Reduce Electricity Costs with Dynamic Load Management

For industrial companies with an annual electricity requirement of over 100,000 kilowatt hours (kWh), the electricity price is made up of three components: the base price, the unit price and the demand price. The latter two together make up the grid fee. This has increased by an average of around 6.5 % per year over the last ten years, and therefore significantly more than inflation. The main reason for this is the investments that grid operators need to make in the energy transition and grid expansion. Neither of these has been finalised yet, so it is likely that grid fees will continue to rise. At the same time, electricity consumption has increased in many companies in the food industry. This is because, in the course of decarbonisation, processing is increasingly being electrified.

However, companies can actively influence the demand charge costs. This is because these are determined on the basis of the highest 15-minute average load within the billing period – usually one year. This means: The lower this average load, the lower the demand price. However, if the average load over a quarter of an hour is only above the previous maximum once, a load peak occurs and the demand charge costs for the entire billing period increase.
A sample calculation makes this clear: Assuming a demand price of € 200/kWh, a peak load that is 100 kW higher than the previous value will result in additional costs of € 20,000 per year.

A load peak occurs when there is a high demand for power, for example when a large number of machines and systems are switched on at the same time. In addition to the usual load from machines and systems, electrification means that other consumers, such as a heat pump or a company charging infrastructure for electric vehicles, are increasingly being added. For example, a typical combination of two single and two double wall boxes and a fast-charging station can reach a load of up to 250 kW. When employees arrive at work at the start of production and connect their vehicles to the charging points, and then start up the machines and devices in production, the 250 kW of the charging infrastructure is added to the existing load. The demand price increases by € 50,000 per year. In addition, a peak load can overload the connection and cause grid instability, which can have a negative impact on the machines and systems concerned.

To avoid this, master charging stations are usually equipped with load management. This limits the power of the charging points connected to the master to a pre-set value. This power is distributed across all the charging points in use. However, this does not always prevent a peak load, because the company's other energy-related circumstances – such as what other consumers are running at the time or how much of the company's own electricity can be used – are not taken into account. Another disadvantage of this solution is that the installed capacity of the charging infrastructure can never be fully utilised. It is always limited to the set maximum value.

In contrast to this static load management, dynamic load management includes all relevant energy consumers, generation and storage systems and can take individual circumstances and requirements into account. Due to rising grid fees, a system like this is increasingly worthwhile for smaller companies as well, and usually pays for itself within one to two years. The technical basis for dynamic load management is a load controller like the econ peak from econ solutions. It monitors the existing electricity meters, machines and devices, charging points, energy storage systems and PV inverters. It then uses the data collected to dynamically control them according to the current consumption situation, either of the entire property, the building or part of the building. This means that it also reliably prevents smaller load peaks and the charging points can deliver their full power, provided that no load peak occurs as a result.

Two scenarios illustrate this: While pumps, compressors, heating and cooling systems are running at the plant and some electric vehicles are being charged, the PV system is only supplying a small amount of electricity due to heavy cloud cover. The controller then temporarily reduces the power to the consumers that are not urgently needed at that particular time, or switches them off completely. The company can configure which ones are eligible for this individually and in detail; prioritisation is also possible. This load shedding control is based on the predictive calculation of the load development for the current 15-minute period. This avoids peak loads without the risk of severely limiting the availability of required machines or electric vehicles and impairing processes.
On a sunny day when there is no production, on the other hand, the econ peak reduces the output of the PV system so as not to exceed the grid feed-back capacity of the house connection and to avoid penalty payments to the grid operator due to excessive feed-in quantities. For example, if the company has an ice storage system, the controller switches it on to temporarily store the energy that is not currently needed. The power of the PV system is then reduced accordingly later.

In reality, the electrical and structural conditions are very different, as are the requirements and objectives of the companies. For example, in a medium-sized company, devices should not be controlled directly by the controller. Instead, a traffic light circuit should indicate to employees when a device should be turned down or switched off. econ solutions has programmed the controller here so that it does not switch devices itself, but sends the control signals to a PLC (programmable logic controller), which performs the corresponding traffic light switching.
Shutdowns can also be carried out on the basis of complex timers or logics, e.g. linked to certain temperatures. The duration and extent of the power reduction can also be defined separately for each device and system. Different electricity tariffs can also be taken into account.
With dynamic load management, companies in the food industry can avoid peak loads, enabling them to keep their electricity costs as low as possible. At the same time, operational reliability is guaranteed and it is ensured that the electric vehicles of the management and the delivery department are prioritised for charging.