CN106130073A - A kind of selection method based on distributed photovoltaic low pressure anti-islanding device - Google Patents

Abstract

The invention discloses a line selection method based on a distributed photovoltaic low-voltage anti-islanding device, which connects three low-voltage anti-islanding device dedicated circuit breakers for three low-voltage anti-islanding devices to be protected in one-to-one correspondence; The special circuit breakers for low-voltage anti-islanding devices are all connected to a line selection universal switch, and the line selection universal switch is connected to a switching universal switch; the switching universal switch is connected to a disturbance load; During power outage inspection and maintenance of photovoltaic power distribution lines, manually rotate the line selection universal switch in the island line selection module, select the line to be disturbed by selecting the circuit breaker, and then rotate the switching universal switch in the island line selection module, through the control The circuit breaker is closed and the disturbance load is switched on, which reduces the line voltage and forces the inverter to disconnect the unplanned island. The method can realize islanding protection for three lines by one distributed photovoltaic low-voltage anti-islanding device, which greatly saves device configuration costs and reduces the workload of operation and maintenance personnel.

Description

A line selection method based on distributed photovoltaic low-voltage anti-islanding device

technical field

The invention relates to the field of photovoltaic power generation systems.

Background technique

The island effect means that when the power grid loses voltage, the output of distributed photovoltaic power sources connected to the grid on the user side is balanced with the load nearby, and the system still maintains the state of continuing to supply power to a certain part of the power grid. When electric power maintenance personnel are maintaining lines or equipment related to distributed photovoltaic power generation, once the anti-islanding protection function of distributed photovoltaic power generation fails, it will bring hidden dangers to the on-site safety work of electric power maintenance personnel.

In the distributed photovoltaic power generation system, the islanding detection method at the grid side and the anti-islanding effect protection scheme based on the inverter were used in the past. Beginning in 2013, low-voltage anti-islanding devices dedicated to distributed photovoltaics were used. Dedicated anti-islanding equipment, consisting of an operating switch and a disturbance load. When the distributed photovoltaic power generation system operates in an unplanned island, by changing the power balance of the distributed photovoltaic power generation island system, the unplanned island operation is destroyed to protect the safety of system equipment and related personnel.

Although the existing low-voltage anti-islanding devices can effectively destroy unplanned islanding operations and protect the safety of transport and inspection personnel, they are all designed with a single line. Closing the switch of the low-voltage anti-islanding device will immediately reduce the voltage of all branches under the bus, and the affected area will be large. Especially for branch circuits without distributed power supply, or branch circuits without island effect, it is urgent to develop a low-voltage anti-islanding device with line selection function to reduce adverse effects.

Contents of the invention

The purpose of the present invention is to provide a line selection method based on a distributed photovoltaic low-voltage anti-islanding device, which can set a low-voltage anti-islanding device that can select lines for circuits containing distributed power supply branches.

In order to realize the above-mentioned purpose of the invention, the present invention can adopt following technical scheme:

A line selection method based on a distributed photovoltaic low-voltage anti-islanding device, which is characterized in that three special circuit breakers for low-voltage anti-islanding devices are provided, and the three low-voltage lines containing distributed photovoltaics to be protected are connected to three Special circuit breaker for low-voltage anti-islanding device; the three special circuit breakers for low-voltage anti-islanding device are all connected to a universal switch for line selection, and the universal switch for line selection can only be connected to one special circuit breaker for low-voltage anti-islanding device at the same time; The line universal transfer switch is connected to a switching universal transfer switch; the switching universal transfer switch is connected to a disturbance load, and the switching universal transfer switch controls the switching of the disturbance load; During operation, connect one of the lines to be disturbed connected to the special circuit breaker of the low-voltage anti-islanding device through the line selection universal switch, and control the special circuit breaker of the low-voltage anti-islanding device to close by switching the universal switch, so as to reduce the disturbance load. Line voltage, forcing the inverter to disconnect from unintended islands.

