Photovoltaic and energy storage integrated monitoring and operation and maintenance solutions

Preface

Since the beginning of this year, driven by favorable policies, new energy industries such as photovoltaic, wind power, electrochemical energy storage and pumped storage have developed rapidly, and installed capacity has increased significantly. New energy power generation has become an important part of the new power system. At the same time, this also makes the new power system more complex than the traditional power system. In the future, it is expected that the scale of renewable energy installed capacity will continue to grow rapidly, gradually completing the deep transformation of the energy system and ultimately achieving the goal of "carbon neutrality". What follows is how to achieve efficient operation and maintenance management of photovoltaic power stations, energy storage and supporting electrical facilities through the system to make them operate safely, reliably and efficiently.

Keywords: photovoltaic monitoring; photovoltaic operation and maintenance; energy storage monitoring; energy storage operation and maintenance; box-type transformer monitoring

1. Development trends of photovoltaic and energy storage in 2023

According to data from the New Energy and Renewable Energy Department of the National Energy Administration, in the first quarter of 2023, the country's new photovoltaic grid-connected capacity reached 33.66GW, a year-on-year increase of 154.8%, including 15.53GW of centralized photovoltaic power generation and 18.13GW of distributed photovoltaic power generation. As of the end of the first quarter, the national photovoltaic power generation installed capacity reached 425GW, including 249GW of centralized photovoltaic power generation and 176GW of distributed photovoltaic power generation. Investment in solar power generation reached 52.2 billion yuan, a year-on-year increase of 177.6%. In the first quarter, the country's new wind power grid-connected capacity reached 10.40GW, including 9.89GW of onshore wind power and 0.51GW of offshore wind power. As of the end of the first quarter, the country's cumulative installed wind power capacity reached 376GW, a year-on-year increase of 11.8%, including 345GW of onshore wind power and 30.89GW of offshore wind power. Wind power investment reached about 24.9 billion yuan, a year-on-year increase of 15%.

From January to April 2023, there are 73 electrochemical energy storage projects in operation, with an installed capacity of 2.523GW/5.037GWh, and an installed power increase of 577.1% compared with the same period last year (374.4MW). Among them, there are 69 lithium iron phosphate energy storage projects with an installed capacity of 2.52GW/5.019GWh; there are 4 liquid flow battery energy storage projects with an installed capacity of 3.1MW/18.1MWh.

The installed capacity of photovoltaic power stations and electrochemical energy storage power stations both increased significantly in the first half of this year. It is expected that due to policy incentives, photovoltaic and energy storage systems will continue to grow significantly in the future to meet the requirements of the dual carbon plan.

1. Photovoltaic and energy storage operation and maintenance market analysis

As the photovoltaic and energy storage industries develop rapidly, there are also many biddings for monitoring, operation and maintenance management projects of built photovoltaic, wind power stations and energy storage systems. In the first half of 2023, the scale of operation and maintenance bidding of photovoltaic power station developers was 28.6GW, a year-on-year increase of 204.3%. Among the above 28.6GW bidding projects, 14.9GW have been announced as the winning bids. The winning bids are shown in Table 1. The price of photovoltaic operation and maintenance varies greatly due to the geographical distribution, capacity, environment and assessment conditions of photovoltaic power stations. It can be seen from Table 1 that the operation and maintenance price is as low as 1.93 yuan/year*kW.

Table 1. Tendering and winning of photovoltaic power station operation and maintenance

Similarly, the price of operation and maintenance of energy storage power stations fluctuates greatly. For example, Guangdong Power Grid Energy Investment Co., Ltd. issued a bidding announcement for the equipment and operation and maintenance of a 200MWh user-side energy storage project in 2023, with an operation and maintenance service price of 6 yuan/year*kWh; Karamay City’s 600MW photovoltaic supporting 120MW/240MWh energy storage operation and maintenance general contracting bid price is 499 yuan/year*kWh, and the operation and maintenance includes the operation and maintenance of photovoltaic equipment, energy storage equipment, and supporting electrical equipment such as box transformers.

