Power system maximum hours for the year. The concept of power system load schedules and electricity tariffs. Krasnodar Territory hurries to the rescue
3.3. Power system balance
The balance provides for the correspondence (equality) between the incoming and outgoing parts. The power balance is built separately for active and reactive power.
The active power balance of a power grid at time t can be represented as follows:
where i - serial number power plants; j - serial number of the power grid transmitting active power to the considered one; i is the serial number of the power grid receiving active power from the considered one.
The incoming part of the active power balance includes the total available active power of power plants
the same amount of active power received from other
energy networks
The expenditure part of the active power balance consists of the maximum active load of the given
Loss in electrical networks
power grid Nmax(t), active power consumption for auxiliary needs, the amount of active reserve power and active power supplied toother power supply networks,
A similar expression can be written for the reactive power balance:
3.3.1. Expenditure part of the balance
To draw up a power balance, graphs of electrical loads are used, which display the change in power consumption during the period under consideration. Load graphs can express the power consumption mode of individual enterprises, sub-sectors, districts, district and interconnected power systems. The modes of operation of power plants depend on the modes of electricity consumption: the main equipment of power plants, power lines and transformer substations. Power consumption modes can be presented in the form of tables or graphs. Electrical load curves are considered for both resistive and reactive loads. The discrepancy between the configurations of these graphs is determined by the differences in the modes of consumption of active and reactive power by individual types of consumers.
Depending on the duration of the period under consideration, there are:
daily, weekly, monthly and annual load schedules;
winter, spring, summer and autumn.
When planning loads, use standard (averaged) schedules. They are compiled for different groups of consumers (industrial, agricultural, municipal) and for specified periods of time. In a typical graph, each load ordinate is the arithmetic mean for the period under consideration.
Load curves are characterized by: configuration; maximum, average and minimum loads; ratios of these loads.
Typical graphs of power system loads for a day, week, month, year are shown in Fig. 3.1.
Figure: 3.1. Daily load schedule
Indicators of the daily schedulepower system loads.To analyze the participation of generating capacities in covering the daily load schedule of the power system, three parts are distinguished in it: peak, half-peak and basic.
Figure: 3.2. Components of the daily load schedule:
I, II, III - peak, half-peak, baseline
The daily schedule of the electrical load of the power system is characterized by a minimum RTT,average R wed , maximum
The following ratios are considered: filling factor of the daily schedule
where E day - daily energy consumption, million kWh / day; E p - potential energy consumption; average load
P av \u003d E day / 24
minimum load factor
α min \u003d Pmin / Pmax.
Indicators (β day and α min reflect the power consumption mode and make it possible to compare and analyze graphs of different scales.
An increase in the share of housing and communal and agricultural loads, and a reduction in night shifts lead to a loosening of schedules. An increase in the proportion of continuous production, an improvement in equipment utilization - to tighten schedules. The values \u200b\u200bof the indicators on the graph depend on the structure of the industry, climate and other factors. So, for different associations, α min and β days (for December 1991) had the values \u200b\u200bpresented in Table. 3.1.
Creation of interconnected energy systems, the use of two-rate tariffs for electricity consumption, the commissioning of consumers-regulators (for example, the operation of a pumped storage power plant in pumping mode), an increase in the shift factor of enterprises, artificial displacement
Table 3.1
Regional indicators of the power consumption mode for the month
|
Union | ||
|
Northwest Center South |
0,84 0,86 0,89 |
The weekly graph of electrical loads displays the fluctuation of the load over the days of the week, mainly due to weekends and holidays. In addition to load fluctuations within individual weeks, there is
there are fluctuations between weeks caused by changes in the duration of daylight hours of the day, an increase in load. Within each month, the weekly electricity consumption is not the same:
Figure: 3.5. Annual load curves
Figure: 3.6. Changing the fill factor values \u200b\u200bof the daily schedule
The weekly power consumption graph is shown in Fig. 3.3. Monthly graphs of the electrical load of the power system (Fig. 3.4) display the fluctuation of the average weekly load by weeks of the month. Annual graphs of electrical load show fluctuations in average monthly R srmmes or average monthly regular highs -Pavmes, regular highest monthly highs P maxi , absolute monthly highs R" tah by months of the year (Fig. 3.5).
The main indicators of the annual schedule are:
Figure: 3.3. Weekly electricity consumption schedule
Figure: 3.4. Monthly load curves
annual schedule fill factor
where R max month i is the maximum load of the power system for each month; R max year i - annual maximum load of the power system; R max average year - average annual maximum load;
growth rate,characterizing an increase in the maximum load of the year under consideration in comparison with the previous one,
where R tyax1 i , R tah i 2 - maximum monthly loads in January and December of the year in question.
