CN100511900C - DC power guiding transmission deicing operation method - Google Patents

Abstract

The invention relates to a dedicated operation mode for ice melting for bipolar power anisotropic transmission in a direct current transmission system. In this mode of operation, one pole of the DC system transmits power in the forward direction and the other pole transmits power in the reverse direction. Both poles can run a large power to form a power circulation; the DC lines of the two poles can generate a large DC current, thereby generating enough heat to meet the ice melting requirements. Since the bipolar power is transmitted in opposite directions, after the power of the two poles cancels out a part of each other, the actual power transmitted between the two stations is still small, which is suitable for the case of low load in the dry season. It can meet the ice-melting requirements of DC lines under low-load conditions in dry seasons, and solve the problem of icing on DC lines under low-load conditions in dry seasons in winter.

Description

DC power anisotropic transmission and ice melting operation mode

technical field

The present invention relates to a special ice-melting operation mode for the bipolar power anisotropic transmission of the high-voltage direct current transmission system. More specifically, the method is used for the operation mode of the direct current transmission system of any voltage level for the DC line melting ice in the dry season, and utilizes direct current transmission The first pole of the system transmits the power from the rectifier side to the inverter side, and then uses the second pole to transmit the power from the inverter side back to the rectifier side, so that the power transmission between the rectifier side and the inverter side AC network is completed without power transmission The DC line runs with electricity, and melts the ice of the DC line through the heat generated by the DC current on the DC line.

Background technique

China is one of the countries with the most severe icing on transmission lines in the world. Severe icing will lead to a sharp decline in the mechanical and electrical performance of transmission lines, resulting in icing accidents. There have been icing accidents on transmission lines in Hunan, Hubei, Guizhou, Jiangxi, Yunnan, Sichuan, Henan and Shaanxi provinces. Icing accidents have seriously threatened the safe operation of my country's power system and caused huge economic losses.

Since the beginning of winter in 2008, some areas of our country have experienced heavy snowstorms that have not happened in decades. In the areas of Huanghuai, Jianghuai, and northern Jiangnan, the strong cold air has caught up with the southward movement, the temperature is relatively low, and the water vapor conditions are relatively good. There was a big snowstorm. The continuous rain, snow and freezing weather make the power supply situation extremely severe. Due to large areas of ice covering transmission lines and towers, power transmission and transformation facilities in some areas have been damaged one after another, and related power plant generators have also tripped and shut down.

From a historical point of view, since the 1950s, according to incomplete statistics, there have been thousands of large and small icing accidents on power transmission lines in my country. In 2003 alone, there were 79 trips of 110-500kV transmission lines due to icing, accounting for 3.27% of the total accidents, of which 13 were 500kV line trips; 47 unplanned outages of 110-500kV lines were caused by icing, accounting for 3.27% of the total accidents 4.24% of accidents. From December 2004 to February 2005, a large-scale ice disaster occurred in my country's central China power grid. In Hunan Province alone, more than 7 million people were affected, and the direct economic loss exceeded 1 billion yuan.

In order to solve the problem of line icing under ice and snow weather in winter, there are many solutions. Judging from the current situation, the main means of anti-icing and emergency rescue of power grid lines is still the traditional manual tower deicing. This method is not only dangerous, but also inefficient, and it is a last resort to remedial measures. In order to fundamentally improve the anti-icing ability of the transmission line, it is necessary to start from the design and technology. Since the DC transmission system is a highly controllable system, without changing the main circuit design and main wiring of the DC system, make full use of It will be the most economical solution to change the operation mode of the original DC lines and other primary equipment to melt the ice and ensure the safe and stable operation of AC and DC transmission lines under extreme weather conditions.

The present invention proposes a DC operation mode for melting the ice of the DC line based on the current DC transmission system in winter when the DC line is covered with ice. This method does not require any modification of the primary equipment, and only needs to modify the existing DC transmission The control and protection of the system can be realized by modifying the software of the system.

Contents of the invention

The purpose of the present invention is to propose a deicing operation mode of the direct current transmission system, which does not need to modify or upgrade the primary equipment, but only needs to modify the software of the secondary system. In the case of low load in the dry season, this ice-melting operation mode is more suitable. The first pole of the DC transmission system is used to transmit the power from the rectifier side to the inverter side, and then the second pole is used to transmit the power from the inverter side back to the rectifier side, thus The live operation of the DC line is completed without power transmission between the AC network on the rectifier side and the inverter side, and the DC line is melted by the heat generated by the DC current on the DC line.

Description of drawings

Figure 1 is a schematic diagram of the power flow direction of the DC system when the DC power anisotropic transmission is used for ice-melting operation.

Detailed ways

In the mode of ice-melting DC power anisotropic transmission, as shown in Figure 1, the first pole of the sending system adopts rectification operation, and the first pole of the receiving system adopts inverter operation. For the sending and receiving system, the DC power is At the same time, the second pole of the receiving end system adopts rectification operation, and the second pole of the sending end system adopts inverter operation. For the sending and receiving end system, the DC power is transmitted from the receiving end to the The sending end is for reverse power transmission. In the above-mentioned operation mode, both the first pole and the second pole can operate relatively large power to form a power circulation; the direct current lines of the two poles can both generate relatively large direct current. Since the power of pole 1 and pole 2 on both sides is transmitted in opposite directions, after the power of the two poles cancels out a part of each other, the actual power transmitted between the sending end system and the receiving end system is very small, which can meet the requirements of the small load of the DC line in the dry season requirements, and at the same time meet the ice melting requirements of the DC line.

For the currently operating DC transmission system, in order to use this method to realize the function of ice-melting operation, it is necessary to modify the relevant control and protection functions in the software of the secondary system, and special design and research and development are required. The aspects involved are mainly include:

1. DC sequence control function

2. DC power current control function

3. DC system reactive power control function

4. Converter transformer tap control function

5. DC line traveling wave protection

6. Modification of operator control system interface

After modifying the corresponding control and protection software, adopting the ice-melting operation mode of the present invention will be the most economical solution for the line ice-melting of the direct current transmission system that has been put into operation.

Claims (2)

1, a kind of HVDC (High Voltage Direct Current) transmission system ice melting operation method, it is characterized in that: a utmost point forward power of an end of HVDC (High Voltage Direct Current) transmission system, another utmost point reverse transfer power of this end, form power circulation, all can produce the direct current that satisfies the ice-melt heat in two DC line that the utmost point connected.

2, HVDC (High Voltage Direct Current) transmission system ice melting operation method as claimed in claim 1, it is characterized in that: there are not Power Exchange substantially in sending end AC system that is connected with DC transmission system and receiving end AC system.

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