The beneficial effects of the present invention are:

After adopting the above technical scheme, when the distribution transformer bus is powered off for maintenance, the present invention can perform selective island protection operation on the three distributed photovoltaic branch circuits connected under the bus, and pull down the line resistance by disturbing the load, forcing the photovoltaic parallelism Grid inverter action, eliminate the islanding effect of the corresponding line, reduce the impact on the branch without distributed power supply, or the branch without islanding effect, complete the functional requirements of the original three low-voltage anti-islanding devices, greatly reduce On the basis of investment costs, reduce the adverse effects of island protection;

Moreover, this method can realize the island protection of three lines by one distributed photovoltaic low-voltage anti-islanding device, and the three lines are mutually blocked, which greatly saves the cost of device configuration and reduces the workload of operation and maintenance personnel.

Description of drawings

Fig. 1 is a schematic diagram of the principle of the present invention.

detailed description

Below in conjunction with accompanying drawing and specific embodiment, further illustrate the present invention, should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention, after having read the present invention, those skilled in the art will understand various aspects of the present invention Modifications in equivalent forms all fall within the scope defined by the appended claims of this application.

Please refer to FIG. 1 , the present invention discloses a line selection method based on a distributed photovoltaic low-voltage anti-islanding device. Among them, three special circuit breakers 1 for low-voltage anti-islanding devices are provided, and the three low-voltage lines containing distributed photovoltaics to be protected are connected to three special circuit breakers 1 for low-voltage anti-islanding devices one by one. The voltage of the low-voltage line mentioned above is 0.4kV. The three special circuit breakers 1 for low-voltage anti-islanding devices are all connected to a line selection universal transfer switch 2, and the line selection universal transfer switch 2 can only be connected to one special circuit breaker for low-voltage anti-islanding devices at the same time. The line selection universal changeover switch 2 is connected with a switching universal changeover switch 3 . The switching universal changeover switch 3 is connected with a disturbance load 4 , and the switching universal changeover switch 3 controls the switching of the disturbance load 4 . In this embodiment, the disturbance load 4 is a three-phase load, and three dedicated circuit breakers for low-voltage anti-islanding devices share a set of three-phase loads. When carrying out power outage maintenance work involving distributed photovoltaic power distribution lines, the line to be disturbed connected to one of the special circuit breakers for low-voltage anti-islanding devices is connected through the line selection universal switch, and the special circuit breaker for low-voltage anti-islanding devices is controlled by switching the universal switch. The circuit breaker is closed and the disturbance load is turned on, which reduces the line voltage and forces the inverter to disconnect the unintended island. The method can realize the anti-islanding protection of up to three lines. When the device using this method is connected to the busbar of the distribution transformer, it can perform selective islanding protection operations on the three branch circuits containing distributed photovoltaics under the busbar, reducing unnecessary The branch circuit with distributed power supply, or the branch circuit without islanding effect, realizes the function that can only be completed by the original three low-voltage anti-islanding devices, which greatly saves the cost of device configuration and reduces the workload of operation and maintenance personnel .

The above embodiment is only a description of the technical solution of the present invention, and the scope of protection of the present invention is not limited thereto. Any modification or equivalent replacement of the specific embodiments of the present invention by those familiar with the profession shall be included in the rights of the present invention. within the required range.

Claims (3)

1. A line selection method based on a distributed photovoltaic low-voltage anti-islanding device, which is characterized in that three special circuit breakers for low-voltage anti-islanding devices are provided, and the three low-voltage lines containing distributed photovoltaics to be protected are connected one by one Three special circuit breakers for low-voltage anti-islanding devices; the three special circuit breakers for low-voltage anti-islanding devices are all connected to a universal switch for line selection, and the universal switch for line selection can only be connected to one special circuit breaker for low-voltage anti-islanding devices at the same time; The line selection universal transfer switch is connected to a switching universal transfer switch; the switching universal transfer switch is connected to a disturbance load, and the switching universal transfer switch controls the switching of the disturbance load; During power outage maintenance work, connect one of the lines to be disturbed connected to one of the special circuit breakers for the low-voltage anti-islanding device through the line selection universal switch, and control the special circuit breaker for the low-voltage anti-islanding device to close by switching the universal switch to switch on the disturbance load. to reduce the line voltage, forcing the inverter to disconnect from unintended islands. 2. The line selection method based on distributed photovoltaic low-voltage anti-islanding device according to claim 1, characterized in that: the disturbance load is a three-phase load, and three dedicated circuit breakers for low-voltage anti-islanding devices share a group of three-phase loads . 3. The line selection method based on the distributed photovoltaic low-voltage anti-islanding device according to claim 2, characterized in that: the voltage of the low-voltage line is 0.4kV.