same grid meter shall be configured for the on-grid power off point of the photovoltaic power generation system connected to the power grid through the 10kV (6kV) voltage level, and the two meters shall be operated in the primary/secondary mode.
3 The technical performance of the gateway table shall comply with the relevant provisions of the current industry standards "Multi-function Energy Meter" DL/T 614 and "Multi-function Energy Meter Communication Protocol" DL/T 645.
6.5.4 The accuracy level of the power meter and the transformer shall meet the following requirements:
1 The power meter accuracy level at the gateway metering point should not be lower than 0.5 s for active power and 2.0 for reactive power.
2 The accuracy level of voltage transformer should be 0.2 grade, and the accuracy level of current transformer should not be lower than 0.5S grade.
3 The technical performance of the gateway table shall comply with the relevant provisions of the current industry standards "Multi-function Energy Meter" DL/T 614 and "Multi-function Energy Meter Communication Protocol" DL/T 645.
6.5.5 Photovoltaic power generation system should be equipped with remote terminals for collecting electric energy, and the remote terminal shall comply with the relevant regulations of the current industry standard “Technical Specification for Design of Electric Energy Metering System†DL/T 5202-2004 Section 7.2 Electric Energy Remote Terminal.
6.6 Communication System
6.6.1 The construction plan of the communication system for the photovoltaic power generation system connected to the distribution network shall be determined according to the scheduling relationship, location, installation capacity, voltage level of the distribution network and the status of the relevant communication network of the photovoltaic power generation system.
6.6.2 Photovoltaic power generation systems with 10kV (6kV) voltage grid connection shall have a reliable dispatch communication channel from the PV generation system to the dispatcher.
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