Photovoltaic power station access power system design specification (GB/T 50866-2013)

1 General

1.0.1 This standard is formulated to regulate the design of photovoltaic power station access power systems and ensure the safe and stable operation of photovoltaic power stations and power systems.

1.0.2 This specification applies to the design, construction, and installation of photovoltaic power station access power systems that are connected to the public power grid through a voltage level of 35kV (2OkV) or higher and connected to the public power grid through a voltage level of 10kV (6kV).

1.0.3 The design of the photovoltaic power station access system should proceed from the overall situation and take all factors into consideration. The design scheme should be reasonably determined according to the construction scale, project characteristics, development planning and power system conditions.

1.0.4 In addition to the design of photovoltaic power station access systems, the design should comply with the relevant national standards.

2 Terms

2.0.1 point of interconnection (POI)

For a photovoltaic power station with a booster station, it refers to the booster station high-voltage bus or node.

For a photovoltaic power station without a booster station, it refers to the output summary point of the photovoltaic power station.

2.0.2 Low voltage ride through (LVRT)

When a power system accident or disturbance causes the voltage at the photovoltaic power station's grid connection point to fall, the photovoltaic power station can guarantee the ability to not run off the grid continuously during a certain voltage drop range and time interval.

2.0.3 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.

2.0.4 unintended islanding

Unplanned and uncontrolled formation of islands.

2.0.5 planned islanding intentional islanding

According to the pre-configured control strategy, silos occur in a planned manner.

2.0.6 Anti-islanding

Prevent the occurrence of unplanned island phenomenon.

2.0.7 T-connection T integration

A line is tapped from one line in the existing grid to access other users.

3 Basic regulations

3.0.1 Photovoltaic power station access system design. When performing power balance, flow calculation and electrical parameter selection, the impact of component type, tracking method, and output characteristics of photovoltaic power station should be fully analyzed.

3.0.2 During the design of the access system, special studies on the stability, reactive voltage and power quality of the photovoltaic power station access system can be conducted at the same time as required.

3.0.3 Photovoltaic power stations adopt the T-connection method. When carrying out power flow calculation, power quality analysis and relay protection design, the influence of the different characteristics of the T-connection mode and the special line receiver on the power system should be fully analyzed.

3.0.4 Photovoltaic power station access system design should use high efficiency, low energy consumption, high reliability and advanced performance electrical products.

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 deal with the general analysis of the photovoltaic power station.

4.1.2 The design of the access system should analyze the status of the power system. 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 scale and power supply structure, power generation, annual utilization hours, and peak shaving and frequency modulation characteristics.

4.1.4 The load status shall include the maximum load, the electricity consumption of the entire society, and the load characteristics.

4.1.5 The status of the power grid should include the connection mode of the power grid, the transmission and reception of power to and from the surrounding power grid, the size of the substation around the photovoltaic power station site, and the reserve interval of the relevant voltage class, as well as the extension conditions, the type and length of the circuit, and the corridor conditions. Wait.

4.2 Development Plan of Power System

4.2.1 The design of the access system should be based on the national economic and social development plan and the historical power load growth situation, and forecast the load level and load characteristics of the relevant power grid.

4.2.2 The design of the access system shall outline the power supply development plan of the relevant power grid. The power development plan shall include the distribution and characteristics of the power resources, the progress of the new power supply construction, the unit decommissioning plan and the power supply structure.

4.2.3 The design of the access system should outline the development plan of the relevant power grid. The development plan of the power grid should include the layout of the substation and the scale of the design year and the outlook year, the wiring mode of the power grid, and the power flow direction.

4.3 Photovoltaic Power Station Overview

4.3.1 Photovoltaic power station overview should include the geographic location of the project, environmental conditions, solar energy resources, planning, scale of the current period, the preparatory work, installation plan, design annual power generation, output characteristics, construction and production time, etc. content.

4.3.2 For the expansion of photovoltaic power stations, in addition to complying with the requirements of Article 4.3.1 of this code, the existing PV power plant overview, expansion conditions, etc. shall 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 the status and role of the photovoltaic generation station in the system, voltage level and access to the grid scheme, load flow calculation safety and stability analysis, short-circuit current calculation, reactive power compensation, Power quality, technical and economic analysis of the program, and electrical parameter requirements.

5.1.2 Partial technical indicators shall meet the relevant provisions of the current national standard “Technical Regulations for Photovoltaic Power Plant Access to Power Systems” GB/T 19964.

