This paper briefly introduces the line loss condition, analyzes the composition of the power system line loss, and puts forward the technical measures for the loss reduction and energy saving of the distribution system, and then cooperates with the management measures of the distribution system to reduce the loss and save energy.
1. Classification of line loss
1.1 according to the nature of loss
1.1.1 Technical line loss
In the process of power transmission and distribution of power grid, some losses are unavoidable. It is determined by the load condition of the power grid and the parameters of the power supply equipment at that time. It can be theoretically calculated that this part of normal and reasonable power consumption is called technical line loss. Also known as theoretical line loss. For the technical line loss, in terms of the actual situation, although the optimization of the power grid has greatly reduced the technical line loss, it is more difficult to reduce it on this basis, because this requires not only policy support. It also takes a lot of manpower and material resources. As far as the actual capacity of the power supply unit is concerned, a long-term strategic plan should be set up for the energy-saving and loss-reduction of the distribution network. For example, replacing high-energy-consuming transformers, shortening the power supply radius of the distribution network line, and increasing the cross-section of the wires.
1.1.2 Management Line Loss
In the operation process of electric power marketing, in order to accurately measure and count, it is necessary to install a number of measuring devices and meters such as transformers and electric energy meters, and these devices and meters have different degrees of error. At the same time, due to the quality relationship of the power-receiving personnel, there will be a phenomenon of missing copying, estimating and not reading according to the same period of time, coupled with poor management, insufficient implementation, partial leakage and a small amount of self-use and other Various losses caused by unknown factors. This type of loss is ultimately caused by poor management, so it is called management line loss. For managing line losses, this is an aspect that we can work hard to reduce and significantly reduce. Because the factors of production management line loss are mainly the different degrees of error of metering devices and meters, such as transformers and electric energy meters, and the quality of personnel who use electricity meter reading, such as missing copy, estimated copy, wrong copy and not reading according to regulations. . We proceed from the above aspects, standardize management, improve the rules and regulations, start from the quality of the copying personnel, and change from the ideological level, which can achieve the purpose of reducing the management line loss.
1.2 According to the characteristics of loss
1.2.1 Variable loss
The so-called variable loss refers to the loss which varies with the load current in the power grid according to its size, including the loss in the wire, the copper loss in the transformer winding, the loss in the ammeter and the current coil of the watt-hour meter.
1.2.2 fixed loss
The so-called fixed loss refers to a loss that is independent of the load current in the power grid and does not change with it. These include the iron loss of the transformer, the dielectric loss of the capacitor, the losses in the voltmeter and the voltage coil of the watt-hour meter.
1.2.3 unknown loss
The so-called unknown loss refers to a loss of the difference between the actual line loss and the theoretical line loss. The loss is variable and the quantity is unknown. It is difficult to determine by instrument and calculation method. It can only be determined by the month-end electricity statistics, including the loss of electricity and electricity by users, leakage loss, meter reading and errors in electricity bills. Loss, loss caused by meter error, etc.
2 damage of distribution network line loss
2.1 fever is the most prominent problem caused by line loss
The process of heating is the process of converting electrical energy into heat energy, causing the loss of electrical energy; heating causes the temperature of the conductor to rise, prompting the aging of the insulating material, shortening the life, reducing the degree of insulation, causing thermal breakdown, causing accidents in the distribution system, for example The insulation life of the transformer at 140 ° C will be 128 times lower than the normal operating temperature (98 ° C). Especially when the capacity of distribution lines in a building is insufficient, heat is often the direct cause of electrical fires.
The influence of heat on the contact part is most obvious, and quite a lot of faults in the distribution network are caused by the resistance heat at the contact point. The contact resistance at the general contact is often greater than the resistance of the material at both ends. Even under normal load current, severe heat is generated, which in turn increases the contact resistance of the conductor, causing a vicious cycle, eventually causing the contact portion to burn out and causing a malfunction. The crimping of overhead lines and the intermediate joints of power cables are often the most common points of accidents.
2.2 The line loss of the electrical system causes a large amount of energy waste
The line loss of the power distribution system is not wasted into useful energy and was wasted, and the heat is also dissipated by means of ventilation, cooling, etc., and electrical energy is also required. According to the statistical data, the line loss rate of the general distribution network is above 3%, and in severe cases it can reach 10% or even higher. This not only means the loss of electrical energy, but also the massive waste of primary energy and more pollution to the environment. Therefore, the economic loss caused by the line loss of the distribution system is reflected in all aspects of the transmission, supply and use of electricity. If measures are not taken to reduce the line loss rate of the distribution system, it will inevitably have a negative impact on the national energy utilization, environmental protection and economic benefits of the enterprise, and as the demand for electricity continues to increase, the power loss will become larger and larger. Each unit of electricity must start from the overall situation, and reduce the line loss technically and administratively.
3. Analysis of measures to reduce energy loss in power distribution system
3.1 Management measures for loss reduction and energy saving of power distribution system
3.1.1 Instruction Management
The electricity management department should carry out the theoretical calculation of the line loss and compare it with the actual situation to obtain a more reasonable line loss indicator. The indicator will be released to the grassroots departments in the annual, quarterly and monthly months and included in the economic responsibility system. In addition, the user's meter reading rate, voltage pass rate, permittivity availability rate, capacitor input rate and energy-saving activities should be assessed for small line loss indicators, and rewards and penalties should be clearly defined to mobilize employee management enthusiasm.
3.1.2 reactive power management
In addition to the normal power factor assessment, for some users only care about whether the power factor is greater than 0.9, do not pay attention to the situation of reactive reversal, selectively install two-way in the user with large power consumption and power factor close to 1. Reactive energy meter; according to the characteristics of load power, choose the appropriate capacitor switching basis.
3.1.3 Harmonic management
With the increase of non-linear power load in the power grid, such as rectifier equipment, electric melting equipment, electric locomotives, energy-saving appliances, fluorescent lamps, televisions, computers, etc., harmonic pollution in distribution systems is becoming increasingly serious. Harmonics not only reduce the power factor of the system, but also generate thermal effects in equipment and lines, resulting in power loss. Therefore, the electricity management department should detect the presence of harmonics and the degree of pollution of the system, so that there are counts and harmonic suppression measures should be taken when necessary.
3.1.4 Measurement Management
Correct electric energy metering is not only the basis for reducing line loss, but also the basis for assessing technical and economic indicators. The meter should be regularly checked and verified, and the magnification should be adjusted in time to reduce the comprehensive error of the energy metering device. For the energy meter of the key parts, the advanced all-electricity meter should be used as much as possible, and the collection system should be promoted as much as possible.
3.1.5 Statistical analysis
Line loss statistics are performed by partitioning, sharding, and voltage division. The current situation of line loss is analyzed regularly, and problems in voltage and reactive work are analyzed. Improvement measures are proposed to ensure the completion of line loss indicators. Do a good job of monthly and annual line loss rate curves, master the system active, reactive power flow, power factor, voltage and line loss, etc., to provide basis for meeting next year's load growth, improving power quality, system economic operation and developing damage reduction measures.
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