What should be the penetration percentage of non-Manageable energies in an electrical system?

In a very simple way we will try to respond to a topic that we can consider somewhat complex.

Introduction

The first thing that we must understand is that, in electric systems, demand and the generation must be in total harmony and balance, electric systems cannot exceed or lack power or capacity, which is equivalent to say that: electrical systems must be capable of raising or lowering their capacity as demand increases and decreases. The capacity of electrical systems to follow the changes in the demand is known as system regulation capacity.

The power that is demanded must be supplied instantaneously, when we turn on a light bulb or an electric furnace with a great metallurgy, the electrical systems, must act instantaneously to increase or reduce their capacity and absorb the changes in the capacity demand.

The ability of some generators to quickly increase or decrease their power when the demand increases or decreases is known as generator regulation capacity, that’s how we can say that certain types of technologies such as the hydraulic or the open-cycle power plants have good regulatory capacity, while the coal steam thermal power plants have little regulatory capacity, there are also generation plants that are built in a special ways as control centers, with characteristics that allow them to increase or reduce a large proportion of their capacity in a very short time.

On the other hand, non-Manageable energies are does that, depending in a natural resource that cannot be controlled by men, such as the wind or the sun, cannot raise or lower their capacity when desired, on the contrary, they suffer sudden increases and decreases of their power, which is also the contrary of the main objective, that is, maintaining the balance between the generation capacity and the demand.

In electrical systems exists what is called the generation inertia, which is contained in the masses of the rotors of the rotating generators, this inertia, during small instants, allows to absorb little desviations between the generation capacity and the demand capacity.

In this sense, the larger, robust and interconnected the electrical systems are, the more inertia and better response they will have, and the smaller or isolated, the worse their response to changes will be.

Based on the above, electrical system can install technological equipment or action systems to agilely maintain the equality between the generation and the demand. As regulation equipment that can bbe installed in regulation centers and battery banks.

Also the electrical systems can be operated in such a way that the online generators have sufficient reserves to attend the demand’s increase, also they can count on generation reserves that can quickly enter online if they are required by the demand and the distribution companies or big customers can participate in load shedding programs, which means that certain loads such as companies and industries, agree to be disconnected if there are any sudden increases in the demand that cannot be quickly supplied by generation systems.

As it can be understood, both in the decision making for the installation of regulation technologies and in the operation with generation for regulation, the economic factor must be taken into account, to maintain a great quality of energy or to count with a good regulation system, it is necessary to make investments.

Answer

In general sense, we can say that the regulation capacity of an electrical system, apart from the natural regulation associated with the type of technology of the interconnected electrical system, will also depend in great measure on: the quality of the energy that the interconnected electrical system aspires and the investments in technologies or operations carried out to keep the generation and the demand united.

When we talk about the percentage of penetration of the non-manageable renewable energy, we are about a capacity that is assigned or stablished based on the characteristics of an electrical system, and the investments that can be realized in equipment and reserves of operation, to maintain an electrical system working within the previously stablished quality parameters.

Thus, an electrical system that according to certain quality parameters and previously stablished operation has the capacity to maintain the harmony between the generation and the demand when it counts with the injections of a 15% of the capacity of non-Manageable energy, we say that the non-Manageable penetration capacity of the system 15%.

However, if in said electrical system the criteria or quality parameters are modified, or the criteria or the operation parameters of both generation and demand are modified, or greater investment is made in regulation equipment, such as the use of batteries, the percentage of penetration of non-Manageable energy could be impacted very significantly.

For the Dominican Republic to carry a real study that stablishes the percentage of penetration of non-manageable energies, it must previously define the quality of the energy that it aspires in its electrical system, and must determine the investments in technology equipment and operation that it is willing to carry out.

When we talk about penetration percentage in the Dominican Republic, it refers to the penetration percentage under the current conditions of the electrical system, without considering the increase in the demand, without improving the poor quality of the energy we have, without making any kind of investment in technological equipment and without the generation reserves.

In the previous conditions the experts in operation of our electrical system have mentioned, in an empiric and unofficial way, that the penetration percentage for the Dominican Republic is of the order of 20%, which means that instantaneously, the percentage of non-Manageable energy cannot surpass the 20% of the instantaneous demand of the electrical system, in a more practical way we can say that: if the instantaneous demand of power of the Dominican Republic is, in hours of low demand, 1,500 MW, and in peak time 2,500, the capacity delivered instantaneously by the of group of non-manageable plants should be between 300 and 500 MW.

Now, if we consider the plant’s factor of the photovoltaic and wind power central existing in our country, which is of the order of 40%, we would have that the non-manageable energy capacity that can be installed in our country is of the order of 750 to the 1,200 MW.

If the country, taking care of the international commitments and what is established in the regulations, decides to make investments to improve the regulatory capacity so that in our electrical system can manage more non-Manageable energies, we could talk about the 25% or the 30% of regulation capacity, in this case we would be talking about: to 25% of regulation between 938-1563 MW installed, for 30% between 1,112 - 1875 MW installed.

From that we can deduce that the regulation or penetration capacity is not a fixed percentage, it can be adjusted at will and depending of multiple factors, such as: the characteristic of electrical systems, generation technology, capacity of load shedding, the regulation equipment used and the way of operating the electrical systems, therefore, for each country it is necessary to establish the quality of energy that it wants to achieve and the amount of investment that it can make and these factors will be what will determine the capacity for regulation or penetration of non-Manageable renewable energies that said electrical system can support.

In a simple and understandable way I have tried to explain the topic of penetration, for any other clarifications, I am at your orders.

Other important questions that arise in relation to this topic are the following:

Who should pay for investments to improve the regulatory capacity of the system or the penetration rate of renewable energies?

With which objectives has the Dominican Republic used the topic of penetration percentage, to take care of the quality of its electrical system, not to make investments in regulation or to stop non-manageable renewable energies?

To find the answers to these important questions or to know other related topics, please visit our website:
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Francisco Ortega, IEC Manager, April 2019

La producción energética de la República Dominicana aumentará entre un 30 y un 35% solo con la producción de Punta Catalina, reveló el presidente Danilo Medina.