5.2 Power Balance

5.2.1 In the calculation of power balance, according to the characteristics of the load and the output characteristics of the photovoltaic power station, the power balance table of the grid under the maximum load of each level and the zero output of the photovoltaic power station and the maximum output mode shall be listed. The power balance for each horizontal year should be analyzed quarterly or monthly.

5.2.2 When calculating the balance of electric power, the balance of electric energy for each level of the relevant grid should be listed.

5.2.3 The power balance calculation shall analyze the system's peaking and frequency adjustment capabilities, and shall determine that the power grid can accept the power of the photovoltaic power station.

5.3 The Necessity of Construction and Its Position and Role in the System

5.3.1 The necessity of photovoltaic power plant construction should be discussed from the aspects of meeting power demand, improving power supply layout and energy consumption structure, promoting optimal allocation of resources, and energy conservation and emission reduction.

5.3.2 According to the results of power balance, the power consumption range and power transmission direction of photovoltaic power stations should be analyzed, and the status and role of photovoltaic power generation stations in the system should be explained.

5.3.3 The planning capacity, current construction scale, installation plan, construction and commissioning time of PV power stations shall be analyzed from the perspective of the power system and suggestions for rationalization shall be provided.

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 class grid before the photovoltaic power plant is put into production should be briefly described.

5.4.2 The photovoltaic power station voltage level shall be determined according to factors such as construction scale, status and role in the power system, access conditions, etc., and the necessary electrical calculations and technical and economic comparisons shall be made for the proposed access system solution. Suggest a proposal. The recommended scheme shall include the access voltage level, outlet direction, number of outlet circuits, and wire cross section.

5.5 Power Flow Calculation

5.5.1 The load flow calculation shall include the normal maximum, minimum load operation mode, maintenance operation mode, and accident operation mode that are representative of the design year, and the operation mode of the maximum output power of the photovoltaic power station shall be calculated.

5.5.2 Power flow calculations The line power and node voltage fluctuations caused by variations in PV output under typical conditions should be analyzed, and line power or node voltage crossings 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 Through the power flow calculation, the photovoltaic power station shall be inspected and connected to the power grid scheme. The main parameters of the conductor cross-section and electrical equipment shall be selected, and the voltage regulator device, reactive power compensation device and its configuration shall be selected.

5.6 Calculation and Analysis

5.6.1 For photovoltaic power stations connected to the grid through voltage ratings of 35kV and above, stability analysis shall be conducted to check whether the access of the PV power station satisfies the requirements for stable operation of the power system and whether measures to improve stability are required.

5.6.2 Stability Analysis Transient stability calculations should be performed. If necessary, static and dynamic stability calculations should be performed.

5.6.3 The normal operation mode adopted for the stabilization calculation shall be the operation mode where the power grid is normal but the PV power plant exerts the maximum output.

5.6.4 The type of fault used in the transient stability calculation shall comply with the relevant provisions of the current industry standard "Safety and Stability Guidelines for Power Systems" DL 755. The transient stability calculation shall also calculate the stability of the photovoltaic power plant under sudden change of output.

5.6.5 The photovoltaic power station model in the stable calculation should fully reflect its transient response characteristics.

5.6.6 When there is a stability problem in the photovoltaic power station receiver, a special study of the safety automation device should be carried out and a solution to the stability problem should be proposed.

5.7 Short-circuit current calculation

5.7.1 The calculation of short-circuit current shall include the three-phase and single-phase short-circuit currents of the PV grid connection point, the nearby node's current phase and the longest-planned year maximum operation mode.

5.7.2 The selection of electrical equipment should meet the requirements of short-circuit current calculation.

5.8 Reactive power compensation

5.8.1 The reactive power and voltage regulation capability of photovoltaic power stations shall meet the relevant provisions of the current national standard "Technical Regulations for Photovoltaic Power Plant Access to Power Systems" GB/T 19964. The technical and economical comparison shall be used to select reasonable reactive compensation measures, including the capacity, type, control method and installation position of the reactive power compensation device.

5.8.2 The calculation of reactive power compensation capacity of photovoltaic power stations shall fully analyze the reactive power regulation capability of the inverter and factors such as reactive power loss and charging power of the aggregated lines, transformers and transmission lines.