If Cr \u003d1, then the annual load schedule of the power system is called static,if Cr >1 - dynamic,reflecting the intra-annual increase in the load;
annual hoursusing the maximum load of the power system
where E gds is the amount of energy consumed by the energy system per year; P max c - maximum system load.
Indicator A c characterizes the estimated number of hours at which the annual demand for electricity is covered under constant load. It can be defined as the product of the number of hours in a year and the filling factors of the daily, weekly, monthly and annual load graphs (Figure 3.6), h:
where β weeks and β months - filling factors of the weekly and monthly load schedules, respectively.
If the value is known h c , found using the coefficients of unevenness of the load curves, then the annual maximum of the electrical load of the power system can be determined in the following form:
Calculation and construction of combined electrical graphspower system loads.There are several methods for constructing daily power system load graphs. For graphs for the next period, with a slight change in the structure of electricity consumption, the analogy method is used, in which the reporting schedule with the necessary clarifications is taken as the basis. For the construction of graphs of a more distant perspective, as well as for new rapidly developing power systems, the following are used: integral, synthesized methods and the method of generalized characteristics, which are most widely used.
The method of generalized characteristics, developed at the institutes "Energosetproekt" and ENIN them. G.M. Krzhizhanovsky, uses the characteristics to determine the number of hours of use of the maximum load of the power system, depending on the location, the specific weight of household power consumption and the number of hours of use of the maximum industrial and transport load of power supply. This makes it possible to determine the value of the maximum load of the power system for a typical winter and summer day. According to the typical load curves of the power grid and the daily load indicators, the power system load schedule is calculated for winter and summer days.
The annual schedule of monthly maximum loads can be expressed by the following equation, MW:
where a l is the ratio between the summer and winter maximums of the electrical load; / - ordinal number of the month; P" max 12 - daily maximum load in December of the year preceding the considered one.
As a rule, σ month \u003d 0.96 ... 0.97; β days varies by months and can be determined when constructing an auxiliary graph
In addition to this graph for the balance of energy and fuel of the system, an annual graph of average monthly loads is built. For its construction, annual charts of maximum monthly loads and coefficients of daily and monthly unevenness are used:
1cm. fig. 3.6), applying (β days l, β days . 3 for a specific number of hours using the maximum of a system located in a specific geographic area. Failure of the annual schedule of maximum monthly loads (mainly in the spring-summer period) is used for capital repairs of equipment.
The coincidence in time of production and consumption of electricity, and, consequently, the impossibility of "working at the warehouse" determine the need to create reserves of power in the energy systems in operation. The main task of redundancy in the power industry is to ensure maximum reliability and uninterrupted power supply, as well as the stability of the quality parameters of energy both in the event of an emergency failure of the units, and during scheduled capital and current types of equipment repair. Violation of power supply leads to economic damage to both consumers and the power system itself. The presence of a system-wide power reserve, which is maneuvered by the dispatching service of the power system, and the creation of large power interconnections, significantly increases the reliability of power supply to consumers.
Required power reserve of the power system N p consists of the following types of reserves: load N p. load, emergency - N equal\u003e repair N prem, national N r.nkh , those.
The load reserve is necessary to maintain the specified frequency level in the system in case of irregular deviations (fluctuations) of the load. The amount of the reserve depends on the scale and characteristics of consumers and fluctuates within the following limits: 4 ... 5% for power systems with a maximum load of 3 ... 5 million kW; 1 ... 1.5% for systems with a load exceeding 25 ... 30 million kW. The load reserve must be constantly ready for use and is located on the units operating with some underload from large power plants with highly mobile equipment, primarily hydroelectric power plants).
The approximate value of the load reserve is calculated using the following formula:
where P max p - regular (calculated) maximum load (mathematical expectation of the weighted average maximum load of the power system on normal working days, which are considered Tuesday-kick, Wednesday, Thursday and Friday), MW.
The emergency reserve compensates for the decrease in power caused by emergency equipment downtime due to its damage and is intended for the quick commissioning of generating capacities in mutual
Total installed capacity of the power system
Maximum operating power of the power plant;
Power reserve;
Duplicate power of electric
me out of order as a result of accidents at the station and in power lines. The value of the emergency reserve should be taken on the basis of the total capacity of the entire power system, the number of units installed at power plants and should not be less than the capacity of the largest unit in the system.A repair reserve is necessary in the power system to carry out scheduled preventive repairs (capital and current) of the main equipment of power plants without disconnecting consumers and reducing the reliability of power supply.