The price of operation and maintenance of photovoltaic and energy storage systems is not high, and the assessment pressure is high. The operation and maintenance work is cumbersome, and there are safety risks if the management is improper. If a suitable monitoring system is not used for management and operation, the labor cost will be very high, and the power generation efficiency will be difficult to control, which will lead to the unprofitability of the operation and maintenance company. For a long time, the operation and maintenance management of new energy power stations was very "rough", in a word, it was a pile of people. The incompleteness of early power generation equipment, the many construction loopholes caused by the rush to start, the lack of scientific site selection, etc., all made the management of power stations inseparable from human support. But this process is not without changes. Through various technical means of upgrading, the operation and maintenance of new energy power stations has gradually changed from extensive management to lean management. Practitioners are also constantly exploring how to reduce dependence on manpower and how to improve management efficiency.

1. Distributed photovoltaic power station monitoring and centralized operation and maintenance management

The operation and maintenance of photovoltaic power stations is crucial to the power generation of photovoltaic power stations, including photovoltaic components, inverters and related electrical circuits, step-up transformers and grid-connected cabinets. Data monitoring is a very important part of the operation and maintenance of photovoltaic power stations. The various data indicators of photovoltaic power stations can be obtained in real time through the operation and maintenance management system, and the operation status and efficiency of the power station can be judged through these data indicators. In terms of data monitoring, the following tests need to be carried out on photovoltaic power stations: First, the voltage, current, power and other parameters of the power station need to be monitored in real time to understand the real-time working status of the photovoltaic power station. Secondly, the environmental factors such as temperature, humidity, solar irradiance of the photovoltaic power station need to be monitored to understand the operating environment of the power station. Finally, the cumulative power generation of the photovoltaic power station, the operation status of the components and inverters, etc. need to be tested and analyzed so as to take corresponding maintenance measures in time. GB/T 38946-2020 "Technical Specifications for Centralized Operation and Maintenance of Distributed Photovoltaic Power Generation Systems" makes clear requirements for the operation and maintenance of distributed photovoltaic power stations and the functions of centralized operation and maintenance master stations and operation and maintenance substations.

• 1. Related standards

Technical Specification for Centralized Operation and Maintenance of Distributed Photovoltaic Power Generation Systems GB/T 38946

"Technical Specification for Grid-connected Interface of Household Distributed Photovoltaic Generation" GB/T 33342

"Technical Specification for Remote Monitoring of Distributed Photovoltaic Power Generation Systems" GB/T 34932

"Design Specifications for Photovoltaic Power Stations" GB 50797

"Distributed Generation Grid-connected Operation Control Specification" GB/T 33592

Technical Regulations for Distributed Generation Access to the Grid Q/GDW1480

• 1. System Configuration

The centralized operation and maintenance system may include a master station and substations as well as communication channels between them. The system structure may refer to FIG1 .

a) The communication between the master station and the substation can be carried out by wireless (GPRS/3G/4G), public network, or private network (dedicated line/VPN encrypted link), and appropriate information security protection measures should be taken;

b) The communication between the master station and the external system meets the access requirements of the corresponding system;

c) Video information should not share the same channel with surveillance data transmission;

d) Support communication with the power grid dispatching system. The communication protocol should preferably adopt DL/T634.5101､DL/T634.5104; support communication with each substation.

Figure 1 Operation and maintenance master station and substation system architecture

The operation and maintenance substation can be set up according to the installed capacity of the distributed photovoltaic power station, whether there is on duty or not, etc. If there is no one on duty, the local operation and maintenance substation does not need to be set up, and the data is directly uploaded to the operation and maintenance main station through the data gateway.

• 1. Photovoltaic operation and maintenance substation solution

Acrel1000-DP distributed photovoltaic power station power monitoring system provides a solution for the operation and maintenance subsystem of distributed photovoltaic power stations, meeting the relevant technical requirements for operation and maintenance substations in GB/T 38946 "Technical Specifications for Centralized Operation and Maintenance of Distributed Photovoltaic Power Generation Systems".