5.8.3 Photovoltaic power stations shall be equipped with reactive power control systems or automatic voltage control systems and shall make full use of the reactive power adjustment capability of the photovoltaic inverters. When the reactive capacity of the inverter cannot meet the requirements of system reactive power or voltage regulation, a reactive power compensation device with appropriate capacity shall be installed in the photovoltaic power station, and a dynamic reactive power compensation device shall be installed when necessary.

5.9 Power Quality

5.9.1 The quality of photovoltaic power stations sending electrical energy to the grid shall meet the current national standard "Power Quality Harmonics of Public Power Grid" in terms of harmonics, voltage deviation, three-phase voltage imbalance, voltage fluctuations and flicker, etc. GB/T 14549 , "Power Quality Harmonics Between Utility Grids" GB/T 24337, "Power Quality Supply Voltage Deviation" GB/T 12325, "Energy

Quality three-phase voltage imbalance "GB/T 15543, "Power Quality Voltage Fluctuation and Flicker" GB/T 12326 relevant provisions.

5.9.2 Photovoltaic power stations shall be equipped with real-time on-line power quality monitoring devices at the grid connection point. The installed power quality monitoring devices shall meet the relevant provisions of the current national standard "general requirements for power quality monitoring equipment" GB/T 19862.

5.10 Program Technical and Economic Analysis

5.10.1 The technical and economic analysis of the plan shall list the investment estimation plans of the access systems. The investment estimation table shall mainly include the investment of the transmission line, the investment in the substation system substation, and the investment of the dispatching terminating person. When there is a large difference in the investment of the booster stations of the various access systems,

The juxtaposition of the differences should be made and a comparative investment analysis should be conducted.

5.10.2 The technical and economic analysis of the plan shall list the technical and economical comprehensive comparison tables of the various access systems, which mainly include the direction of consumption, the near-and-long-term adaptability of the plan, the distribution of the program's tidal current, etc., as well as the investment estimates.

5.10.3 Technical and Economic Analysis of the Scheme The comprehensive technical and economic analysis and comparison of the various schemes of the access system shall be conducted, and a recommended scheme shall be proposed.

5.11 Electrical parameter requirements

5.11.1 The main electrical connection mode of the boost station or output summary point of the photovoltaic power station shall be based on the planned capacity of the photovoltaic power station, the phased construction condition, the power supply scope, the near area load condition, the access voltage level and the number of outlet circuit and other conditions. Determined by technical and economic analysis.

5.11.2 Parameters of electrical equipment for photovoltaic power stations shall meet the following requirements:

1 The parameters of the main transformer should include the number of units, rated voltage, capacity, impedance, voltage regulation mode (with or without excitation), voltage regulation range, connection group, taps and neutral grounding methods, and should comply with the current national standards. "Guidelines for the Selection of Power Transformers" GB/T 17468, "Technical Parameters and Requirements for Oil-Filled Power Transformers" GB/T 6451, "Restrictions on Energy Efficiency of Energy Transformers and Energy Efficiency Rating" GB 24790.

2 The performance of reactive power compensation devices, as well as the power quality, reactive power regulation capability, and low-voltage ride-through capability of inverters, shall comply with the relevant provisions of the current national standard "Technical Regulations for Photovoltaic Power Stations Receiving Power Systems" GB/T 19964.

6 secondary design

6.1 General requirements

6.1.1 The design of the secondary part shall include the design of system relay protection, automatic control device, power system automation, electric energy metering device and electric energy remote terminal and communication system.

6.1.2 The technical indexes of the secondary part shall meet the relevant provisions of the current national standard "Technical Regulations for Photovoltaic Power Stations Receiving Power System" GB/T 19964.

6.2 System Relay Protection

6.2.1 Photovoltaic power stations shall be equipped with special relay protection devices in accordance with the relevant requirements of the current national standard "Technical specifications for relay protection and safety automatic devices" GB/T 14285.

6.2.2 The dedicated transmission lines for photovoltaic power stations shall be protected by the configuration of the power lines on both sides.

6.2.3 When the PV power station sending line is T-connected, the circuit protection station of the PV power station should be equipped with line protection devices.

6.2.4 Existing protection of PV transmission lines adjacent to the line should be verified. When the requirements are not met, the protection should be reconfigured.

6.3 Automatic Control Devices

6.3.1 The retransmission shall be configured for the transmission lines of photovoltaic power stations. After the fault is cut off, the power grid side shall implement no-pressure overlap detection, and the photovoltaic power generation station side shall implement the coincidence period.