The national economic reserve presupposes the provision of energy for prematurely commissioned new facilities or the excess energy demand of existing enterprises. The value of this reserve power is taken equal to 1 ... 2% of the expected maximum load of the power grid.
On Tuesday, August 8, the Ministry of Energy reported that electricity consumption in Crimea due to the heat wave broke the record set in 2012. This was due to the active use of air conditioners during the peak holiday season. In order to cope with energy shortages during peak consumption hours, it was previously decided to introduce temporary power outage (TPS) schedules.
In particular, on the evening of August 7, after the introduction of the GWO, more than 108,000 people in Crimea and Sevastopol were left without electricity for about 2 hours.
Krasnodar Territory hurries to the rescue
In a number of districts of the Krasnodar Territory, on the recommendations of the Ministry of Energy, power outages will be carried out, Gazeta.ru reported on Wednesday, August 9, citing the press service of the regional administration. As stated in the message, which has already been removed from the administration's website, the power supply will be turned off "to stabilize power flows, prevent damage to equipment and disrupt the stability of the parallel operation of the Crimean Peninsula energy system with the Unified Energy System of Russia, accompanied by the satisfaction of the needs of a significant part of consumers of the Republic of Crimea."
Power consumption restrictions were to be made in the amount of up to 110 MW in the period from 20:00 to 23:00. They should have been left without electricity in Novorossiysk, Anapa and Gelendzhik, as well as in the Crimean, Abinsk, Slavyansk, Krasnoarmeisk and Temryuk districts of the Krasnodar Territory.
The Ministry of Energy denied that the department had given recommendations on the introduction of GWO in the Krasnodar Territory.
They also explained that the schedule of rolling blackouts during peak hours was introduced only on the territory of the Republic of Crimea. “In connection with the current situation on the territory of the Republic of Crimea, a schedule of rolling blackouts was introduced during peak hours. At the same time, the Ministry of Energy of Russia did not give recommendations on the introduction of a schedule for temporary blackouts in the Krasnodar Territory. The information published on the administration's website is erroneous and will be removed from the website in the near future, ”RNS quotes from the statement of the Ministry of Energy.
Meeting
Russian Energy Minister Alexander Novak held a meeting in Yalta on power supply to consumers in the Krasnodar Territory and the Republic of Crimea. According to the minister, a record for power consumption was broken for several days in a row in the regions.
Alexander Novak
Minister of Energy of the Russian Federation
On August 7, the consumption of electric power in Crimea exceeded the historical maximum of loads and amounted to 1,249 MW, which reached 70 MW the summer maximum. And in the Kuban energy system, the historical maximum was 5,032 MW, which is 433 MW higher than the maximum recorded in July 2016.
Among the main reasons for the current situation, the head of the Ministry of Energy named the growth of electricity consumption by industrial enterprises, the development of the resort and recreational complex of the regions and an increase in household load due to the use of air conditioners due to abnormally high temperatures. The consequence of this was a sharp change in the structure of consumption of active and reactive power in power systems.
SO UESThe meeting noted the fact that out of 284 diesel generator sets (DGS) with a total capacity of at least 109.6 MW (122 MW including Sevastopol), provided for by the regulations for the transfer of consumers to decentralized power supply to cover the arising power shortage, only 75 DGS were included with a total capacity of 18.3 MW.
Alexander Novak ordered to carry out extraordinary bypasses of power lines, to notify the population about the possible use of GVO and explain the need for measures to be taken, and also temporarily banned unscheduled and planned repair work of the backbone network and any work at power plants with a higher voltage class of 110 kV and above. In addition, an order was given to the Council of Ministers of the Republic of Crimea, as soon as possible, to bring all diesel generators, necessary to cover the power deficit, into operable condition.
Peak of technical capabilities
According to the System Operator, the abnormal heat (with an increase in the average air temperature by almost 10 ° C above the norm for this time of year) led to the fact that the IES of the South exhausted technical capabilities to ensure the current level of electricity consumption in the Crimea and the Kuban. By 18:00 on August 7, the value of the power flow through the power bridge reached its maximum values \u200b\u200b- about 800 MW, while solar power plants, which provide part of the consumption in the Crimean energy system, reduced their power to zero in the evening.