6.3.2 Photovoltaic power stations should be equipped with independent anti-islanding protection. Anti-islanding protection should be compatible with line protection, reclosing and low voltage ride-through capabilities.

6.3.3 Photovoltaic power plants with planned island requirements should be equipped with frequency and voltage control devices. When frequency or voltage abnormalities occur in isolated islands, active and reactive power of photovoltaic power stations can be adjusted.

6.4 Power System Automation

6.4.1 The scheduling relationship of photovoltaic power stations shall be determined according to the conditions of the photovoltaic power station's location, installation capacity and access voltage level.

6.4.2 Photovoltaic power plants should be able to participate in automatic voltage control (AVC). Photovoltaic power plants with a total capacity of 10MW and above should be able to participate in automatic power generation control (AGO).

6.4.3 The configuration scheme of telecontrol equipment and dispatch data network equipment for photovoltaic power stations shall be determined according to the requirements of the dispatch automation system, the access voltage level of the photovoltaic power station and the mode of access.

6.4.4 The scope of remote information acquisition shall be determined according to the requirements of the dispatch automation system, the voltage rating of the photovoltaic power station, and the connection method. Teleoperation information should include grid connection status, resource and environmental data (irradiance, ambient temperature, etc.), photovoltaic power station operating information (active, reactive, current, etc.), inverter status information, and reactive power compensation device information. Grid point frequency and voltage information, boost station flow information, relay protection and automatic device action information, power prediction curve.

6.4.5 Communication between the telecontrol system and the dispatcher shall be based on the requirements of the dispatch automation system and the conditions of the communications transmission network. The communications protocol, communication rate or bandwidth shall be clearly defined and shall comply with the current industry standard "Power System Dispatch Automation Design Specification" DL/ T 5003 related regulations.

6.4.6 The synchronized phasor measurement device shall be installed in photovoltaic power stations that are connected to 220kV and above voltage classes.

6.4.7 According to the overall requirements of the secondary security protection of the power system, secondary system security protection device configuration should be carried out.

6.5 Electric energy metering device and power f remote terminal

6.5.1 The photovoltaic power station 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 channel. The electric energy metering system shall include the metering gate table and the electric energy remote terminal equipment.

6.5.2 Photovoltaic power plant electric energy metering devices shall comply with the relevant provisions of the current industry standard "Electric Energy Metering System Design Technical Regulations" DL/T 5202.

6.5.3 The selection and configuration of the energy metering device shall meet the following requirements:

1 The electric energy metering device shall have two-way active power and four-quadrant reactive power metering functions.

2 The grid power off point of the photovoltaic power station should be configured with the same two meters and should be operated in the main/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 shall be 0.2 s of active power and 2.0 of reactive power.

2 The accuracy level of the voltage transformer should be 0.2, and the accuracy level of the current transformer should be 0.2S.

3 The requirements of the accuracy class in Section 5.3 of DL/T 448-2000 of the current industry standard “Technical Management Regulations for Electric Energy Metering Devices” should be met.

6.5.5 Photovoltaic power stations shall be equipped with remote terminals for collecting electric energy. The remote terminals shall comply with the relevant provisions of the current industry standard “Technical Specification for Design of Electric Energy Metering Systems” DL/T 5202-2004 Section 7.2 Electric Energy Remote Terminals.

6.6 Communication System

6.6.1 The system communication shall meet the requirements for transmission channels of photovoltaic power station dispatch automation system, relay protection, automatic control device signals and dispatch, and production exchange voice system.

6.6.2 The construction plan of the communication system for photovoltaic power station access should be determined according to the dispatching organization, location, installation capacity, access voltage level, and the status of the relevant communication network of the photovoltaic power station.

6.6.3 The communication capacity of the communication system shall be determined according to the statistics of the amount of information from the photovoltaic power station to the dispatcher.

6.6.4 The photovoltaic power station shall have at least one reliable dispatch communication channel to the dispatcher.

6.6.5 Photovoltaic power stations connected to the grid through 110kV (66kV) and above voltage levels to the dispatcher shall have two communication channels, one of which shall be a cable channel.

6.6.6 Photovoltaic power stations shall propose a networking scheme according to the networking mode of the dispatching and production switching network in their area, and shall propose scheduling and production-controlled switch capacity according to the installed capacity of photovoltaic power stations.

6.6.7 Photovoltaic power station communication and secondary power system should adopt integrated design, integrated configuration and integrated monitoring.