SO UES In addition to new historical highs in the power systems of Crimea and Kuban (in the latter, record values \u200b\u200bof power consumption for the entire period of its existence are recorded for three days in a row), consumption in the Stavropol Territory and in the Astrakhan Region beats records for the maximum power. It is logical that the IES of the South as a whole took a new record for power consumption. During the daytime maximum load on August 8, the power consumption in this IES reached 15,754 MW, which is 6% (907 MW) higher than the maximum recorded on July 18, 2016.
An increase in electricity and power consumption and a change in the ratio of consumed active and reactive power due to the specific structure of consumption caused by hot weather led to a decrease in bandwidth electrical connections and the depletion of reserves of active and reactive power in the power systems of the IES of the South, was recognized in CO. The only way to ensure the stable operation of the power system is to enter the GVO, which will avoid prolonged equipment failure, overloading of power lines and network equipment and reducing the voltage in the network below the minimum permissible values, the operator also said.
SO UES According to Kommersant, all “systemically important” capacities are included. Inter RAO clarified that the Dzhubginskaya and Sochinskaya TPPs were loaded, and OGK-2 said that the CO gave the command to turn on 1.6 GW (i.e. 6 out of 8 blocks) at Novocherkasskaya GRES, 2.1 GW (7 of 8 units) at the Stavropolskaya TPP and 250 MW (both units) at the Adler TPP. There are 3 units in operation at Rostov NPP (about 3 GW). Rosseti explained that “the most reliable power supply schemes have been created in the networks of the Kuban,” when the CO decides to launch the GVO, the company “will carry out the appropriate command”.
Lack of capacity
For stable work energy systems in Crimea will additionally supply 4 mobile gas turbine power plants (MGTS) with a capacity of 22 MW each, said Mikhail Sheremet, a member of the State Duma Committee on Energy, former First Deputy Prime Minister of the Crimean Government. According to him, MGTS will be used until the commissioning of two CHPPs under construction.
Mikhail Sheremet
deputy, member of the RF State Duma Committee on Energy
It was decided to create a powerful energy fist so that the power shortage that we are experiencing due to the abnormal heat can be painlessly overcome. We have a huge number of ARIPs [autonomous backup power supplies - DSP], from which a small cluster is formed, which together will give us another 80-90 MW, which will cover the power shortage. Moreover, 4 more MGTS are being transferred, which will solve pressing problems. Their capacity is standard, 22 MW each.
However, the problem lies not only in the lack of generation, but also in the Taman energy system as a whole. The South-West region of the Kuban energy system is traditionally included in the list of problem points of the UES of Russia. The Ministry of Energy and SO admit from year to year that failures are possible here. The situation also worsened after the annexation of Crimea: it was required to create from scratch the power supply system of the peninsula from the Russian side, but so far only the Kerch energy bridge has been laid.
As reported to RIA Novosti in the press service of SO, the organization considers it very important to comply with the terms of commissioning the 500 kV power transmission line "Rostovskaya - Taman", which will significantly increase the reliability of power supply in the region, and the announcement of a tender and the construction of a power plant in Taman. The need to build a power plant in the south-west of the Krasnodar Territory in SB was talked about for a long time, even before the Crimea became part of Russia, warning about the threat of a power failure.
However, the 940 MW plant still does not have an investor (the tender was declared invalid), and the overhead lines should be completed only by the end of the year. At the same time, as Kommersant previously wrote, the commissioning of networks for projects on Taman (railway approaches to the Kerch bridge and the port) are constantly shifting, and the supply scheme is changing. It is planned that the Ministry of Energy may announce a tender for the construction of a power plant this summer.
Work to stabilize the situation is underway not only in the Krasnodar Territory, but also in Crimea itself: according to RIA Novosti, an additional 20 MW of capacity will be commissioned on the peninsula by September, and about 150 MW by the end of the year.
According to forecasters, extremely high temperatures in the region will remain until the end of the week.
According to the form of load graphs, five groups of industrial load, household consumption, electric transport, street lighting, and agricultural needs are distinguished. The industrial load due to one- and two-shift enterprises is reduced at night and in the evening.
Household consumption increases significantly in the morning and evening, the evening peak is longer. Transportation peaks in the morning and evening hours. Street lighting has a maximum at night. Agricultural consumption schedules are fairly uniform with seasonal changes in its value.
The total load graph is obtained by adding up the hourly loads of all consumers for typical winter and typical summer months
Fig. 1 The total load graph on a winter day.
Fig. 2 Summarized load graph on a summer day.
The winter schedule has 2 peaks (Fig. 1), the summer one - 3 (Fig. 2), which is explained by the longer daylight hours (the lighting is turned on after the end of work at one-shift enterprises and a decrease in transport traffic).
Summer loads are lower in absolute value.
To determine the annual demand for electricity, the annual schedule of the duration of the loads is used (Fig. 3)
Fig. 3 Annual schedule of load duration and annual schedule of monthly maximums (Fig. 4).
Fig.4 Annual chart of monthly highs.
The duration of the load is determined by summing it up for 210 winter days and 155 summer days. The area under the annual load duration curve determines the total annual electricity demand.
2. Methods for covering electrical load peaks
Due to the significant unevenness of the electrical load during the day, an important task is the rational coverage of relatively short-term, but significant load peaks. According to the number of hours of use of the maximum load, basic, semi-peak and peak units are distinguished. For basic power plants, the use of the maximum load per year is 6000 - 7500 h, for semi-peak and peak - respectively 2000 - 6000 and 500 - 2000 h.
Since the existing IES and CHP plants are not able to fully cover the variable electric load schedule, special half-peak and peak units should be developed and put into operation.
When designing, basic power plants are required, first of all, to have high thermal efficiency, which determines increased capital investments.
For TPPs operating relatively few hours per year (peak and half-peak), the main requirement is high maneuverability and low capital investment, although sometimes this is achieved at the expense of thermal efficiency.
Consider the main ways to cover electrical load peaks
1. The use of hydroelectric power plants due to the simplicity of starting, stopping and changing the load is the best way
2. Using the power reserve of conventional steam turbine power units operating in the mode of frequent starts and stops.
3 Application of highly maneuverable units, such as peak and semi-peak steam turbine, gas turbine and combined cycle pumped storage power plants. Pumped storage power plants during the period of minimum electrical loads pump water from the lower reservoir to the upper one, consuming energy from the network, and during the period of maximum loads they work as a hydroelectric power station
4. The use of temporary overloading of steam turbine TPPs due to regime measures (changing the parameters of the steam in front of the turbine, shutting down the HPP, etc.)
5. Energy storage by filling gas storage facilities for compressed air, which is then used in gas turbine installations, heat storage in the form of hot water and electricity in electric batteries
To facilitate the passage of electrical load peaks, load curve equalization can be used, which is understood as an active influence on the consumption mode, leading to a decrease in load peaks. These goals are achieved by increasing the shift in the work of enterprises with the use of incentive night tariffs for electricity, the creation of interconnected power systems due to the different times of the maximum load in areas with different geographical longitudes, the presence of consumers of regulators, the hours of which the power system determines.
Fig 5. The annual schedule of the duration of the household load.
Of great importance for determining the operating modes of CHP and boiler houses in the design of heat supply systems is the annual schedule, but the duration of the utility load (Figure 5). It shows the change in the heating load, which includes heat for heating and hot water supply, from its maximum value to the minimum value throughout the year.
To build an annual schedule, it is necessary to know the duration of the standing of various outdoor air temperatures during the heating season for a given climatic zone where a CHP or boiler house is being built, to determine the hourly heat consumption for heating, ventilation and hot water supply, depending on the outside air temperature, build a network temperature graph (Fig. 6 ) according to the temperature, schedule and duration of each flow, build an annual schedule of heat supply.
Figure 6 Network temperature graph.
In order to stimulate the rational use of fuel and energy resources, seasonal prices for natural gas and seasonal tariffs for electric and thermal energy, differentiated by time of day and days of the week, tariffs for these types of energy, as well as other forms of incentives are established in the manner determined by the government of the Republic of Belarus ...
An important moment of economic incentives for energy saving is the transition from one-rate tariffs to two-rate and zone tariffs, allowing to smooth the national load curve. This leads to increased energy efficiency at the stage of electricity and heat production. The graph (Fig. 7) clearly shows that it is extremely beneficial for the consumer to reduce the load during the hours when the tariff in the power system is maximum.
Fig. 7 Daily electricity consumption (curve 1) and tariff differentiated by time of day (curve 2) for an electrometallurgical plant in Germany
Electricity (power) tariffs are price rate systems used for payments for electric energy (power).
Two-part tariff is a tariff for industrial and similar consumers, which provides for a basic payment (for the contractual or actual value of the largest half-hour combined active power consumed during the hours of maximum load of the power system) and an additional payment (for the actual amount of consumed active energy) for the billing period.
The basic payment of the two-rate tariff is the price of 1 kW of the contractual or actual value of the highest consumed active power, adopted in accordance with the declaration on the level of tariffs for electricity supplied by the Republican unitary enterprises of the electric power industry of the Belenergo concern.
Additional payment of two-part tariff - the price of 1 kWh of consumed active energy, accepted in accordance with the declaration.
